Accident and Serious Incident Reports: AW
Accident and Serious Incident Reports: AW
Definition
A selection of reports relating to accidents and serious incidents which involved Airworthiness as a factor.
The reports are listed below in two groups, the first of which lists the event according to the system affected. The second group identifies events in which Airworthiness was a contributing factor and lists the events by category.
Group 1 - Systems
Airframe
On 4 October 2023, an Airbus A321 climbing out of London Stansted with the eighteen occupants all seated towards the front of the passenger cabin was discovered to have several missing or damaged windowpanes on the left side towards the rear. The aircraft returned to land where damage was also found to one of the horizontal stabilisers. The window panes fell out because of damage by infrared energy emitted from high-intensity lights during a filming event the previous day. Four previous similar events were identified but it was found that knowledge of them was not widespread in the aviation community.
On 5 January 2024, a Boeing 737-9 which had just departed Portland was climbing through 14,800 feet when there was a loud bang followed by a rapid decompression. The cause - the loss of a fuselage plug fitted at an unused door location - was immediately obvious. An emergency was declared and a landing back at Portland was made after a total of twenty minutes airborne. The Investigation is continuing but has found that the fuselage plug involved was installed without being properly secured and noted that the aircraft had only recently been delivered new to the operator.
On 8 July 2019, a loud bang was heard following intermediate flap selection on a Boeing 747-400F making an approach to Harare and a concurrent uncommanded right roll was countered with left aileron. The flight was completed without further event but a post-flight inspection found part of the inboard section of the right wing flap assembly was missing and the right fuselage impact-damaged in several places. The missing flap section measuring 3.7 metres by 0.6 metres was recovered with detachment attributed to undetected fatigue cracking already present at component installation. A long history of problems with 747 flaps was noted.
On 23 February 2020, a Bombardier Challenger 605 making a flapless landing after a system failure during descent briefly lost control when reverse thrust selection after a normal touchdown was followed by the aircraft becoming airborne before stick push activation was followed by a hard second touchdown. Structural and abrasion fuselage damage was caused. The Investigation attributed the flap failure to corrosion within the specified maintenance inspection interval and the brief loss of control during landing to a combination of inadequate crew preparation for the landing and the fact that simulator replication of aircraft handling did not correspond to reality.
On 1 April 2011, a Southwest Boeing 737-300 climbing through FL340 experienced a sudden loss of pressurisation as a section of fuselage crown skin ruptured. A successful emergency descent was made with a diversion to Yuma, where the aircraft landed half an hour later. Investigation found that the cause of the failure was an undetected manufacturing fault in the 15 year-old aircraft. One member of the cabin crew and an off duty staff member who tried to assist him became temporarily unconscious after disregarding training predicated on the time of useful consciousness after sudden depressurisation.
Air Conditioning and Pressurisation
On 6 June 2023, a Boeing 717-200 was on base leg about 10 nm from Hobart when chlorine fumes became evident on the flight deck. As the aircraft became fully established on final approach, the Captain recognised signs of cognitive impairment and handed control to the initially unaffected First Officer. Just before touchdown, he was similarly affected but was able to safely complete the landing and taxi in. The same aircraft had experienced a similar event two days earlier with no fault found. The Investigation determined that the operator’s procedures for responding to crew incapacitation in flight had been inadequate.
On 8 June 2016, a Boeing 737-800 en-route to Seville had already reverted to alternate automatic pressurisation control when this also failed. Manual system control was attempted but was unsuccessful so an emergency descent followed by diversion to Toulouse was then completed without further event. A similar pressurisation control fault had occurred earlier that day but had not been properly dealt with by an appropriately qualified engineer. Both system controllers were showing faults and were replaced as were a ruptured flexible hose and a series of malfunctioning drain valves. More reliable controllers and routine checking of system performance were recommended.
On 8 February 2022, a Boeing 767-300ER inbound to Madrid at FL340 experienced a failure of automatic pressurisation control followed almost three hours later by a failure of manual control and rapidly rising cabin altitude. An emergency was declared and descent made to FL120 where manual control was regained. The flight was completed without recurrence. The failure cause was found to have been water leaking from a tube with a broken clamp which, when it froze, had blocked the air conditioning outflow valve doors. Elements of the system design, scheduled maintenance requirements and fault detection were identified as contributing factors.
On 17 November 2021, after a Boeing 737-800 commenced initial descent into Patna from FL350, a cautionary alert indicating automatic pressurisation system failure was annunciated. When the initial actions of the prescribed non-normal procedure did not resolve the problem, the system outflow valve was fully opened, and a rapid depressurisation followed. After this incorrect action, the relevant crew emergency procedures were then not properly followed. It was further concluded that the captain had temporarily lost consciousness after a delay in donning his oxygen mask. The context for the mismanaged response was identified as outflow valve in-service failure.
On 23 February 2016, a Boeing 737-800 departing New Chitose encountered sudden-onset and unforecast heavy snowfall whilst taxiing out. When the right engine ran down and cabin crew reports of unusual smells in the cabin and flames coming from the right engine were received, it was decided that an emergency evacuation was required. During this evacuation three passengers were injured, one seriously. The engine fire was found to have been in the tailpipe and caused by an oil leak due to engine fan blade and compressor icing which had also led to vapourised engine oil contaminating the air conditioning system.
Autoflight
On 18 October 2019, a Boeing 787-9 descending to 4,500 feet to join the ILS for runway 25R at Hong Kong at 15 nm from touchdown failed to establish on the localiser. The autopilot was disconnected and the aircraft manually positioned onto the localiser from the north, establishing at 12 nm with terrain proximity not sufficient to activate the EGPWS. It was found that the deviation was attributable to an anomaly in the aircraft type Autopilot Flight Director System, and a corresponding Alert Service Bulletin was issued by Boeing to replace the faulty system component.
On 5 April 2019, a Boeing 737-500 crew declared an emergency shortly after departing Madrid Barajas after problems maintaining normal lateral, vertical or airspeed control of their aircraft in IMC. After two failed attempts at ILS approaches in unexceptional weather conditions, the flight was successfully landed at a nearby military airbase. The Investigation found that a malfunction which probably prevented use of the Captain’s autopilot found before departure was not documented until after the flight but could not find a technical explanation for inability to control the aircraft manually given that dispatch without either autopilot working is permitted.
On 9 January 2021, a Boeing 737-500 was climbing though 10,700 feet less than five minutes after departing Jakarta in daylight when it began to descend at an increasing rate from which no recovery occurred and 23 seconds later was destroyed by sea surface impact killing all 62 occupants. The Investigation concluded that the departure from controlled flight was unintentional and the result of the pilots’ inattention to their primary flight instruments when, during a turn with the autopilot engaged, an autothrottle malfunction created apparently unrecognised thrust asymmetry which culminated in a wing drop and a consequent loss of control.
On 20 July 2011, the flight crew of a Swiss European Avro RJ-100 on a positioning flight from Nuremburg to Zurich responded inappropriately to an unexpected ‘bank angle’ alert in IMC. Near loss of control followed during which a PAN was eventually declared. The situation was resolved by a belated actioning of the QRH checklist applicable to the failure symptoms experienced. The subsequent investigation attributed the event to inappropriate crew response to a failure of a single IRU and poor manual flying skill whilst the situation was resolved.
On 3 July 2017, an Airbus A319 sustained significant landing gear damage during the First Officer’s manual landing at Munich which recorded a vertical acceleration exceeding the threshold for a mandatory airworthiness inspection. That inspection found damage to nose and one main landing gear legs and, following Airbus advice, all three were replaced before release to service. The Investigation was unable to explain why neither pilot detected the incorrect pitch attitude and excessive rate of descent in time to take corrective action and noted that a reversion to manual flight during intermediate approach had been due to a technical malfunction.
Communications
On 6 February 2019, an Airbus A330-200 Captain’s Audio Control Panel (ACP) malfunctioned and began to emit smoke and electrical fumes after coffee was spilt on it. Subsequently, the right side ACP also failed, becoming hot enough to begin melting its plastic. Given the consequent significant communications difficulties, a turnback to Shannon was with both pilots taking turns to go on oxygen. The Investigation found that flight deck drinks were routinely served in unlidded cups with the cup size in use incompatible with the available cup holders. Pending provision of suitably-sized cups, the operator decided to begin providing cup lids.
On 29 February 2016, control of a 50 kg, 3.8 metre wingspan UAV was lost during a flight test being conducted in a Temporary Segregated Area in northern Belgium. The UAV then climbed to 4,000 feet and took up a south south-westerly track across Belgium and into northern France where it crash-landed after the engine stopped. The Investigation found that control communications had been interrupted because of an incorrectly manufactured co-axial cable assembly and a separate autopilot software design flaw not previously identified. This then prevented the default recovery process from working. A loss of prescribed traffic separation was recorded.
On 22nd August 1985, a B737-200 being operated by British Airtours, a wholly-owned subsidiary of British Airways, suffered an uncontained engine failure, with consequent damage from ejected debris enabling the initiation of a fuel-fed fire which spread to the fuselage during the rejected take off and continued to be fuel-fed after the aircraft stopped, leading to rapid destruction of the aircraft before many of the occupants had evacuated.
On 15 September 2006, an Easyjet Airbus A319, despatched under MEL provision with one engine generator inoperative and the corresponding electrical power supplied by the Auxiliary Power Unit generator, suffered a further en route electrical failure which included power loss to all COM radio equipment which could not then be re-instated. The flight was completed as flight planned using the remaining flight instruments with the one remaining transponder selected to the standard emergency code. The incident began near Nantes, France.
On 15 January 2009, an Embraer 195-200 being operated by UK Regional Airline Flybe was passing overhead Edinburgh UK at FL370 at night when communications problems between the flight deck and cabin crew occurred following the selection of emergency power as a precautionary measure after smoke, considered to possibly be of electrical origin, had been observed in the galley. An en route diversion with an uneventful outcome was accomplished.
Electrical Power
On 19 November 2020, the police operator of a DJI Matrice M210 UA lost control of it over Poole when it drifted beyond Visual Line Of Sight (VLOS) and communication ceased. It was subsequently damaged when colliding with a house in autoland mode. The Investigation found that a partial power failure had followed battery disconnection with its consequences not adequately communicated to the pilot. It faulted both the applicable UA User Manual content and the absence of sufficient UA status and detected wind information to the pilot. A failure to properly define VLOS was identified but not considered directly causal.
On 29 July 2011 an oxygen-fed fire started in the flight deck of an Egypt Air Boeing 777-200 about to depart from Cairo with most passengers boarded. The fire rapidly took hold despite attempts at extinguishing it but all passengers were safely evacuated via the still-attached air bridge access to doors 1L and 2L. The flight deck and adjacent structure was severely damaged. The Investigation could not conclusively determine the cause of the fire but suspected that wiring damage attributable to inadequately secured cabling may have provided a source of ignition for an oxygen leak from the crew emergency supply
On 31 January 2011, a Singapore Airlines Airbus A380-800 was in the cruise when there was sudden loud noise and signs of associated electrical smoke and potential burning in a toilet compartment with a corresponding ECAM smoke alert. After a fire extinguisher had been discharged into the apparent source, there were no further signs of fire or smoke. Subsequent investigation found signs of burning below the toilet floor and it was concluded that excessive current caused by a short circuit which had resulted from a degraded cable had been the likely cause, with over current protection limiting the damage caused by overheating.
On 7 January 2013, a battery fire on a Japan Air Lines Boeing 787-8 began almost immediately after passengers and crew had left the aircraft after its arrival at Boston on a scheduled passenger flight from Tokyo Narita. The primary structure of the aircraft was undamaged. Investigation found that an internal short circuit within a cell of the APU lithium-ion battery had led to uncontained thermal runaway in the battery leading to the release of smoke and fire. The origin of the malfunction was attributed to system design deficiency and the failure of the type certification process to detect this.
On 12 October 2018, the crew of a Boeing 737-400 already released to service under MEL conditions with an inoperative No 1 engine generator encountered a loss of services from the No 2 electrical system en-route to East Midlands which created a situation not addressed by QRH procedures. The flight was completed and both the new and existing defects were subsequently rectified relatively easily. The Investigation concluded that the operator involved appeared to be prioritising operational requirements over aircraft serviceability issues and made a range of Safety Recommendations aimed at improving company safety culture and the effectiveness of regulatory oversight.
Equipment/Furnishings
On 9 February 2023, a Boeing 777-200ER was en-route near Marseille when the cabin crew observed smoke coming from a rear galley oven which was spreading into the rear passenger cabin. After an immediate initial response and use of multiple Halon Fire extinguishers, the smoke ceased after about 20 minutes but the fumes remained. Although this meant no ongoing emergency existed, some cabin crew and passengers had experienced breathing difficulties and it was decided to return to Amsterdam. The cabin crew response to the situation was subsequently assessed as contrary to applicable procedures and relevant cabin crew training seemingly inadequate.
On 29 September 2017, the crew of an Airbus A320 detected a smell of burning plastic and simultaneously observed black smoke entering the flight deck near the right side rudder pedals. Completion of appropriate response procedures reduced the smoke and a diversion to Athens with a MAYDAY declared was without further event. The origin of the smoke and fumes was traced to the failure of the static inverter which was part of a batch which had been previously notified as faulty but not identified as such by the aircraft operator’s maintenance organisation which has since modified its relevant procedures.
On 12 July 2013 an unoccupied and unpowered Boeing 787-8, remotely parked at London Heathrow after an arrival earlier the same day caught fire. An investigation found that the source of the fire was an uncontained thermal runaway in the lithium-metal battery within an Emergency Locator Transmitter (ELT). Fifteen Safety Recommendations, all but one to the FAA, were made as a result of the Investigation.
On 11 March 2018, an Airbus AS350 engine failed during a commercial sightseeing flight and autorotation was initiated. The pilot then noticed that the floor-mounted fuel cut-off had been operated by part of the tether system of one of the five passengers but there was insufficient time to restore power. On water contact, the automatic floatation system operated asymmetrically and the helicopter submerged before the occupants could evacuate. Only the pilot was able to release his harness and escape because the unapproved adapted passenger harnesses had no quick release mechanism. The Investigation found systemic inadequacy of the operator s safety management system.
On 2 November 2017, the flight crew of an Airbus A320 climbing out of Cork detected a “strong and persistent” burning smell and after declaring a MAYDAY returned to Cork where confusing instructions from the crew resulted in a combination of the intended precautionary rapid disembarkation and an emergency evacuation using escape slides. The Investigation highlighted the necessity of clear and unambiguous communications with passengers which distinguish these two options and in particular noted the limitations in currently mandated pre flight briefings for passengers seated at over wing emergency exits.
Fire Protection
On 31 January 2011, a Singapore Airlines Airbus A380-800 was in the cruise when there was sudden loud noise and signs of associated electrical smoke and potential burning in a toilet compartment with a corresponding ECAM smoke alert. After a fire extinguisher had been discharged into the apparent source, there were no further signs of fire or smoke. Subsequent investigation found signs of burning below the toilet floor and it was concluded that excessive current caused by a short circuit which had resulted from a degraded cable had been the likely cause, with over current protection limiting the damage caused by overheating.
On 28 July 2011, 50 minutes after take off from Incheon, the crew of an Asiana Boeing 747-400F declared an emergency advising a main deck fire and an intention to divert to Jeju. The effects of the rapidly escalating fire eventually made it impossible to retain control and the aircraft crashed into the sea. The Investigation concluded that the origin of the fire was two adjacent pallets towards the rear of the main deck which contained Dangerous Goods shipments including Lithium ion batteries and flammable substances and that the aircraft had broken apart in mid-air following the loss of control.
On 25 May 2016, an Embraer ERJ 190 experienced a major electrical system failure soon after reaching its cruise altitude of FL 360. ATC were advised of problems and a descent to enable the APU to be started was made. This action restored most of the lost systems and the crew, not having declared an emergency, elected to complete their planned 400nm flight. The Investigation found that liquid contamination of an underfloor avionics bay had caused the electrical failure which had also involved fire and smoke without crew awareness because the smoke detection and air recirculation systems had been unpowered.
On 9 May 2010, Boeing 737-800 being operated by Swedish operator Viking Airlines on a public transport charter flight from Sharm el Sheikh, Egypt to Manchester UK and which had earlier suffered a malfunction which affected the level of redundancy in the aircraft pressurisation system, experienced a failure of the single air conditioning pack in use when over southern Austria and an emergency descent and en route diversion to Vienna were made. There were no injuries to any of the 196 occupants.
On 4 November 2010, a Qantas Airbus A380 climbing out of Singapore experienced a sudden and uncontained failure of one of its Rolls Royce Trent 900 engines which caused considerable collateral damage to the airframe and some of the aircraft systems. A PAN was declared and after appropriate crew responses including aircraft controllability checks, the aircraft returned to Singapore. The root cause of the failure was found to have been an undetected component manufacturing fault. The complex situation which resulted from the failure in flight was found to have exceeded the currently anticipated secondary damage from such an event.
Flight Controls
On 7 June 2021 an Embraer ERJ170 had just commenced its descent towards destination when both primary and secondary pitch trim systems failed resulting in excessive nose-down pitch control forces and an inoperative autopilot. The flight was completed without further event with the Pilot Flying using both hands on the control yoke to control pitch attitude manually. During the landing roll the nosewhweel steering system also failed. The pitch trim failure was attributed to probable jamming of the trim actuator due to water, possibly condensation, freezing within it. The steering system fault was attributed to a completely unrelated sensor failure.
On 15 January 2021, the pilot of a DJI Inspire 2 UAV being operated on a contracted aerial work task under a conditional permit lost control of it and, after it exitied the approved operating area, the UAV collided with the window of a hotel guest room causing consequential minor injuries to the occupant. The Investigation found that the loss of control was attributable to “strong magnetic interference” almost immediately after takeoff which caused the compass to feed unreliable data to the Internal Management Unit which destabilised its accelerometer and led to the loss of directional control which resulted in the collision.
On 14 November 2019, a Bombardier DHC8-400 experienced roll control difficulties after takeoff. These were manageable but it was decided a precautionary diversion should be made and this was accomplished without any significant roll control difficulty. The Investigation found that the right wing aileron control cable had failed due to undetected wear and that an option to fit an upgraded cable had not been taken. It also found the aircraft had a history of an intermittently unresponsive right aileron and discovered that signal noise filters which smoothed recorded data for all three primary flight control channels compromised FDR data value.
On 4 July 2019, the operator of an Alauda Airspeeder UAV lost control of it and it climbed to 8000 feet into controlled airspace at a designated holding pattern for London Gatwick before falling at 5000 fpm and impacting the ground close to housing. The Investigation was unable to establish the cause of the loss of control but noted that the system to immediately terminate a flight in such circumstances had also failed, thereby compromising public safety. The approval for operation of the UAV was found to been poorly performed and lacking any assessment of the airworthiness of the UAS.
On 8 October 2019, a BAe Jetstream 32 departing Münster/Osnabrück couldn’t be rotated and after beginning rejected takeoff from well above V1, the aircraft departed the side of the runway passing close to another aircraft at high speed before regaining the runway for the remainder of its deceleration. The Investigation noted that the flight was the first supervised line training sector for the very inexperienced First Officer but attributed the whole event to the Training Captain’s poor performance which had, apart many from other matters, led indirectly to the inability to rotate and to the subsequent directional control problem.
Fuel
On 31 October 2021, a ‘Fuel Imbalance’ message occurred on a Boeing 787-9 soon after departing Bangkok at night but attempted fuel transfer was unsuccessful. A ‘Fuel Disagree’ message subsequently appeared and use of available system checklists indicated that there was a fuel leak from the left engine or tank. Left engine shutdown was therefore accomplished and a MAYDAY diversion to an overweight landing at Goa followed. The Investigation determined that the leak was actually from the right side fuel tank and attributed crew misdiagnosis to limited fuel system malfunction checklists and gaps in crew guidance and training on fault diagnosis.
On 31 August 2019, all six occupants of an Airbus AS350 B3 being used for a sightseeing flight in northern Norway were killed after control was suddenly lost and the helicopter impacted the terrain below where the wreckage was immediately consumed by an intense fire. The Investigation found no airworthiness issues which could have led to the accident and concluded that the loss of control had probably been due to servo transparency, a known limitation of the helicopter type. However, it was concluded that it was the absence of a crash-resistant fuel system which had led to the fatalities.
On 27 July 2019, a fuel configuration advisory was annunciated on a Boeing 767-300 about to depart Auckland as a result of wing tank imbalance. Having established there was no evidence of a fuel leak, they planned to correct the imbalance in flight but then delayed this until it had exceeded the permitted limits. The fault was only verbally reported after flight and the aircraft continued to operate without centre tank use with maintenance remaining unaware of the fault for several days. The cause of imbalance was a fuel system fault subject to a crew response which was not followed.
On 9 May 2019, a Cessna 550 level at FL 350 experienced an unexplained left engine rundown to idle and the crew began descent and a diversion to Savannah. When the right engine also began to run down passing 8000 feet, an emergency was declared and the already-planned straight-in approach was successfully accomplished without any engine thrust. The ongoing Investigation has already established that the likely cause was fuel contamination resulting from the inadvertent mixing of a required fuel additive with an unapproved substance known to form deposits which impede fuel flow when they accumulate on critical fuel system components.
On 27 March 2016 an ATR 42-500 had just departed Esbjerg when the right engine flamed out. It was decided to complete the planned short flight to Billund but on the night IMC approach there, the remaining engine malfunctioned and lost power. The approach was completed and the aircraft evacuated after landing. The Investigation found the left engine failed due to fuel starvation resulting from a faulty fuel quantity indication probably present since recent heavy maintenance and that the right engine had emitted flames during multiple compressor stalls to which it was vulnerable due to in-service deterioration and hot section damage.
Hydraulic Power
On 7 April 2022, a Boeing 757-200F returning to San Jose after a left side hydraulics failure and MAYDAY declaration suddenly veered off the right hand side of the landing runway there during deceleration and passage over uneven ground led to landing gear collapse and significant fuselage structural damage. This runway excursion immediately followed simultaneous advancement of both thrust levers after their prior asymmetric movement earlier in the landing roll and resulted in high left thrust concurrent with idle thrust on the right. With no airworthiness aspect identified, the excursion was attributed to unintended thrust lever selection by the crew.
On 29 September 2019, an Airbus A330-200 received simultaneous indications of low pressure in two hydraulic systems soon after takeoff. An emergency was declared, and a return to land was followed by a stop on the runway due to a burst main wheel tyre. A manual valve for one of the hydraulic systems located in the left main gear wheel well had completely detached and impact-damaged a pipe in a nearby but separate hydraulic system. Both systems lost their fluid with valve detachment attributed to fatigue failure of the attachment screws, a risk addressed by an un-adopted non-mandatory Service Bulletin.
On 15 December 2019, an Airbus A330-200 turned back to Sydney shortly after departure when a major hydraulic system leak was annunciated. The return was uneventful until engine shutdown after clearing the runway following which APU use for air conditioning was followed by a gradual build up of hydraulic haze and fumes which eventually prompted an emergency evacuation. The Investigation found that fluid leaking from ruptured rudder servo hose had entered the APU air intake. The resulting evacuation was found to have been somewhat disorganised with this being attributed mainly to a combination of inadequate cabin crew procedures and training.
On 23 July 2011, a Boeing 737-300 being operated by Jet2.com on a passenger flight from Leeds/Bradford to Paris CDG experienced violent vibration from the main landing gear at touch down in normal day visibility on runway 27R at a normal speed off a stabilised approach. This vibration was accompanied by lateral acceleration that made directional control difficult but the aircraft was kept on the runway and at a speed of 75 knots, the vibrations abruptly stopped. Once clear of the runway, the aircraft was stopped and the engines shutdown prior to a tow to the gate. None of the 133 occupants were injured.
On 15 October 2015 a Boeing 747-300 experienced significant vibration from one of the engines almost immediately after take-off from Tehran Mehrabad. After the climb out was continued without reducing the affected engine thrust an uncontained failure followed 3 minutes later. The ejected debris caused the almost simultaneous failure of the No 4 engine, loss of multiple hydraulic systems and all the fuel from one wing tank. The Investigation attributed the vibration to the Operator's continued use of the engine without relevant Airworthiness Directive action and the subsequent failure to continued operation of the engine after its onset.
Ice and Rain Protection
On 9 August 2024, an ATR 72-500 at FL170 encountered weather conditions which led to airframe icing. Indicated airspeed decreased quickly without corrective action despite corresponding alerts and almost immediately after an ‘INCREASE SPEED’ alert during a turn, the aircraft stalled eventually entering a flat spin until impacting terrain in a residential area. Impact and a post-crash fire destroyed the aircraft and all occupants were killed. The Investigation is continuing.
On 22 March 2021, the pilots of a Boeing 747-8F which had just reached its initial cruise level after departing Dubai observed smoke and sparks coming from the window heating system and declared a PAN advising their intention to dump fuel and return to Dubai. With the faulty system switched off, this was accomplished without further event. It was found that the cause of the system malfunction was a design-related vulnerability with a history of recurrence which had not been adequately addressed by the aircraft manufacturer and the FAA as safety regulator following relevant NTSB Safety Recommendations made in 2007.
On 7 August 2020, a Boeing 737-800 making its second attempt to land at Calicut off a night ILS approach with a significant tailwind component became unstabilised and touched down approximately half way down the 2,700 metre-long wet table top runway and departed the end of it at 85 knots before continuing through the RESA and a fence and then dropping sharply onto a road. This caused the fuselage to separate into three pieces with 97 of the 190 occupants including both pilots being fatally or seriously injured and 34 others sustaining minor injuries. Significant fuel spillage occurred but there was no fire.
On 27 November 2017, an Embraer EMB 550 crew ignored a pre-takeoff indication of an inoperative airframe ice protection system despite taxiing out and taking off in icing conditions. The flight proceeded normally until approach to Paris Le Bourget when the Captain was unable to flare for touchdown at the normal speed and a 4g runway impact which caused a main gear leg to pierce the wing followed. The Investigation found that the crew had failed to follow relevant normal and abnormal operating procedures and did not understand how flight envelope protection worked or why it had activated on approach.
On 25 February 2017, an Airbus A320 left the side of the landing runway at Toronto when, for undetermined reasons, the Captain, as Pilot Flying, set up a drift to the right just before touchdown. This was then followed by a lateral runway excursion into wet grass in rain-reduced visibility which continued for 1,650 metres before the aircraft regained the runway and stopped. The Investigation noted that both the absence of runway centreline lighting and the aircraft operator’s policy of not activating the aircraft rain repellent system or applying the alternative hydrophobic windshield coating may have increased the excursion risk.
Indicating / Recording Systems
On 12 January 2022, an Embraer 170 and a Cessna 525 crossed tracks without the prescribed minimum separation, with neither ATC nor the Embraer crew being aware. Although ATC had issued acknowledged clearances to keep the Embraer 1,000 feet above the Cessna, it actually passed beneath it, violating minimum lateral separation. The underlying cause of the event was found to be an unrectified recurrent intermittent fault in one of the Cessna’s air data systems. Poor Cessna crew/controller communication during the event, systemically poor safety culture at its operator, and shortcomings in the Textron Aircraft Maintenance Manual were considered contributory.
On 10 June 2022, on reaching the planned FL330 cruise altitude abeam Meekatharra, a Boeing 737-400 crew observed a 340-foot difference between the two primary altimeter readings. The crew did not advise ATC of the breach of RVSM separation minima, but after identifying which instrument was in error, they returned uneventfully to their departure point, Perth. There, an engineering inspection found residue on all four electrically heated pitot-static probes. It was found that a few days earlier, an engine ground run done without first removing non-standard plastic probe covers had contaminated the probes, with cleaning performed prior to release to service.
On 22 September 2021, a Boeing 787-9 was found on arrival at its destination, Los Angeles, to have completed the 14½ hour flight from Melbourne with all four fan cowl static ports taped over. The crew had not observed any adverse consequence. The Investigation attributed the oversight to inadequate pre-flight maintenance and operational procedures and found that failure to identify the taping had resulted in the aircraft departing with reduced redundancy to the engine electronic control systems of both engines.
On 6 February 1996, a Boeing 757-200 took off from Puerto Plata at night despite awareness at the 80 knot check that the Captains altimeter was not working. Thereafter, the crew became confused as to their actual airspeed and lost control before the aircraft hit the sea surface less than five minutes after takeoff. The Investigation found that the Captain’s pitot probe was blocked and that the three pilots on the flight deck had become confused about which airspeed indications were reliable and had then not recovered from an aerodynamic stall which followed the wholly avoidable mismanagement of the aircraft flight path.
On 9 June 2021, an Airbus A320 Captain performing a relatively light weight and therefore rapid-acceleration takeoff from London Heathrow recognised as the standard 100 knot call was imminent that he had no speed indication so announced and performed a high speed rejected takeoff. Subsequent maintenance inspection found that the left pitot mast was blocked by the nest of a seasonally active solitary flying insect, noting that the aircraft had previously been parked for 24 hours on a non-terminal stand. Similar events, including another rejected takeoff, then followed and a comprehensive combined Investigation found all were of similar origin.
Landing Gear
On 29 September 2019, an Airbus A330-200 received simultaneous indications of low pressure in two hydraulic systems soon after takeoff. An emergency was declared, and a return to land was followed by a stop on the runway due to a burst main wheel tyre. A manual valve for one of the hydraulic systems located in the left main gear wheel well had completely detached and impact-damaged a pipe in a nearby but separate hydraulic system. Both systems lost their fluid with valve detachment attributed to fatigue failure of the attachment screws, a risk addressed by an un-adopted non-mandatory Service Bulletin.
On 18 June 2021, a Boeing 787-8 being operated by British Airways was being loaded for a cargo flight at Heathrow whilst line engineering carried out checks required to permit despatch with a deferred minor defect for later rectification. The check required cycling the landing gear with locking pins inserted so that only the bay doors cycled but when this was done, the nose gear retracted and the front of aircraft dropped to the ground causing significant damage to the airframe and minor injuries to two people. The nose gear downlock pin had inadvertently been inserted into the wrong hole.
On 3 December 2021, a Boeing 737MAX-8 released to service with antiskid and autobrake systems inoperative in accordance with Minimum Equipment List procedures then operated two sectors. On the return to Singapore, both left main landing gear tyres were sufficiently damaged during landing to cause the bursting of one and deflation of the other. The cause of this was failure to deploy the speedbrakes manually as required. A similar error on the previous sector did not have the same outcome because the relatively more positive touchdown enabled automatic speedbrake deployment and wheel spin was accompanied by simultaneous manual braking.
On 7 June 2021 an Embraer ERJ170 had just commenced its descent towards destination when both primary and secondary pitch trim systems failed resulting in excessive nose-down pitch control forces and an inoperative autopilot. The flight was completed without further event with the Pilot Flying using both hands on the control yoke to control pitch attitude manually. During the landing roll the nosewhweel steering system also failed. The pitch trim failure was attributed to probable jamming of the trim actuator due to water, possibly condensation, freezing within it. The steering system fault was attributed to a completely unrelated sensor failure.
On 6 August 2021, an Airbus A319 experienced uncommanded loss of both Flight Directors and the Flight Mode Annunciator and disconnection of both autopilot and autothrust in the climb. After levelling at FL350, significant inertial reference position inconsistencies were observed. A precautionary PAN was declared and the flight was completed. Investigation found that the cause was a momentary abnormal vertical shock load transferred to Inertial Reference System equipment through an overextended nose gear shock absorber by a sharp jolt during takeoff caused by a runway patch repair. Sensitivity of the particular inertial reference system installed on the aircraft was noted.
Navigation
On 6 August 2021, an Airbus A319 experienced uncommanded loss of both Flight Directors and the Flight Mode Annunciator and disconnection of both autopilot and autothrust in the climb. After levelling at FL350, significant inertial reference position inconsistencies were observed. A precautionary PAN was declared and the flight was completed. Investigation found that the cause was a momentary abnormal vertical shock load transferred to Inertial Reference System equipment through an overextended nose gear shock absorber by a sharp jolt during takeoff caused by a runway patch repair. Sensitivity of the particular inertial reference system installed on the aircraft was noted.
On 15 January 2021, the pilot of a DJI Inspire 2 UAV being operated on a contracted aerial work task under a conditional permit lost control of it and, after it exitied the approved operating area, the UAV collided with the window of a hotel guest room causing consequential minor injuries to the occupant. The Investigation found that the loss of control was attributable to “strong magnetic interference” almost immediately after takeoff which caused the compass to feed unreliable data to the Internal Management Unit which destabilised its accelerometer and led to the loss of directional control which resulted in the collision.
On 12 July 2013 an unoccupied and unpowered Boeing 787-8, remotely parked at London Heathrow after an arrival earlier the same day caught fire. An investigation found that the source of the fire was an uncontained thermal runaway in the lithium-metal battery within an Emergency Locator Transmitter (ELT). Fifteen Safety Recommendations, all but one to the FAA, were made as a result of the Investigation.
On 27 June 2016, an Airbus A319 narrowly avoided a mid-air collision with an AS532 Cougar helicopter whose single transponder had failed earlier whilst conducting a local pre-delivery test flight whilst both were positioning visually as cleared to land at Marseille and after the helicopter had also temporarily disappeared from primary radar. Neither aircraft crew had detected the other prior to their tracks crossing at a similar altitude. The Investigation attributed the conflict to an inappropriate ATC response to the temporary loss of radar contact with the helicopter aggravated by inaccurate position reports and non-compliance with the aerodrome circuit altitude by the helicopter crew.
On 25 May 2016, an Embraer ERJ 190 experienced a major electrical system failure soon after reaching its cruise altitude of FL 360. ATC were advised of problems and a descent to enable the APU to be started was made. This action restored most of the lost systems and the crew, not having declared an emergency, elected to complete their planned 400nm flight. The Investigation found that liquid contamination of an underfloor avionics bay had caused the electrical failure which had also involved fire and smoke without crew awareness because the smoke detection and air recirculation systems had been unpowered.
Oxygen
On 29 July 2011 an oxygen-fed fire started in the flight deck of an Egypt Air Boeing 777-200 about to depart from Cairo with most passengers boarded. The fire rapidly took hold despite attempts at extinguishing it but all passengers were safely evacuated via the still-attached air bridge access to doors 1L and 2L. The flight deck and adjacent structure was severely damaged. The Investigation could not conclusively determine the cause of the fire but suspected that wiring damage attributable to inadequately secured cabling may have provided a source of ignition for an oxygen leak from the crew emergency supply
On 24 August 2001, an Air Transat Airbus A330-200 eastbound across the North Atlantic at night experienced a double-engine flameout after which Lajes on Terceira Island in the Azores was identified as the best diversion and a successful glide approach and landing there was subsequently achieved. The Investigation found that the flameouts had been the result of fuel exhaustion after a fuel leak from the right engine caused by a pre flight maintenance error. Fuel exhaustion was found to have occurred because the flight crew did not perform the QRH procedure applicable to an in-flight fuel leak.
On 22 March 2007, climbing out of Stockholm Sweden, the crew of a Malmö Aviation Avro RJ100 failed to notice that the aircraft was not pressurised until cabin crew advised them of automatic cabin oxygen mask deployment.
On 25 July 2008, a Boeing 747 suffered a rapid depressurisation of the cabin following the sudden failure of an oxygen cylinder, which had ruptured the aircraft's pressure hull. The incident occurred 475 km north-west of Manila, Philippines.
Airborne Auxiliary Power (APU)
On 15 December 2019, an Airbus A330-200 turned back to Sydney shortly after departure when a major hydraulic system leak was annunciated. The return was uneventful until engine shutdown after clearing the runway following which APU use for air conditioning was followed by a gradual build up of hydraulic haze and fumes which eventually prompted an emergency evacuation. The Investigation found that fluid leaking from ruptured rudder servo hose had entered the APU air intake. The resulting evacuation was found to have been somewhat disorganised with this being attributed mainly to a combination of inadequate cabin crew procedures and training.
On 20 January 2015, The APU of a Fokker 100 being routinely de-iced prior to departing Nuremburg oversped as a result of the ignition of ingested de-icing fluid in the APU. This led to its explosive uncontained failure as the result of which ejected debris entered the aft cabin and smoke occurred. No occupants were injured and all were promptly disembarked. The Investigation found that the de-icing contractor involved had not followed manufacturer-issued aircraft-specific de-icing procedures and in the continued absence of any applicable safety regulatory oversight of ground de-icing activity, corresponding Safety Recommendations were made.
On 26 June 2016, thick white smoke suddenly appeared in the cabin of a fully loaded Airbus A330-300 prior to engine start with the door used for boarding still connected to the air bridge. An emergency evacuation initiated by cabin crew was accomplished without injury although amidst some confusion due to a brief conflict between flight crew and cabin crew instructions. The Investigation found that the smoke had been caused when an APU seal failed and hot oil entered the bleed air supply and pyrolysed. Safety Recommendations in respect of both crew communication and procedures and APU auto-shutdown were made.
On 25 September 2001, an Embraer 145 in descent to Manchester sustained a low power lightning strike which was followed, within a few seconds, by the left engine stopping without failure annunciation. A successful single engine landing followed. The Investigation concluded that the cause of failure of the FADEC-controlled AE3007 engine (which has no surge recovery logic) was the aero-thermal effects of the strike to which all aircraft with relatively small diameter fuselages and close mounted engines are vulnerable. It was considered that there was a risk of simultaneous double engine flameout in such circumstances which was impossible to quantify.
On 28 July 2013, with passengers still boarding an Air France Boeing 777-300, an abnormal 'burnt' smell was detected by the crew and then thin smoke appeared in the cabin. A MAYDAY was declared and the Captain made a PA telling the cabin crew to evacuate the passengers via the doors, only via the doors. The resulting evacuation process was confused but eventually completed. The Investigation attributed the confused evacuation to the way it had been ordered and established that a fault in the APU had caused the smoke and fumes which had the potential to be toxic.
Propellers
On 26 November 2020, abnormally low left-engine propeller speed was observed as an ATR 42-300 descended into Naujaat with other engine parameters normal. Relevant abnormal procedures were not consulted, and on reverse pitch selection after touchdown, neither pilot noticed the left engine's low prop pitch indication was not illuminated. The aircraft veered off the right side of the runway into snow, and the aircraft was substantially damaged and the captain seriously injured. The accident was attributed to the crew’s initial failure to consult applicable abnormal procedures, and then failure to make the required check of symmetric reverse pitch before selection.
On 7 December 2016, the crew of an ATR 42-500 lost control after airworthiness-related complications followed shutdown of the left engine whilst in the cruise and high speed terrain impact followed. The Investigation concluded that three pre-existing faults with the left engine and its propeller control mechanism had led to a loss of power which had necessitated its shutdown but that these faults had then caused much higher left side drag than would normally result from an engine shutdown and made it progressively more difficult to maintain control. Recovery from a first loss of control was followed by another without recovery.
On 17 March 2017, uncommanded engine indications on a Saab 340B en route to Sydney were followed by vibration of the right engine after which, as the crew commenced right engine shutdown, its propeller assembly separated from the engine. A PAN was declared and the flight subsequently reached Sydney without further event. The Investigation found that the propeller gearbox shaft had fractured because of undetected internal fatigue cracking in the shaft. Applicable in-service shaft inspection procedures were found to be inadequate and mandatory enhancements to these procedures have since been introduced.
On 28 November 2013, a Saab 2000 departing Lugano suffered an engine failure for no apparent reason and the crew determined that diversion to Milan was preferable to return to Lugano or continued climb over high terrain to reach intended destination Zurich. The Investigation found that the loss of engine power experienced was due to a double FADEC failure with a transient malfunction of one channel resulting in an automated transfer to the other channel which already had an undetected permanent fault attributable to maintenance error. It was noted that the airline involved had contracted out all continuing airworthiness responsibilities.
On 9 January 2015, a Saab 340B encountered a flock of medium-sized birds soon after decelerating through 80 knots during its landing roll at Moruya. A subsequent flight crew inspection in accordance with the prevailing operator procedures concluded that the aircraft could continue in service but after completion of the next flight, a propeller blade tip was found to be missing. The Investigation concluded that the blade failure was a result of the earlier bird impact and found that airline procedures allowing pilots to determine continued airworthiness after a significant birdstrike had unknowingly been invalid.
Rotors
On 22 February 2008, a Eurocopter AS332 L2 Super Puma flying from an offshore oil platform to Aberdeen was struck by lightning. There was no apparent consequence and so, although this event required a landing as soon as possible, the commander decided to continue the remaining 165nm to the planned destination which was achieved uneventfully. Main rotor blade damage including some beyond repairable limits was subsequently discovered. The Investigation noted evidence indicating that this helicopter type had a relatively high propensity to sustain lightning strikes but noted that, despite the risk of damage, there was currently no adverse safety trend.
On 22 October 2012, the crew of a Eurocopter EC225 LP on a flight from Aberdeen to an offshore platform received an indication that the main gearbox (MGB) lubrication system had failed. Shortly after selecting the emergency lubrication system, that system also indicated failure and the crew responded in accordance with the QRH drill to “land immediately” by carrying out a successful controlled ditching. The ongoing investigation has found that there had been a mechanical failure within the MGB but that the emergency lubrication system had, contrary to indications, been functioning normally.
On 12 August 2015, a Sikorsky S76C crew on a flight from an offshore platform to Lagos lost control of their aircraft after a sudden uncommanded pitch up, yaw and roll began and 12 seconds later it crashed into water in a suburb of Lagos killing both pilots and four of the 10 passengers. The Investigation concluded that the upset had been caused by a critical separation within the main rotor cyclic control system resulting from undetected wear at a point where there was no secondary mechanical locking system such as a locking pin or a wire lock to maintain system integrity.
On 27 October 2018, a single-pilot Leonardo AW169 helicopter lifted off from within the Leicester City football stadium. After an almost immediate failure of the tail rotor control system, control was lost and ground impact and a post-crash fire resulted in fatal injuries to all five occupants. Seizure of the tail rotor duplex bearing was found to have initiated failures that culminated in the unrecoverable loss of control of the tail rotor blade pitch angle. This failure was a direct consequence of gross failures in risk assessment at the aircraft manufacturer and an inadequate type certification process.
On 28 December 2016, yaw control was lost during touchdown of a Sikorsky S92A landing on a North Sea offshore platform and it almost fell into the sea. The Investigation found that the loss of control was attributable to the failure of the Tail Rotor Pitch Change Shaft bearing which precipitated damage to the associated control servo. It was also found that despite HUMS monitoring being in place, it had been ineffective in proactively alerting the operator to the earlier stages of progressive bearing deterioration which could have ensured the helicopter was grounded for rectification before the accident occurred.
Engine - General
On 6 April 2022, a Boeing 767-300 lost left engine oil pressure whilst eastbound and passing south of Cork and diverted to Shannon after declaring an emergency on account of intended engine shutdown. During the subsequent taxi in, a fire was observed and extinguished and the aircraft towed to the terminal after an initial fire service request for evacuation had been withdrawn. An engine oil leak from a chip detector which had been routinely inspected by a company engineer prior to departure but not reinstalled correctly was found to have caused the leak and thus the loss of oil pressure.
On 8 April 2022, an Airbus A320 made a multiple bounce touchdown at Copenhagen followed by thrust reverser deployment. The Captain rejected the landing and began a go-around but as the left main gear had bounced and was not on the ground when thrust was set, the left engine reverser did not stow. Full aircraft control was briefly lost and a runway excursion narrowly avoided before a recovery to a single engine MAYDAY circuit and landing followed. Engine software design prevented thrust reverser stowage without weight on wheels which was why rejected landings after reverser deployment were prohibited.
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 12 September 2021, a Boeing 777-300 in cruise at FL380 and approaching Oman from the east at night experienced a sudden left engine failure. The engine was shut down, a PAN call was made, and the crew diverted to Muscat rather than completing the intended flight to Abu Dhabi. An off-wing examination of the GE90 engine found that the hydromechanical unit of the accessory gearbox had malfunctioned in a way which allowed fuel to mix with the engine oil. This failure had not been anticipated in the applicable Fault Identification Manual, which was amended accordingly.
On 10 August 2019, the left Rolls Royce Trent 1000 engine of a Boeing 787-8 just airborne from Rome Fiumicino suddenly malfunctioned and was shut down. A MAYDAY was declared, and the flight returned for an overweight landing during which all four left main gear tyres deflated. The underlying cause of the engine failure was found to have been intermediate-pressure turbine blade detachment attributable to previously identified serviceability issues. Wider concerns were identified in relation to underlying engine certification standards and to the hazard created by ejection of large quantities of engine debris into a densely populated area.
Engine Fuel and Control
On 16 September 2019, an ATR 72-200 diverted to Itaituba when landing at its intended destination Manaus was prevented by its unexpected closure due to an aircraft accident. During this diversion, intermittent indications of low fuel quantity were annunciated and one engine subsequently ran down on final approach and the other whilst backtracking after landing. It was found that due to a series of undetected faults in the aircraft’s fuel quantity sensing system, the flight deck indications of fuel tank contents were over reading and the low fuel indication system was also malfunctioning for the same reason.
On 20 July 2021, a Boeing 747-8F experienced a series of problems with excessive engine speed and fire affecting the left outboard engine soon after takeoff from Hong Kong. Although the engine was shut down, the fire continued until just before landing. About twenty minutes after landing, trapped residual leaked fuel then auto-ignited, and that fire was quickly extinguished. The origin of the engine malfunction and continuing airborne fire was identified as improper installation of a component in the engine’s Fuel Metering Unit at build, which caused a fuel leak that was the sole origin of the engine malfunction.
On 31 December 2020, an Airbus A330-200 identified a fuel leak during a routine top-of-climb check but instead of following the prescribed engine shutdown and leak isolation procedure and then landing as soon as possible, the crew had continued on track until diverting to N’Djaména over 90 minutes later by which time nearly six tonnes of fuel was missing. The leak was caused by an incorrectly assembled connection at the pylon/engine interface. The flight crew’s procedural non-compliance was identified as having introduced an avoidable fire risk and been indicative of a systemically weak safety culture at the airline concerned.
On 16 March 2020, a PW150A-powered Bombardier DHC8-400 crew declared a PAN and turned back to Port Moresby after abnormal fumes and (much later) some visible ‘smoke’ which had become apparent after takeoff began to intensify causing some passengers breathing difficulties. Once clear of the landing runway, a precautionary rapid disembarkation was completed. The Investigation found that the source of the smoke/fumes was oil leaking from a failed right engine bearing seal. The failure was found to have occurred ahead of the recommended inspection interval for the seal concerned, a risk which engine manufacturer Pratt & Whitney Canada was aware of.
On 18 April 2018, an engine fire warning was annunciated on an Airbus 330-300 which had just taken off from Atlanta. The warning remained after engine shutdown but was eventually replaced by a fire detection caution. Although not visible to the crew, a continued/reignited engine fire was subsequently seen by ATC on final approach and extinguished after landing. The Investigation concluded that the avoidable delay in the return to land had considerably increased the engine and pylon damage and noted that continuation of the fire had been facilitated by hydraulic fluid passing through a valve held partly open by debris.
Bleed Air
On 18 March 2020, a Fokker 100 en-route to Port Moresby experienced a failure of the cabin pressurisation and air conditioning system due to a complete failure of the bleed air system. An emergency descent and a PAN were declared and a diversion to Madang completed. The Investigation noted unscheduled work on the bleed air system had occurred prior to the departure of the flight and that long running problems with this system had not been satisfactorily resolved until after the investigated occurrence when four malfunctioning components had finally been systematically identified and replaced.
On 15 August 2018, a Boeing 737-300SF crew concerned about a small residual pressure in a bleed air system isolated after a fault occurred en-route then sought and were given non-standard further troubleshooting guidance by company maintenance which, when followed, led directly and indirectly to additional problems including successive incapacitation of both pilots and a MAYDAY diversion. The Investigation found that the aircraft concerned was carrying a number of relevant individually minor undetected defects which meant the initial crew response was not completely effective and prompted a request for in-flight assistance which was unnecessary and led to the further outcomes.
On 23 September 2019, the flight crew of an Airbus A320 on approach to London Heathrow detected strong acrid fumes on the flight deck and after donning oxygen masks completed the approach and landing, exited the runway and shut down on a taxiway. After removing their masks, one pilot became incapacitated and the other unwell and both were taken to hospital. The other occupants, all unaffected, were disembarked to buses. The very comprehensive investigation was unable to establish the origin of the fumes but did identify a number of circumstantial factors which corresponded to those identified in previous similar events.
On 28 February 2019, an Embraer E195 abandoned takeoff from Exeter when fight deck fumes/smoke accompanied thrust applied against the brakes. When informed of similar conditions in the cabin, the Captain ordered an emergency evacuation. Some passengers using the overwing exits re-entered the cabin after becoming confused as to how to leave the wing. The Investigation attributed the fumes to an incorrectly-performed engine compressor wash arising in a context of poorly-managed maintenance and concluded that guidance on overwing exit use had been inadequate and that the 1.8 metre certification height limit for exits without evacuation slides should be reduced.
On 19 October 2012, a Jet2-operated Boeing 737-800 departing Glasgow made a high speed rejected take off when a strange smell became apparent in the flight deck and the senior cabin crew reported what appeared to be smoke in the cabin. The subsequent emergency evacuation resulted in one serious passenger injury. The Investigation was unable to conclusively identify a cause of the smoke and the also- detected burning smells but excess moisture in the air conditioning system was considered likely to have been a factor and the Operator subsequently made changes to its maintenance procedures.
Other
On 11 December 2019, a Bombardier BD700 Global 6000 making a night landing at Liverpool suffered a nose wheel steering failure shortly after touchdown. The crew were unable to prevent the aircraft departing the side of the runway into a grassed area where it stopped, undamaged, in mud. The Investigation found that the crew response was contrary to that needed for continued directional control but also that no pilot training or QRH procedure covered such a failure occurring at high speed nor was adequate guidance available on mitigating the risk of inadvertent opposite brake application during significant rudder deflection.
On 13 April 2019, an experienced Cessna 525 pilot almost lost control shortly after takeoff from Bournemouth when a recently installed performance enhancement system malfunctioned. After a six minute flight involving a potentially hazardous upset and recovery of compromised control, the turn back was successful. The Investigation found that although the pilot was unaware of the supplementary procedures supporting the modification, these did not adequately address possible failure cases. Also, certification flight tests prior to modification approval did not identify the severity of some possible failure outcomes and corresponding Safety Recommendations were made to the system manufacturer and safety regulators.
On 12 October 2018, the crew of a Boeing 737-400 already released to service under MEL conditions with an inoperative No 1 engine generator encountered a loss of services from the No 2 electrical system en-route to East Midlands which created a situation not addressed by QRH procedures. The flight was completed and both the new and existing defects were subsequently rectified relatively easily. The Investigation concluded that the operator involved appeared to be prioritising operational requirements over aircraft serviceability issues and made a range of Safety Recommendations aimed at improving company safety culture and the effectiveness of regulatory oversight.
On 2 November 2017, the flight crew of an Airbus A320 climbing out of Cork detected a “strong and persistent” burning smell and after declaring a MAYDAY returned to Cork where confusing instructions from the crew resulted in a combination of the intended precautionary rapid disembarkation and an emergency evacuation using escape slides. The Investigation highlighted the necessity of clear and unambiguous communications with passengers which distinguish these two options and in particular noted the limitations in currently mandated pre flight briefings for passengers seated at over wing emergency exits.
On 19 June 2016, a BAe 146-300 landed long at Khark Island and overran the end of the runway at speed with the aircraft only stopping because the nose landing gear collapsed on encountering uneven ground. The Investigation attributed the accident - which caused enough structural damage for the aircraft to be declared a hull loss - entirely to the decisions and actions of the aircraft commander who failed to go around from an unstabilised approach, landed long and then did not ensure maximum deceleration was achieved. The monitoring role of the low experience First Officer was ineffective.
Emergency Evacuation
On 18 November 2022, the crew of an Airbus A320neo about to become airborne as it departed Lima were unable to avoid a high-speed collision with an airport fire appliance, which unexpectedly entered the runway. The impact wrecked the vehicle, killing two of its three occupants, and a resultant fuel-fed fire severely damaged the aircraft, although with no fatalities amongst its 107 occupants. The vehicle was found to have entered the runway without clearance primarily as a consequence of inadequate briefing for an exercise to validate emergency access times from a newly relocated airport fire station.
On 12 March 2009, a Sikorsky S-92A crew heading offshore from St. John's, Newfoundland declared an emergency and began a return after total loss of main gear box oil pressure but lost control during an attempted ditching. The Investigation found that all oil had been lost after two main gear box securing bolts had sheared. It was noted that ambiguity had contributed to crew misdiagnosis the cause and that the ditching had been mishandled. Sea States beyond the capability of Emergency Flotation Systems and the limited usefulness of personal Supplemental Breathing Systems in cold water were identified as Safety Issues.
On 8 March 2017, a Boeing MD83 departing Ypsilanti could not be rotated and the takeoff had to be rejected from above V1. The high speed overrun which followed substantially damaged the aircraft but evacuation was successful. The Investigation found that the right elevator had been locked in a trailing-edge-down position as a result of damage caused to the aircraft by high winds whilst it was parked unoccupied for two days prior to the takeoff. It was noted that on an aircraft with control tab initiated elevator movement, this condition was undetectable during prevailing pre flight system inspection or checks.
On 4 October 2014, the fracture of a hydraulic hose during an A330-200 pushback at night at Karachi was followed by dense fumes in the form of hydraulic fluid mist filling the aircraft cabin and flight deck. After some delay, during which a delay in isolating the APU air bleed exacerbated the ingress of fumes, the aircraft was towed back onto stand and an emergency evacuation completed. During the return to stand, a PBE unit malfunctioned and caught fire when one of the cabin crew attempted to use it which prevented use of the exit adjacent to it for evacuation.
On 22 August 2015 the pilot of a civil-operated Hawker Hunter carrying out a flying display sequence at Shoreham failed to complete a loop and partial roll manoeuvre and the aircraft crashed into road traffic unrelated to the airshow and exploded causing multiple third party fatalities and injuries. The Investigation found that the pilot had failed to enter the manoeuvre correctly and then failed to abandon it when it should have been evident that it could not be completed. It was concluded that the wider context for the accident was inadequate regulatory oversight of UK civil air display flying risk management.
Rotary Aircraft Transmission
On 12 March 2009, a Sikorsky S-92A crew heading offshore from St. John's, Newfoundland declared an emergency and began a return after total loss of main gear box oil pressure but lost control during an attempted ditching. The Investigation found that all oil had been lost after two main gear box securing bolts had sheared. It was noted that ambiguity had contributed to crew misdiagnosis the cause and that the ditching had been mishandled. Sea States beyond the capability of Emergency Flotation Systems and the limited usefulness of personal Supplemental Breathing Systems in cold water were identified as Safety Issues.
On 29 April 2016, an Airbus EC225 Super Puma main rotor detached without warning en-route to Bergen. Control was lost and it crashed and was destroyed. Rotor detachment was attributed to undetected development of metal fatigue in the same gearbox component which caused an identical 2009 accident to a variant of the same helicopter type. Despite this previous accident, the failure mode involved had not been properly understood or anticipated. The investigation identifies significant lessons to be learned related to gearbox design, risk assessment, fatigue evaluation, gearbox condition monitoring, type certification and continued airworthiness, which may also be valid for other helicopter types.
Group 2 - Contributors
Maintenance Error (valid guidance available)
On 6 April 2022, a Boeing 767-300 lost left engine oil pressure whilst eastbound and passing south of Cork and diverted to Shannon after declaring an emergency on account of intended engine shutdown. During the subsequent taxi in, a fire was observed and extinguished and the aircraft towed to the terminal after an initial fire service request for evacuation had been withdrawn. An engine oil leak from a chip detector which had been routinely inspected by a company engineer prior to departure but not reinstalled correctly was found to have caused the leak and thus the loss of oil pressure.
On 5 January 2024, a Boeing 737-9 which had just departed Portland was climbing through 14,800 feet when there was a loud bang followed by a rapid decompression. The cause - the loss of a fuselage plug fitted at an unused door location - was immediately obvious. An emergency was declared and a landing back at Portland was made after a total of twenty minutes airborne. The Investigation is continuing but has found that the fuselage plug involved was installed without being properly secured and noted that the aircraft had only recently been delivered new to the operator.
On 20 July 2021, a Boeing 747-8F experienced a series of problems with excessive engine speed and fire affecting the left outboard engine soon after takeoff from Hong Kong. Although the engine was shut down, the fire continued until just before landing. About twenty minutes after landing, trapped residual leaked fuel then auto-ignited, and that fire was quickly extinguished. The origin of the engine malfunction and continuing airborne fire was identified as improper installation of a component in the engine’s Fuel Metering Unit at build, which caused a fuel leak that was the sole origin of the engine malfunction.
On 25 November 2021, a Fokker F50 departing Helsinki experienced an engine malfunction that resulted in an uncommanded propeller feathering. The associated engine continued to run until shutdown, during which time it began to overspeed. The aircraft landed safely, but the failure experienced was untrained, and this led to both direct and indirect consequences that resulted in a suboptimal crew response to the emergency. The Investigation also highlighted opportunities to improve aspects of the air traffic control emergency response during such emergencies and identified language proficiency certification issues.
On 10 June 2022, on reaching the planned FL330 cruise altitude abeam Meekatharra, a Boeing 737-400 crew observed a 340-foot difference between the two primary altimeter readings. The crew did not advise ATC of the breach of RVSM separation minima, but after identifying which instrument was in error, they returned uneventfully to their departure point, Perth. There, an engineering inspection found residue on all four electrically heated pitot-static probes. It was found that a few days earlier, an engine ground run done without first removing non-standard plastic probe covers had contaminated the probes, with cleaning performed prior to release to service.
Maintenance Error (invalid guidance available)
On 25 March 2018, an ATR 42-500 main landing gear bay door weighing 15 kg detached shortly after a night descent had begun but this was unknown until the flight arrived at Aurillac. The Investigation found that the root cause of the detachment was a loose securing nut which had triggered a sequence of secondary failures within a single flight which culminated in the release of the door. It was concluded that the event highlighted specific and systemic weakness in relevant airworthiness documentation and practice in relation to the lost door and the use of fasteners on this aircraft type generally.
On 28 February 2019, an Embraer E195 abandoned takeoff from Exeter when fight deck fumes/smoke accompanied thrust applied against the brakes. When informed of similar conditions in the cabin, the Captain ordered an emergency evacuation. Some passengers using the overwing exits re-entered the cabin after becoming confused as to how to leave the wing. The Investigation attributed the fumes to an incorrectly-performed engine compressor wash arising in a context of poorly-managed maintenance and concluded that guidance on overwing exit use had been inadequate and that the 1.8 metre certification height limit for exits without evacuation slides should be reduced.
On 19 October 2012, a Jet2-operated Boeing 737-800 departing Glasgow made a high speed rejected take off when a strange smell became apparent in the flight deck and the senior cabin crew reported what appeared to be smoke in the cabin. The subsequent emergency evacuation resulted in one serious passenger injury. The Investigation was unable to conclusively identify a cause of the smoke and the also- detected burning smells but excess moisture in the air conditioning system was considered likely to have been a factor and the Operator subsequently made changes to its maintenance procedures.
On 31 January 2011, a Singapore Airlines Airbus A380-800 was in the cruise when there was sudden loud noise and signs of associated electrical smoke and potential burning in a toilet compartment with a corresponding ECAM smoke alert. After a fire extinguisher had been discharged into the apparent source, there were no further signs of fire or smoke. Subsequent investigation found signs of burning below the toilet floor and it was concluded that excessive current caused by a short circuit which had resulted from a degraded cable had been the likely cause, with over current protection limiting the damage caused by overheating.
On 10 January 2011, a Europe Airpost Boeing 737-300 taking off from Montpelier after repainting had just rotated for take off when the leading edge slats extended from the Intermediate position to the Fully Extended position and the left stick shaker was activated as a consequence of the reduced stalling angle of attack. Initial climb was sustained and soon afterwards, the slats returned to their previous position and the stick shaker activation stopped. The unexpected configuration change was attributed to paint contamination of the left angle of attack sensor, the context for which was inadequate task guidance.
Inadequate Maintenance Schedule
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 7 June 2021 an Embraer ERJ170 had just commenced its descent towards destination when both primary and secondary pitch trim systems failed resulting in excessive nose-down pitch control forces and an inoperative autopilot. The flight was completed without further event with the Pilot Flying using both hands on the control yoke to control pitch attitude manually. During the landing roll the nosewhweel steering system also failed. The pitch trim failure was attributed to probable jamming of the trim actuator due to water, possibly condensation, freezing within it. The steering system fault was attributed to a completely unrelated sensor failure.
On 2 July 2017, the left engine of a Bombarier CRJ 700A exiting the runway after landing at Denver caught fire and continued burning after the aircraft had been stopped on the taxiway and the engine shut down. The Investigation found that the fuel supply to the fuel-operated engine performance valve had failed and the quantity of fuel which then leaked had overwhelmed the engine cowl drain capacity and ignited. A history of similar failures was found and this one resulted in the introduction of additional mandatory in-serviced checks pending the replacement of the valve concerned with an improved design.
On 23 February 2020, a Bombardier Challenger 605 making a flapless landing after a system failure during descent briefly lost control when reverse thrust selection after a normal touchdown was followed by the aircraft becoming airborne before stick push activation was followed by a hard second touchdown. Structural and abrasion fuselage damage was caused. The Investigation attributed the flap failure to corrosion within the specified maintenance inspection interval and the brief loss of control during landing to a combination of inadequate crew preparation for the landing and the fact that simulator replication of aircraft handling did not correspond to reality.
On 7 December 2016, the crew of an ATR 42-500 lost control after airworthiness-related complications followed shutdown of the left engine whilst in the cruise and high speed terrain impact followed. The Investigation concluded that three pre-existing faults with the left engine and its propeller control mechanism had led to a loss of power which had necessitated its shutdown but that these faults had then caused much higher left side drag than would normally result from an engine shutdown and made it progressively more difficult to maintain control. Recovery from a first loss of control was followed by another without recovery.
Inadequate Maintenance Inspection
On 16 September 2019, an ATR 72-200 diverted to Itaituba when landing at its intended destination Manaus was prevented by its unexpected closure due to an aircraft accident. During this diversion, intermittent indications of low fuel quantity were annunciated and one engine subsequently ran down on final approach and the other whilst backtracking after landing. It was found that due to a series of undetected faults in the aircraft’s fuel quantity sensing system, the flight deck indications of fuel tank contents were over reading and the low fuel indication system was also malfunctioning for the same reason.
On 8 June 2016, a Boeing 737-800 en-route to Seville had already reverted to alternate automatic pressurisation control when this also failed. Manual system control was attempted but was unsuccessful so an emergency descent followed by diversion to Toulouse was then completed without further event. A similar pressurisation control fault had occurred earlier that day but had not been properly dealt with by an appropriately qualified engineer. Both system controllers were showing faults and were replaced as were a ruptured flexible hose and a series of malfunctioning drain valves. More reliable controllers and routine checking of system performance were recommended.
On 8 February 2022, a Boeing 767-300ER inbound to Madrid at FL340 experienced a failure of automatic pressurisation control followed almost three hours later by a failure of manual control and rapidly rising cabin altitude. An emergency was declared and descent made to FL120 where manual control was regained. The flight was completed without recurrence. The failure cause was found to have been water leaking from a tube with a broken clamp which, when it froze, had blocked the air conditioning outflow valve doors. Elements of the system design, scheduled maintenance requirements and fault detection were identified as contributing factors.
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 10 June 2022, on reaching the planned FL330 cruise altitude abeam Meekatharra, a Boeing 737-400 crew observed a 340-foot difference between the two primary altimeter readings. The crew did not advise ATC of the breach of RVSM separation minima, but after identifying which instrument was in error, they returned uneventfully to their departure point, Perth. There, an engineering inspection found residue on all four electrically heated pitot-static probes. It was found that a few days earlier, an engine ground run done without first removing non-standard plastic probe covers had contaminated the probes, with cleaning performed prior to release to service.
Inadequate QRH Drills
On 12 January 2022, an Embraer 170 and a Cessna 525 crossed tracks without the prescribed minimum separation, with neither ATC nor the Embraer crew being aware. Although ATC had issued acknowledged clearances to keep the Embraer 1,000 feet above the Cessna, it actually passed beneath it, violating minimum lateral separation. The underlying cause of the event was found to be an unrectified recurrent intermittent fault in one of the Cessna’s air data systems. Poor Cessna crew/controller communication during the event, systemically poor safety culture at its operator, and shortcomings in the Textron Aircraft Maintenance Manual were considered contributory.
On 19 August 2012, the crew of a Flybe Finland ATR 72-200 approaching Helsinki failed to respond appropriately to a fault which limited rudder travel and were then unable to maintain directional control after touchdown with a veer off the runway then following. It was concluded that as well as prioritising a continued approach over properly dealing with the annunciated caution, crew technical knowledge in respect of the fault encountered had been poor and related training inadequate. Deficiencies found in relevant aircraft manufacturer operating documentation were considered to have been a significant factor and Safety Recommendations were made accordingly.
On 12 March 2009, a Sikorsky S-92A crew heading offshore from St. John's, Newfoundland declared an emergency and began a return after total loss of main gear box oil pressure but lost control during an attempted ditching. The Investigation found that all oil had been lost after two main gear box securing bolts had sheared. It was noted that ambiguity had contributed to crew misdiagnosis the cause and that the ditching had been mishandled. Sea States beyond the capability of Emergency Flotation Systems and the limited usefulness of personal Supplemental Breathing Systems in cold water were identified as Safety Issues.
On 21 November 2006, the crew of a Bristow Eurocopter AS332 L2 making an unscheduled passenger flight from an offshore platform to Den Helder in night VMC decided to ditch their aircraft after apparent malfunction of an engine and the flight controls were perceived as rendering it unable to safely complete the flight. All 17 occupants survived but the evacuation was disorganised and both oversight of the operation by and the actions of the crew were considered to have been inappropriate in various respects. Despite extensive investigation, no technical fault which would have rendered it unflyable could be confirmed.
On 5 March 2011, a Finnair Airbus A320 was westbound in the cruise in southern Swedish airspace after despatch with Engine 1 bleed air system inoperative when the Engine 2 bleed air system failed and an emergency descent was necessary. The Investigation found that the Engine 2 system had shut down due to overheating and that access to proactive and reactive procedures related to operations with only a single bleed air system available were deficient. The crew failure to make use of APU air to help sustain cabin pressurisation during flight completion was noted.
OEM Design fault
On 8 February 2022, a Boeing 767-300ER inbound to Madrid at FL340 experienced a failure of automatic pressurisation control followed almost three hours later by a failure of manual control and rapidly rising cabin altitude. An emergency was declared and descent made to FL120 where manual control was regained. The flight was completed without recurrence. The failure cause was found to have been water leaking from a tube with a broken clamp which, when it froze, had blocked the air conditioning outflow valve doors. Elements of the system design, scheduled maintenance requirements and fault detection were identified as contributing factors.
On 8 April 2022, an Airbus A320 made a multiple bounce touchdown at Copenhagen followed by thrust reverser deployment. The Captain rejected the landing and began a go-around but as the left main gear had bounced and was not on the ground when thrust was set, the left engine reverser did not stow. Full aircraft control was briefly lost and a runway excursion narrowly avoided before a recovery to a single engine MAYDAY circuit and landing followed. Engine software design prevented thrust reverser stowage without weight on wheels which was why rejected landings after reverser deployment were prohibited.
On 31 October 2021, a ‘Fuel Imbalance’ message occurred on a Boeing 787-9 soon after departing Bangkok at night but attempted fuel transfer was unsuccessful. A ‘Fuel Disagree’ message subsequently appeared and use of available system checklists indicated that there was a fuel leak from the left engine or tank. Left engine shutdown was therefore accomplished and a MAYDAY diversion to an overweight landing at Goa followed. The Investigation determined that the leak was actually from the right side fuel tank and attributed crew misdiagnosis to limited fuel system malfunction checklists and gaps in crew guidance and training on fault diagnosis.
On 22 March 2021, the pilots of a Boeing 747-8F which had just reached its initial cruise level after departing Dubai observed smoke and sparks coming from the window heating system and declared a PAN advising their intention to dump fuel and return to Dubai. With the faulty system switched off, this was accomplished without further event. It was found that the cause of the system malfunction was a design-related vulnerability with a history of recurrence which had not been adequately addressed by the aircraft manufacturer and the FAA as safety regulator following relevant NTSB Safety Recommendations made in 2007.
On 18 October 2019, a Boeing 787-9 descending to 4,500 feet to join the ILS for runway 25R at Hong Kong at 15 nm from touchdown failed to establish on the localiser. The autopilot was disconnected and the aircraft manually positioned onto the localiser from the north, establishing at 12 nm with terrain proximity not sufficient to activate the EGPWS. It was found that the deviation was attributable to an anomaly in the aircraft type Autopilot Flight Director System, and a corresponding Alert Service Bulletin was issued by Boeing to replace the faulty system component.
Damage Tolerance
On 9 February 2023, a Boeing 777-200ER was en-route near Marseille when the cabin crew observed smoke coming from a rear galley oven which was spreading into the rear passenger cabin. After an immediate initial response and use of multiple Halon Fire extinguishers, the smoke ceased after about 20 minutes but the fumes remained. Although this meant no ongoing emergency existed, some cabin crew and passengers had experienced breathing difficulties and it was decided to return to Amsterdam. The cabin crew response to the situation was subsequently assessed as contrary to applicable procedures and relevant cabin crew training seemingly inadequate.
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 12 July 2013 an unoccupied and unpowered Boeing 787-8, remotely parked at London Heathrow after an arrival earlier the same day caught fire. An investigation found that the source of the fire was an uncontained thermal runaway in the lithium-metal battery within an Emergency Locator Transmitter (ELT). Fifteen Safety Recommendations, all but one to the FAA, were made as a result of the Investigation.
On 7 January 2013, a battery fire on a Japan Air Lines Boeing 787-8 began almost immediately after passengers and crew had left the aircraft after its arrival at Boston on a scheduled passenger flight from Tokyo Narita. The primary structure of the aircraft was undamaged. Investigation found that an internal short circuit within a cell of the APU lithium-ion battery had led to uncontained thermal runaway in the battery leading to the release of smoke and fire. The origin of the malfunction was attributed to system design deficiency and the failure of the type certification process to detect this.
On 26 September 2011, a Boeing 757-200 being operated by United Airlines on a scheduled passenger flight from Chicago to Denver experienced a left engine bird strike during deceleration after landing on runway 35R at destination in normal day visibility. The affected engine ran down as the aircraft cleared the runway and was shut down after a report of smoke being emitted from it. The aircraft was stopped and the remaining engine also shut down prior to a tow to the assigned terminal gate for passenger disembarkation. None of the 185 occupants were injured but the affected engine was severely damaged and there was visible evidence that some debris from it had impacted the aircraft fuselage.
Contributing ADD
On 5 March 2011, a Finnair Airbus A320 was westbound in the cruise in southern Swedish airspace after despatch with Engine 1 bleed air system inoperative when the Engine 2 bleed air system failed and an emergency descent was necessary. The Investigation found that the Engine 2 system had shut down due to overheating and that access to proactive and reactive procedures related to operations with only a single bleed air system available were deficient. The crew failure to make use of APU air to help sustain cabin pressurisation during flight completion was noted.
On 12 October 2018, the crew of a Boeing 737-400 already released to service under MEL conditions with an inoperative No 1 engine generator encountered a loss of services from the No 2 electrical system en-route to East Midlands which created a situation not addressed by QRH procedures. The flight was completed and both the new and existing defects were subsequently rectified relatively easily. The Investigation concluded that the operator involved appeared to be prioritising operational requirements over aircraft serviceability issues and made a range of Safety Recommendations aimed at improving company safety culture and the effectiveness of regulatory oversight.
On 29 April 2017, a Boeing 787-9 which had just reached cruise altitude after despatch with only one main ECS available began to lose cabin pressure. A precautionary descent and PAN was upgraded to a rapid descent and MAYDAY as cabin altitude rose above 10,000 feet. The Investigation found that aircraft release to service had not been preceded by a thorough enough validation of the likely reliability of the remaining ECS system. The inaudibility of the automated announcement accompanying the cabin oxygen mask drop and ongoing issues with the quality of CVR readout from 787 crash-protected recorders was also highlighted.
On 5 January 2014, an Airbus A380-800 en route to Singapore at night made an emergency descent and diversion to Baku after a loss of cabin pressure without further event. The Investigation attributed the pressure loss to a fatigue crack in a door skin which was initiated due to a design issue with door Cover Plates, which had not been detected when the Cover Plate was replaced with an improved one eighteen months earlier. Safety Issues related to cabin crew use of emergency oxygen and diversions to aerodromes with a fire category less than that normally required were also identified.
On 5 June 2015, a DHC8-200 descending towards Bradley experienced an in-flight fire which originated at a windshield terminal block. Attempts to extinguish the fire were unsuccessful with the electrical power still selected to the circuit. However, the fire eventually stopped and only smoke remained. An emergency evacuation was carried out after landing. The Investigation was unable to establish the way in which the malfunction that caused the fire arose but noted the continuing occurrence of similar events on the aircraft type and five Safety Recommendations were made to Bombardier to address the continuing risk.
Component Fault in Service
On 16 September 2019, an ATR 72-200 diverted to Itaituba when landing at its intended destination Manaus was prevented by its unexpected closure due to an aircraft accident. During this diversion, intermittent indications of low fuel quantity were annunciated and one engine subsequently ran down on final approach and the other whilst backtracking after landing. It was found that due to a series of undetected faults in the aircraft’s fuel quantity sensing system, the flight deck indications of fuel tank contents were over reading and the low fuel indication system was also malfunctioning for the same reason.
On 9 February 2023, a Boeing 777-200ER was en-route near Marseille when the cabin crew observed smoke coming from a rear galley oven which was spreading into the rear passenger cabin. After an immediate initial response and use of multiple Halon Fire extinguishers, the smoke ceased after about 20 minutes but the fumes remained. Although this meant no ongoing emergency existed, some cabin crew and passengers had experienced breathing difficulties and it was decided to return to Amsterdam. The cabin crew response to the situation was subsequently assessed as contrary to applicable procedures and relevant cabin crew training seemingly inadequate.
On 6 April 2022, a Boeing 767-300 lost left engine oil pressure whilst eastbound and passing south of Cork and diverted to Shannon after declaring an emergency on account of intended engine shutdown. During the subsequent taxi in, a fire was observed and extinguished and the aircraft towed to the terminal after an initial fire service request for evacuation had been withdrawn. An engine oil leak from a chip detector which had been routinely inspected by a company engineer prior to departure but not reinstalled correctly was found to have caused the leak and thus the loss of oil pressure.
On 4 October 2023, an Airbus A321 climbing out of London Stansted with the eighteen occupants all seated towards the front of the passenger cabin was discovered to have several missing or damaged windowpanes on the left side towards the rear. The aircraft returned to land where damage was also found to one of the horizontal stabilisers. The window panes fell out because of damage by infrared energy emitted from high-intensity lights during a filming event the previous day. Four previous similar events were identified but it was found that knowledge of them was not widespread in the aviation community.
On 8 June 2016, a Boeing 737-800 en-route to Seville had already reverted to alternate automatic pressurisation control when this also failed. Manual system control was attempted but was unsuccessful so an emergency descent followed by diversion to Toulouse was then completed without further event. A similar pressurisation control fault had occurred earlier that day but had not been properly dealt with by an appropriately qualified engineer. Both system controllers were showing faults and were replaced as were a ruptured flexible hose and a series of malfunctioning drain valves. More reliable controllers and routine checking of system performance were recommended.
Component Fault After Installation
On 5 January 2024, a Boeing 737-9 which had just departed Portland was climbing through 14,800 feet when there was a loud bang followed by a rapid decompression. The cause - the loss of a fuselage plug fitted at an unused door location - was immediately obvious. An emergency was declared and a landing back at Portland was made after a total of twenty minutes airborne. The Investigation is continuing but has found that the fuselage plug involved was installed without being properly secured and noted that the aircraft had only recently been delivered new to the operator.
On 20 July 2021, a Boeing 747-8F experienced a series of problems with excessive engine speed and fire affecting the left outboard engine soon after takeoff from Hong Kong. Although the engine was shut down, the fire continued until just before landing. About twenty minutes after landing, trapped residual leaked fuel then auto-ignited, and that fire was quickly extinguished. The origin of the engine malfunction and continuing airborne fire was identified as improper installation of a component in the engine’s Fuel Metering Unit at build, which caused a fuel leak that was the sole origin of the engine malfunction.
On 31 December 2020, an Airbus A330-200 identified a fuel leak during a routine top-of-climb check but instead of following the prescribed engine shutdown and leak isolation procedure and then landing as soon as possible, the crew had continued on track until diverting to N’Djaména over 90 minutes later by which time nearly six tonnes of fuel was missing. The leak was caused by an incorrectly assembled connection at the pylon/engine interface. The flight crew’s procedural non-compliance was identified as having introduced an avoidable fire risk and been indicative of a systemically weak safety culture at the airline concerned.
On 1 March 2019, an Airbus A320 left engine suffered a contained failure soon after takeoff thrust was set for a night departure from London Stansted but despite the absence of an instruction to cabin crew to begin an evacuation, they did so anyway just before the aircraft was going to be taxied clear of the runway with the Captain only aware when passengers were seen outside the aircraft. The Investigation found that an evacuation had been ordered by the senior member of the cabin crew after she was “overwhelmed” by the situation and believed her team members were “scared”.
On 25 March 2008, an Air Atlanta Icelandic Boeing 747-300 was decelerating after landing at Dhaka when a fuel leak in the vicinity of the No 3 engine led to a fire which could not be extinguished. An emergency evacuation was accomplished with only a few minor injuries. The cause of the fuel leak was traced to mis-assembly of a fuel feed line coupling during a C Check some six months previously. The failure to follow clear AMM instructions for this task in two specific respects was of concern to the Investigating Agency.
Pilot Verbal-only Defect Communication
On 27 July 2019, a fuel configuration advisory was annunciated on a Boeing 767-300 about to depart Auckland as a result of wing tank imbalance. Having established there was no evidence of a fuel leak, they planned to correct the imbalance in flight but then delayed this until it had exceeded the permitted limits. The fault was only verbally reported after flight and the aircraft continued to operate without centre tank use with maintenance remaining unaware of the fault for several days. The cause of imbalance was a fuel system fault subject to a crew response which was not followed.
Shortly after take-off from Jersey Airport, Channel Islands, a F27 experienced an uncontained engine failure and a major fire external to the engine nacelle. The fire was extinguished and the aircraft landed uneventfully back at Jersey.
On September 13 2008, at night and in good visual conditions*, a Boeing 737-500 operated by Aeroflot-Nord executed an unstabilised approach to Runway 21 at Bolshoye Savino Airport (Perm) which subsequently resulted in loss of control and terrain impact.
On 28 November 2004, a KLM B737-400 departed laterally from the runway on landing at Barcelona due to the effects on the nosewheel steering of a bird strike which had occured as the aircraft took off from Amsterdam.
On 12 January 2009, the flight crew of an Easyjet Boeing 737-700 on an airworthiness function flight out of Southend lost control of the aircraft during a planned system test. Controlled flight was only regained after an altitude loss of over 9000 ft, during which various exceedences of the AFM Flight Envelope occurred. The subsequent investigation found that the Aircraft Operators procedures for such flights were systemically flawed.
Corrosion/Disbonding/Fatigue
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 7 April 2022, a Boeing 757-200F returning to San Jose after a left side hydraulics failure and MAYDAY declaration suddenly veered off the right hand side of the landing runway there during deceleration and passage over uneven ground led to landing gear collapse and significant fuselage structural damage. This runway excursion immediately followed simultaneous advancement of both thrust levers after their prior asymmetric movement earlier in the landing roll and resulted in high left thrust concurrent with idle thrust on the right. With no airworthiness aspect identified, the excursion was attributed to unintended thrust lever selection by the crew.
On 10 August 2019, the left Rolls Royce Trent 1000 engine of a Boeing 787-8 just airborne from Rome Fiumicino suddenly malfunctioned and was shut down. A MAYDAY was declared, and the flight returned for an overweight landing during which all four left main gear tyres deflated. The underlying cause of the engine failure was found to have been intermediate-pressure turbine blade detachment attributable to previously identified serviceability issues. Wider concerns were identified in relation to underlying engine certification standards and to the hazard created by ejection of large quantities of engine debris into a densely populated area.
On 29 September 2019, an Airbus A330-200 received simultaneous indications of low pressure in two hydraulic systems soon after takeoff. An emergency was declared, and a return to land was followed by a stop on the runway due to a burst main wheel tyre. A manual valve for one of the hydraulic systems located in the left main gear wheel well had completely detached and impact-damaged a pipe in a nearby but separate hydraulic system. Both systems lost their fluid with valve detachment attributed to fatigue failure of the attachment screws, a risk addressed by an un-adopted non-mandatory Service Bulletin.
On 16 March 2020, a PW150A-powered Bombardier DHC8-400 crew declared a PAN and turned back to Port Moresby after abnormal fumes and (much later) some visible ‘smoke’ which had become apparent after takeoff began to intensify causing some passengers breathing difficulties. Once clear of the landing runway, a precautionary rapid disembarkation was completed. The Investigation found that the source of the smoke/fumes was oil leaking from a failed right engine bearing seal. The failure was found to have occurred ahead of the recommended inspection interval for the seal concerned, a risk which engine manufacturer Pratt & Whitney Canada was aware of.
Cross Connection
On 17 October 2019, a Saab 2000 overran the Unalaska runway after touchdown following difficulty braking and exited the airport perimeter before finally coming to rest on shoreline rocks. The Investigation attributed the poor braking to incorrect brake system wiring originating during maintenance some 2½ years earlier but noted the touchdown occurred with crew awareness that the prevailing tailwind component was well in excess of the permitted limits with no reason not to use the into-wind runway and attributed this to plan continuation bias. The aircraft operator’s failure to apply their specifically-applicable airport qualification requirements to the Captain was noted.
On 11 November 2018, an Embraer 190-100LR just airborne on a post maintenance non revenue positioning flight became extremely difficult to control as it entered cloud despite the complete absence of any flight control warnings. After reversion to Direct Law, partial normal control was regained and, once visual, the flight was guided to an eventually successful landing. The Investigation found that the aircraft had been released from heavy maintenance with the aileron system incorrectly configured and attributed this primarily to the comprehensively dysfunctional working processes at the maintenance facility involved. Extensive airframe deformation meant the aircraft was a hull loss.
On 13 August 2012, an Ilyushin IL76 freighter overran landing runway 11 at St John's at 40 knots. The Investigation established that although a stabilised approach had been flown, the aircraft had been allowed to float in the presence of a significant tail wind component and had not finally touched down until half way along the 2590 metre long runway. It was also found that reverse thrust had then not been fully utilised and that cross connection of the brake lines had meant that the anti skid pressure release system worked in reverse sense, thus reducing braking effectiveness.
On 21 March 2001 an Airbus A320-200, operated by Lufthansa, experienced a flight controls malfunctions shortly after take-off which resulted in loss of control and subsequent near terrain impact. The uncontrolled roll, due to the malfunction of the pilot flying's sidestick, was recovered by the other pilot and the aircraft safely returned to land in Frankfurt without further incident.
Engine Compressor Washing
On 28 February 2019, an Embraer E195 abandoned takeoff from Exeter when fight deck fumes/smoke accompanied thrust applied against the brakes. When informed of similar conditions in the cabin, the Captain ordered an emergency evacuation. Some passengers using the overwing exits re-entered the cabin after becoming confused as to how to leave the wing. The Investigation attributed the fumes to an incorrectly-performed engine compressor wash arising in a context of poorly-managed maintenance and concluded that guidance on overwing exit use had been inadequate and that the 1.8 metre certification height limit for exits without evacuation slides should be reduced.
On 3 October 2015, an Airbus A320 which had just taken off from Dublin experienced fumes from the air conditioning system in both flight deck and cabin. A 'PAN' was declared and the aircraft returned with both pilots making precautionary use of their oxygen masks. The Investigation found that routine engine pressure washes carried out prior to departure have been incorrectly performed and a contaminant was introduced into the bleed air supply to the air conditioning system as a result. The context for the error was found to be the absence of any engine wash procedure training for the Operator's engineers.
On 9 September 2012, the crew of a DHC8-300 climbing out of Abu Dhabi declared a PAN and returned after visual evidence of the right engine overheating were seen from the passenger cabin. The Investigation found that the observed signs of engine distress were due to hot gas exiting through the cavity left by non-replacement of one of the two sets of igniters on the engine after a pressure wash carried out overnight prior to the flight and that the left engine was similarly affected. The context for the error was identified as a dysfunctional maintenance organisation at the Operator.
On 5 July 2006, during daytime, a Boeing 737-500, operated by Air Nippon Co., Ltd. took off from Fukuoka Airport as All Nippon Airways scheduled flight 2142. At about 08:10, while flying at 37,000 ft approximately 60 nm southeast of Kushimoto VORTAC, a cabin depressurization warning was displayed and the oxygen masks in the cabin were automatically deployed. The aircraft made an emergency descent and, at 09:09, landed on Chubu International Airport.
Ejected Engine Failure Debris
On 20 February 2021, a Boeing 777-200 climbing through 12,500 feet experienced a sudden right engine failure and fire shortly after thrust had been increased before entering airspace where moderate turbulence was expected. Despite actioning the corresponding drills, the fire did not go out until shortly before landing back at Denver. Engine debris fell to the ground over a wide area, fortuitously with only damage and no injuries. The failure was found to have been initiated by the fatigue failure of a single fan blade after required routine inspections had failed to find early-stage evidence of such a risk.
On 10 August 2019, the left Rolls Royce Trent 1000 engine of a Boeing 787-8 just airborne from Rome Fiumicino suddenly malfunctioned and was shut down. A MAYDAY was declared, and the flight returned for an overweight landing during which all four left main gear tyres deflated. The underlying cause of the engine failure was found to have been intermediate-pressure turbine blade detachment attributable to previously identified serviceability issues. Wider concerns were identified in relation to underlying engine certification standards and to the hazard created by ejection of large quantities of engine debris into a densely populated area.
On 20 February 2021, a Boeing 747-400BCF engine catastrophically failed as it passed 800 feet agl after takeoff from Maastricht and an uneventful diversion to Liege followed. It was subsequently found that debris ejected from the failed engine had resulted in injury to persons and property damage on the ground. Engine failure was attributed to a previous operator of the aircraft’s failure to incorporate an optional Service Bulletin during routine maintenance and the absence of a review of this decision by the current operator. The absence of any risk assessment for third parties below a regular flight path was noted.
On 20 February 2021, a PW4077-powered Boeing 777-200 was climbing through 12,500 feet after takeoff from Denver when there was a sudden uncontained failure of the right engine. The associated fire did not fully extinguish in response to the prescribed non-normal procedure and on completion of a return to land, it was fully extinguished before the aircraft could be towed in for passenger disembarkation. The Investigation has already established that the failure originated in a single fan blade within which internal fatigue cracking had been initiated. All operators of 777s powered by PW4000 series engines have grounded their fleets indefinitely.
On 11 November 2019, one of the two PW100 series engines of a Bombardier DHC8-300 failed catastrophically when takeoff power was set prior to brake release. The Investigation found that the power turbine shaft had fractured in two places and all first and second stage power turbine blades had separated from their disks. The shaft failure was found to have been caused by fatigue cracking initiated by corrosion pitting which was assessed as probably the result of prolonged marine low-altitude operations by the aircraft. It was found that this fatigue cracking could increase undetected during service between scheduled inspections.
Dispatch of Unserviceable Aircraft
On 8 June 2016, a Boeing 737-800 en-route to Seville had already reverted to alternate automatic pressurisation control when this also failed. Manual system control was attempted but was unsuccessful so an emergency descent followed by diversion to Toulouse was then completed without further event. A similar pressurisation control fault had occurred earlier that day but had not been properly dealt with by an appropriately qualified engineer. Both system controllers were showing faults and were replaced as were a ruptured flexible hose and a series of malfunctioning drain valves. More reliable controllers and routine checking of system performance were recommended.
On 26 February 2020, after a difficult Airbus A321 left engine first flight of the day start, the same happened on the third sector with en-route engine abnormalities then affecting both engines. With no fault found during post flight maintenance inspections and despite similar engine starting problems, both engines then malfunctioned after takeoff from Gatwick. A MAYDAY return followed. Investigation found that the cause was fuel system contamination by addition of approximately 38 times the correct quantity of biocide during earlier scheduled maintenance and that the release of the aircraft to service for the flight had followed inadequate troubleshooting action.
On 13 April 2013, an Air France Airbus A330-200 was damaged during a hard (2.74 G) landing at Caracas after the aircraft commander continued despite the aircraft becoming unstabilised below 500 feet agl with an EGPWS ‘SINK RATE’ activation beginning in the flare. Following a superficial inspection, maintenance personnel determined that no action was required and released the aircraft to service. After take off, it was impossible to retract the landing gear and the aircraft returned. Considerable damage from the earlier landing was then found to both fuselage and landing gear which had rendered the aircraft unfit to fly.
On 27 February 2001, a Loganair SD3-60 lost all power on both engines soon after take off from Edinburgh. An attempt to ditch in the Firth or Forth in rough seas resulted in the break up and sinking of the aircraft and neither pilot survived. The loss of power was attributed to the release of previously accumulated frozen deposits into the engine core when the engine anti icing systems were selected on whilst climbing through 2200 feet. These frozen deposits were considered to have accumulated whilst the aircraft had been parked prior to flight without engine intake blanks fitted.
On 12 October 2018, the crew of a Boeing 737-400 already released to service under MEL conditions with an inoperative No 1 engine generator encountered a loss of services from the No 2 electrical system en-route to East Midlands which created a situation not addressed by QRH procedures. The flight was completed and both the new and existing defects were subsequently rectified relatively easily. The Investigation concluded that the operator involved appeared to be prioritising operational requirements over aircraft serviceability issues and made a range of Safety Recommendations aimed at improving company safety culture and the effectiveness of regulatory oversight.
Maintenance FOD
On 22 September 2021, a Boeing 787-9 was found on arrival at its destination, Los Angeles, to have completed the 14½ hour flight from Melbourne with all four fan cowl static ports taped over. The crew had not observed any adverse consequence. The Investigation attributed the oversight to inadequate pre-flight maintenance and operational procedures and found that failure to identify the taping had resulted in the aircraft departing with reduced redundancy to the engine electronic control systems of both engines.
On 23 October 2020, an Airbus A320 taking off from Brisbane became difficult to keep on the centreline as speed increased and takeoff was rejected from a low speed. It remained on the runway and messages indicating a malfunctioning right engine were then seen. The Investigation found that one engine had surged as thrust was applied due to damage caused by a screwdriver tip inadvertently left in the engine during routine maintenance and that the pilot flying had used the rudder when attempting to maintain directional control during the reject despite its known ineffectiveness for this purpose at low speeds.
On 7 December 2016, the crew of an ATR 42-500 lost control after airworthiness-related complications followed shutdown of the left engine whilst in the cruise and high speed terrain impact followed. The Investigation concluded that three pre-existing faults with the left engine and its propeller control mechanism had led to a loss of power which had necessitated its shutdown but that these faults had then caused much higher left side drag than would normally result from an engine shutdown and made it progressively more difficult to maintain control. Recovery from a first loss of control was followed by another without recovery.
On 27 October 2017, an Airbus A320 returned to Auckland after advice from ATC that the right engine may have been affected by ingestion of FOD during engine start - a clipboard and paper left just inside the right hand engine by an employee of the airline’s ground handling contractor acting as the aircraft loading supervisor. The subsequent inspection found paper throughout the engine and minor damage to an engine fan blade and the fan case attrition liner. The Dispatcher overseeing the departure said she had seen the clipboard inside the engine but assumed it would be retrieved before departure.
On 11 February 2017, a Cessna 402 failed to stop on the runway when landing at Virgin Gorda and was extensively damaged. The Investigation noted that the landing distance required was very close to that available with no safety margin so that although touchdown was normal, when the brakes failed to function properly, there was no possibility of safely rejecting the landing or stopping normally on the runway. Debris in the brake fluid was identified as causing brake system failure. The context was considered as the Operator s inadequate maintenance practices and a likely similar deficiency in operational procedures and processes.
In flight separation of failed component
On 4 October 2023, an Airbus A321 climbing out of London Stansted with the eighteen occupants all seated towards the front of the passenger cabin was discovered to have several missing or damaged windowpanes on the left side towards the rear. The aircraft returned to land where damage was also found to one of the horizontal stabilisers. The window panes fell out because of damage by infrared energy emitted from high-intensity lights during a filming event the previous day. Four previous similar events were identified but it was found that knowledge of them was not widespread in the aviation community.
On 5 January 2024, a Boeing 737-9 which had just departed Portland was climbing through 14,800 feet when there was a loud bang followed by a rapid decompression. The cause - the loss of a fuselage plug fitted at an unused door location - was immediately obvious. An emergency was declared and a landing back at Portland was made after a total of twenty minutes airborne. The Investigation is continuing but has found that the fuselage plug involved was installed without being properly secured and noted that the aircraft had only recently been delivered new to the operator.
On 8 July 2019, a loud bang was heard following intermediate flap selection on a Boeing 747-400F making an approach to Harare and a concurrent uncommanded right roll was countered with left aileron. The flight was completed without further event but a post-flight inspection found part of the inboard section of the right wing flap assembly was missing and the right fuselage impact-damaged in several places. The missing flap section measuring 3.7 metres by 0.6 metres was recovered with detachment attributed to undetected fatigue cracking already present at component installation. A long history of problems with 747 flaps was noted.
On 1 August 2019, an Airbus A320 annunciated an abnormal gear status indication when retraction was attempted after takeoff. Soon afterwards, an aircraft part was observed by an aircraft following the same taxi route as the A320 and recovered. After completing relevant drills, the A320 returned and completed a landing with significant damage to the left main gear which was nevertheless locked down. The runway was vacated and passengers disembarked. The Investigation found that the cause of the problem was the cyclic fatigue of a pin linking the two parts of the left main gear torque link of manufacturing origin.
On 25 March 2018, an ATR 42-500 main landing gear bay door weighing 15 kg detached shortly after a night descent had begun but this was unknown until the flight arrived at Aurillac. The Investigation found that the root cause of the detachment was a loose securing nut which had triggered a sequence of secondary failures within a single flight which culminated in the release of the door. It was concluded that the event highlighted specific and systemic weakness in relevant airworthiness documentation and practice in relation to the lost door and the use of fasteners on this aircraft type generally.
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