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  • B733, vicinity Helsinki Finland, 2008 (Synopsis: On 26 March 2008, a Ukraine International Airlines’ Boeing 737-300 being vectored by ATC to the ILS at destination Helsinki in IMC descended below its cleared altitude and came close to a telecommunications mast. ATC noticed the deviation and instructed a climb. The investigation attributed the non-compliance with the accepted descent clearance to the failure of the flight crew to operate in accordance with SOPs. It was also noted that the way in which ATC safety systems were installed and configured at the time of the occurrence had precluded earlier ATC awareness of the hazard caused by the altitude deviation.)
  • A310 / B736, en-route, Southern Norway, 2001 (Synopsis: On 21 February 2001, a level bust 10 nm north of Oslo Airport by a climbing PIA A310 led to loss of separation with an SAS B736 in which response to a TCAS RA by the A310 not being in accordance with its likely activation (descend). The B736 received and correctly actioned a Climb RA.)
  • A346, en route, eastern Indian Ocean, 2013 (Synopsis: On 3 February 2013, an Airbus A340 crew in the cruise in equatorial latitudes at FL350 in IMC failed to use their weather radar properly and entered an area of ice crystal icing outside the prevailing icing envelope. A short period of unreliable airspeed indications on displays dependent on the left side pitot probes followed with a brief excursion above FL350 and reversion to Alternate Law. Excessive vibration on the left engine then began and a diversion was made. The engine remained in use and was subsequently found undamaged with the fault attributed to ice/water ingress due to seal failure.)
  • B744, en-route, southeast of Hong Kong SAR China, 2017 (Synopsis: On 7 April 2017, a Boeing 747-400 crew did not adjust planned speed at an anticipated holding point when the level given was higher than expected. As a consequence of this and distraction, as the new holding level was approached and the turn began, stall buffet, several stick shaker activations and pilot-induced oscillations occurred when the crew failed to follow the applicable stall warning recovery procedure. Descent below the cleared level occurred and the upset caused injuries in the passenger cabin. Whilst attributing the event to poor crew performance, the Investigation also concluded that related operator pilot training was inadequate.)
  • GLF5 / A319, south-eastern France, 2004 (Synopsis: On 16 September 2004, a loss of separation occurred over Geneva between Air France A319 and a Gulfstream 5 which commenced descent without clearance by ATC and with coordinated TCAS RAs not followed by either aircraft.)
  • A320, en-route, north of Swansea UK, 2012 (Synopsis: On 7 September 2012, the crew of an Aer Lingus Airbus A320-200 mis-set their descent clearance. When discovering this as the actual cleared level was being approached, the AP was disconnected and the unduly abrupt control input made led to an injury to one of the cabin crew. The original error was attributed to ineffective flight deck monitoring and the inappropriate corrective control input to insufficient appreciation of the aerodynamic handling aspects of flight at high altitude. A Safety Recommendation to the Operator to review relevant aspects of its flight crew training was made.)
  • DH8D, vicinity Edinburgh UK, 2008 (Synopsis: On 23 December 2008, a DHC8-400 being operated by Flybe on a scheduled passenger flight from Southampton to Edinburgh continued descent below its cleared altitude of 2100ft in day VMC prior to and then whilst tracking the ILS LLZ for Runway 23 at destination. It remained below the ILS GS until the ATC GND Controller, who had no formal responsibility for this phase of flight but was positioned alongside the TWR Controller, observed that aircraft had descended to within 800 ft of local terrain approximately 5 nm from the runway threshold. The flight crew appeared unaware of this when making a ‘Finals’ call to TWR at 5.5 nm and so the Controller queried the descent. The aircraft was then levelled to achieve 600ft agl at 4nm from the threshold and an uneventful landing subsequently followed.)
  • C525 / B773, vicinity London City UK, 2009 (Synopsis: On 27 July 2009, a Cessna 525 departing from London City failed to comply with the initial 3000 feet QNH SID Stop altitude and at 4000 feet QNH in day VMC came into close proximity on an almost reciprocal heading with a Boeing 777-300ER. The 777, on which line training was being conducted, failed to follow any of the three TCAS RAs generated. Actual minimum separation was approximately 0.5nm laterally and estimated at between 100 feet and 200 feet vertically. It was noted that the Cessna had been given a stepped climb SID.)
  • A319/B733, en-route, near Moutiers France, 2010 (Synopsis: On 8 July 2010 an Easyjet Airbus A319 on which line training was being conducted mis-set a descent level despite correctly reading it back and, after subsequently failing to notice an ATC re-iteration of the same cleared level, continued descent to 1000 feet below it in day VMC and into conflict with crossing traffic at that level, a Boeing 737. The 737 received and actioned a TCAS RA ‘CLIMB’ and the A319, which received only a TCAS TA, was given an emergency turn by ATC. The recorded CPA was 2.2 nm and 125 feet.)
  • B734 / MD81, en-route, Romford UK, 1996 (Synopsis: On 12 November 1996, a B737-400 descended below its assigned level in one of the holding patterns at London Heathrow in day IMC to within 100 feet vertically and between 680 and 820 metres horizontally of a MD-81 at its correct level, 1000 feet below. STCA prompted ATC to intervene and the 737 climbed back to its cleared level. Neither aircraft was fitted with TCAS 2 or saw the other visually.)
  • A321 / B738, en-route, south eastern Bulgaria, 2016 (Synopsis: On 8 September 2016, an Airbus A321 en route in Bulgarian airspace at FL 350 was given and acknowledged a descent but then climbed and came within 1.2nm of a descending Boeing 737. The Investigation found that the inexperienced A321 First Officer had been temporarily alone when the instruction was given and had insufficient understanding of how to control the aircraft. It was also found that despite an STCA activation of the collision risk, the controller, influenced by a Mode ‘S’ downlink of the correctly-set A321 cleared altitude, had then added to the risk by instructing the 737 to descend.)
  • A310, vicinity Birmingham UK, 2006 (Synopsis: On 24 November 2006, an A310 descended significantly below cleared altitude during a radar vectored approach positioning, as a result of the flight crew's failure to set the QNH, which was unusually low.)
  • FA50, vicinity London City UK, 2010 (Synopsis: On 21 January 2010, a Mystere Falcon 50 being operated by TAG Aviation on a positioning flight from Biggin Hill to London City in day VMC began a descent at a high rate below its cleared altitude of 2000 ft amsl because the aircraft commander believed, on the basis of external visual cues, that the aircraft was on a final approach track for Runway 27 at destination when in fact it was downwind for Runway 09. After an alert from ATC as the aircraft passed 900 ft agl at a rate of descent of approximately 2200 fpm, recovery to a normal landing on Runway 09 was achieved.)
  • DH8D / B772, vicinity Sydney Australia, 2016 (Synopsis: On 9 December 2016, a Bombardier DHC8-400 departing Sydney lost prescribed separation against an inbound Boeing 777-200 after its crew failed to ensure that the aircraft levelled as cleared at 5,000 feet and this was exceeded by 600 feet. The Investigation found that the First Officer, as Pilot Flying, had disconnected the autopilot prior to routinely changing the selected airspeed because it tended to disconnect when this was done with altitude capture mode active but had then failed to re-engage it. The Captain's lack of effective monitoring was attributed to distraction as he sought to visually acquire the conflicting traffic.)
  • F15 / E145, en-route, Bedford UK, 2005 (Synopsis: On 27 January 2005, two USAF-operated McDonnell Douglas F15E fighter aircraft, both continued to climb and both passed through the level of an Embraer 145 being operated by British Airways Regional on a scheduled passenger flight from Birmingham to Hannover, one seen at an estimated range of 100 feet.)
  • B738, en-route, south south west of Brisbane Australia, 2013 (Synopsis: On 25 February 2013, a Boeing 737-800 about to commence descent from FL390 began to climb. By the time the crew recognised the cause and began to correct the deviation - their unintended selection of a inappropriate mode - the cleared level had been exceeded by 900 feet. During the recovery, a deviation from track occurred because the crew believed the autopilot had been re-engaged when it had not. The Investigation noted the failure to detect either error until flight path deviation occurred and attributed this to non-compliance with various operator procedures related to checking and confirmation of crew actions.)
  • B733, vicinity Manchester UK, 1997 (Synopsis: On 1 August 1997, an Air Malta B737, descending for an approach into Manchester UK in poor weather, descended significantly below the cleared and correctly acknowledged altitude, below MSA.)
  • A388, vicinity Moscow Domodedovo Russia, 2017 (Synopsis: On 10 September 2017, an Airbus A380-800 cleared for an ILS approach at Moscow Domodedovo in visual daylight conditions descended below its cleared altitude and reached 395 feet agl whilst still 7nm from the landing runway threshold with a resultant EGPWS ‘PULL UP’ warning. Recovery was followed by an inadequately prepared second approach which was discontinued and then a third approach to a landing. The Investigation attributed the crew’s difficulties primarily to failure to follow various routine operating procedures relating to use of automation but noted that there had been scope for better presentation of some of these procedures.)