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Emergency Evacuation on Land
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|Category:||Fire Smoke and Fumes|
Emergency Evacuation is the urgent abandonment of an aircraft utilising all useable exits.
Failure to evacuate the aircraft in a timely manner may lead to the death or injury of crew and passengers. Failure to evacuate an aircraft in an orderly and safe manner may also lead to injuries to passengers. This article provides an overview of the more common scenarios, certification requirements, crew response, aircraft equipment, and inherent risks of an evacuation. For a more complete treatise on the subject, refer to the Royal Aeronautical Society (RAeS) paper listed under Further Reading.
An inflight fire, smoke or fume emergency will be dealt with as aggressively as possible by the crew and, if appropriate, an immediate diversion to landing will be initiated. If the emergency is not secured, once on the ground, the most appropriate course of action is to remove the passengers and crew from the risk as a precautionary measure. Likewise, in the event of an uncontrolled engine or airframe fire during ground operations, an aircraft crash on a takeoff or landing, or any other situation that results in fire or structural failure, the best defence available is an immediate evacuation of the aircraft.
- During the takeoff roll, the number two engine fire warning system is activated. The takeoff is rejected and the aircraft is stopped on the runway. Checklist items are carried out but the warnings persist and the air traffic control tower reports smoke and flames on the right wing of the aircraft. The remaining engine is shut down and an evacuation is initiated. Rescue and Fire Fighting Services (RFFS) arrive on scene within 3 minutes and extinguish the fire. Minor injuries are reported by some passengers as a result of the evacuation
- An inflight fire in a rear toilet fills the aircraft with smoke. An emergency is declared and, after some initial evaluation during which the situation worsens, the aircraft diverts to land at a nearby airport. RFFS are on scene and evacuation is initiated immediately after the aircraft comes to a stop on landing. Flashover occurs before the evacuation is complete resulting in the deaths of many of those on board.
As part of the certification process, aircraft manufacturers are required to demonstrate that an aircraft, in maximum density configuration, can be completely evacuated within 90 seconds using only half of the total number of emergency exits. Use of only half of the exits simulates the potential for failed evacuation devices or exits blocked due to fire or structural damage. Ninety seconds has been established as the maximum evacuation time because tests have shown that, in a post crash fire, conditions conducive to flashover are unlikely to occur within that time span. However, the experience of actual evacuations, especially unexpected ones from full aircraft where the abnormal situation occurs suddenly at or soon after landing, indicates that evacuation times usually exceed durations demonstrated for certification purposes.
- Video showing the emergency evacuation test for the Airbus A380 at Hamburg
- Video showing the certification trial for the Airbus A380 at Toulouse
- Video showing the Boeing 777 emergency evacuation test
Common Evacuations Issues
Common safety deficiencies during the evacuation process are often associated with communications, exit operation, passenger preparedness for evacuations, and the presence of fire, smoke, and toxic fumes.
As much as a minute can pass before the ﬂight or cabin crew initiates the evacuation. This is a very long time for passengers to endure if it is obvious that an emergency situation exists. On the other hand, if the emergency is not obvious, passengers may revert to their routine and e.g. start opening the overhead bins to retrieve their luggage. This action will be very difficult to prevent when the cabin crewmembers are required to remain at their stations near the emergency exits.
In an emergency evacuation, effective communications among the crew members and with the passengers is essential for a timely, orderly, effective response. The communication could be hindered by
- Inoperative Public Address (PA) systems - The cabin crew and/or passengers are unable to hear the initial evacuation command and/or subsequent directions. PA systems could be rendered inoperable or unintentionally switched off during evacuations.
- Inadequate crew communication - Non-effective communication between the cabin and the flight deck could result in a significant delay of the evacuaion.
Exit and Slide Operation
Problems in operating emergency exits and deploying emergency slides delayed many evacuations, potentially compromising the success of the evacuation. Cabin crew or passengers could experience difficulty operating emergency exit doors.
Passengers' lack of preparedness to act appropriately, or adverse behaviour, during an evacuation is a serious issue during many evacuations. Passengers might not perceive the danger they are in and therefore could act in an inappropriate manner (e.g. being slow to respond to cabin crew instructions, looking for friends and relatives or even trying to open overhead compartment storage to retrieve luggage).
Fire, Smoke and Fumes
The presence of fire, smoke, and/or toxic fumes present the greatest risk to a successful evacuation by restricting visibility, limiting communications, reducing the number of available exits, affecting passenger behaviour, and decreasing occupants' mental and physical capacities. Fire, smoke, and/or toxic fumes are identified as a serious hazard during the evacuations.
For example, in the B732, Manchester UK, 1985 accident, the major cause of the fatalities was rapid incapacitation due to the inhalation of the dense toxic/irritant smoke atmosphere within the cabin.
As part of their pre-departure duties, the Cabin Crew will provide a Safety Briefing to passengers which will include the emergency evacuation of the aircraft. This briefing will refer passengers to their individual Safety Briefing Cards but will always include pointing out exit locations and floor path lighting for particular use in poor visibility. The briefing will advise on the availability of evacuation slides at exits and may give instructions on how to open exits. Passengers seated in emergency exit rows at overwing exits where no cabin crew are located may be individually briefed on how to open these in the event of an emergency. If an airborne emergency occurs which makes an evacuation on landing likely, then the Cabin Crew will provide more detailed instructions if the time available permits.
The results of evacuation trials have shown that the opening of emergency doors by passengers was proven to be more successful when the passengers were familiarized with the instructions provided in the safety cards, or when a personal briefing was provided by a cabin crewmember.
Depending upon the aircraft, emergency exits can include normal boarding and service doors, overwing exits, and tailcone exits within the passenger cabin; and cockpit windows or hatches on the flight deck and in freight bays. These may be equipped with boarding stairs, evacuation slides or emergency egress ropes. For a more complete description of exit types, refer to section 7.2 of the Royal Aeronautical Society (RAeS) paper Emergency Evacuation of Commercial Passenger Aeroplanes.
An evacuation slide is an inflatable device which facilitates the rapid evacuation of an aircraft. Slides are required on all passenger carrying aircraft where the door sill height (measured as the normal height above ground level) is such that able bodied passengers would be unable to jump or "step down" from the exit without a significant risk of injury. This has been interpreted in Regulatory requirements as meaning slides must be installed at all aircraft doors where the floor is 1.8 metres (6 feet) or more above the ground. Slides are also required on overwing exits when the height of the wing above the ground, with the flaps fully extended, exceeds the maximum certified distance or where an evacuation route ahead of the wing is intended. Some slides are also designed to serve as rafts when detached from the aircraft in the event of a landing on water.
In the case of over-wing exits, no slide is required providing the escape route utilises the flap surface and the height to the ground from the trailing edge of the flap is less than six feet.
Cabin Crew Duties
Evacuation is normally ordered by the Captain. However, if communication with the flight crew is not possible and the situation in the cabin is judged by the senior cabin crew member to be incompatible with any delay, then they are trained to make the evacuation order themselves once the aircraft has come to a complete stop. In these circumstances, they are responsible for assessing immediate danger such as external fire or engines still running before any exit is opened. Cabin crew supervising exits must also secure the exit until the slide (if the exit is so equipped) inflates and block the exit from use in the event of a slide malfunction. They are also expected to motivate passengers using appropriate shouted commands and if necessary, physical action, to exit quickly and to leave behind personal possessions, especially items in overhead lockers or under seats. Normally, the Cabin Crew will be the last to leave their exit; however, in practice they are trained to remain on board only to the point when they believe that by staying any longer they are putting their own lives at risk. Once they are out of the aircraft, they are trained to assist in moving passengers away from the aircraft to a position where they can be safely grouped together.
Accidents & Incidents
The Following is a list of events which have involved emergency aircraft evacuation:
- A139, vicinity Sky Shuttle Heliport Hong Kong China, 2010 (On 3 July 2010, an AW139 helicopter was climbing through 350 feet over Victoria Harbour Hong Kong just after takeoff when the tail rotor detached. A transition to autorotation was accomplished and a controlled ditching followed. All occupants were rescued but some sustained minor injuries. The failure was attributed entirely to manufacturing defects but no corrective manufacturer or regulatory action was taken until two similar accidents had occurred in Qatar (non-fatal) and Brazil (fatal) the following year and two interim Safety Recommendations were issued from this Investigation after which a comprehensive review of the manufacturing process led to numerous changes.)
- A310, Irkutsk Russia, 2006 (On 8 July 2006, S7 Airlines A310 overran the runway on landing at Irkutsk at high speed and was destroyed after the Captain mismanaged the thrust levers whilst attempting to apply reverse only on one engine because the flight was being conducted with one reverser inoperative. The Investigation noted that the aircraft had been despatched on the accident flight with the left engine thrust reverser de-activated as permitted under the MEL but also that the previous two flights had been carried out with a deactivated right engine thrust reverser.)
- A310, Vienna Austria, 2000 (On 12 July 2000, a Hapag Lloyd Airbus A310 was unable to retract the landing gear normally after take off from Chania for Hannover. The flight was continued towards the intended destination but the selection of an en route diversion due to higher fuel burn was misjudged and useable fuel was completely exhausted just prior to an intended landing at Vienna. The aeroplane sustained significant damage as it touched down unpowered inside the aerodrome perimeter but there were no injuries to the occupants and only minor injuries to a small number of them during the subsequent emergency evacuation.)
- A319, Belfast Aldergrove UK, 2011 (On 6 January 2011 an Easyjet Airbus A319 experienced the sudden onset of thick "smoke" in the cabin as the aircraft cleared the runway after landing. The aircraft was stopped and an evacuation was carried out during which one of the 52 occupants received a minor injury. The subsequent investigation attributed the occurrence to the continued use of reverse idle thrust after clearing the runway onto a little used taxiway where the quantity of de-ice fluid residue was much greater than on the runway.)
- A319, London Heathrow UK, 2013 (On 24 May 2013 the fan cowl doors on both engines of an Airbus A319 detached as it took off from London Heathrow. Their un-latched status after a routine maintenance input had gone undetected. Extensive structural and system damage resulted and a fire which could not be extinguished until the aircraft was back on the ground began in one engine. Many previously-recorded cases of fan cowl door loss were noted but none involving such significant collateral damage. Safety Recommendations were made on aircraft type certification in general, A320-family aircraft modification, maintenance fatigue risk management and aircrew procedures and training.)
- Emergency Evacuation of Commercial Passenger Aeroplanes, Second Edition 2020, Royal Aeronautical Society (RAeS) paper published in June 2020.
- CAP 1150 - Information Paper 04 Task and Resource Analysis- establishes justification as to the minimum number of qualified/competent personnel required to deliver an effective Airport Rescue and Fire fighting Service (RFFS) to deal with an aircraft incident/accident.
- CAP 699 - Framework for the competence of rescue and fire fighting service (RFFS) personnel, January 2017
- A Safety Study of evacuations of large passenger-carrying aircraft, TSB Canada, October 2013.
- Cabin Operations Safety: Best Practices Guide 3rd Edition by IATA, 2017
- Passenger Behavior during Aircraft Evacuations, an article in the December 2017 issue of "The Investigator" magazine