Emergency Evacuation is the urgent abandonment of an aircraft utilising all useable exits.
Evacuation in progress from A310 which crash landed, 12 July 2000 - copyright Vienna Airport Press Department
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, an 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.
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:
On 27 January 2020, an MD83 made an unstabilised tailwind non-precision approach to Mahshahr with a consistently excessive rate of descent and corresponding EGPWS Warnings followed by a very late nose-gear-first touchdown. It then overran the runway end, continued through the airport perimeter fence and crossed over a ditch before coming to a stop partly blocking a busy main road. The aircraft sustained substantial damage and was subsequently declared a hull loss but all occupants completed an emergency evacuation uninjured. The accident was attributed entirely to the actions of the Captain which included disregarding multiple standard operating procedures.
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.
On 8 February 2021, an Embraer 500 Phenom 100 (9H-FAM) crew lost control of their aircraft shortly before the intended touchdown when it stalled due to airframe ice contamination. The resulting runway impact collapsed the nose and main gear, the latter causing fuel leak and resultant fire as the aircraft slid along the runway before veering off it. The Investigation found that flight in icing conditions during the approach had not been accompanied by the prescribed use of the airframe de-icing system and that such non compliance appeared to be routine and its dangers unappreciated.
On 2 October 2021, an Airbus A320neo ingested a large bird into its right engine (a Pratt & Whitney PW1100G) during takeoff at Atlantic City and a high speed rejected takeoff followed. When leaked fuel pooling within the engine cowling subsequently ignited, an on-runway emergency evacuation was completed with the fire service in attendance. The Investigation identified the ingested bird as a bald eagle with a mass above the applicable certification standard and the fuel leak a secondary consequence of a fan blade broken by bird impact. Engine component design improvements to address the fire risk following large bird ingestion are being developed.
On 6 December 2018, a Boeing 737-700 overran the 1,770 metre-long landing runway at destination by 45 metres after entering the EMAS. Normal visibility prevailed but heavy rain was falling and a 10 knot tailwind component existed. The event was attributed to the pilots’ continuation bias in the face of deteriorating conditions and a late touchdown on the relatively short runway. A lack of guidance from the operator on the need for pilots to re-assess the validity of landing data routinely obtained at the top of descent was identified.