Airplane fires

From a Captain’s perspective, there are challenges flying an aircraft and managing a fire but flight crew are equipped to deal with these scenarios.

In 1991, a Canadian aircraft crashed 10mins after takeoff due to an uncontrollable fire. After approximately 7 minutes, while still in the air, the aircraft began breaking up. While this, thankfully, is an extremely rare example, it highlights just how little time flight crew possibly have to resolve an aircraft fire. The option to pull over and park doesn’t always exist.

An airline flight crew will weigh many complex variables in a short space of time when it comes to managing aircraft fires. Considerations will include the type, source and severity of the fire as well as where the aircraft physically is in relation to being able to stop. Other factors like the wind direction, Air Traffic Control and any degradation of flying controls all play a part. And this is in addition to ensuring the aircraft is safely flown.

Sources of fire

Engine fires are thankfully very rare despite the fact that the typical temperature of the combustion chamber is around 2000˚C. There is an incredible amount of cooling technology that allows these temperatures to exist but it only becomes a hazard when this technology is compromised, damaged or there is a breakdown of fire stopping seals.

In the cabin, the seat cushions, floor coverings, wall coverings, window shades, acoustic insulation, wire insulation, curtains and carpeting are common combustibles but the provision of food onboard necessitates an oven. Galley oven fires contribute to a relatively high incidence of fires onboard and typically occur due to the long term buildup of food residue that ignites during heating cycles if left uncleaned.

Lithium batteries are a relatively new potential fire source and their presence has become more commonplace. Lithium batteries are frequently used due to their stability, larger energy density and temperature tolerance. While they are very stable unless damaged, the main problem with the method of dealing with a lithium battery fire, by thoroughly dowsing with water, is that there is a high chance of sensitive aircraft electronics located nearby.

Managing Smoke

Firefighting has a lot of expected challenges, such as lack of space, lack of access and lack of plentiful resources but the dissipation of smoke can be a significant challenge due to the nature of an aircraft being a pressurised and, mostly, sealed container without always being able to quickly evacuate. An aircraft in flight, though, has one advantage over a building by being able to increase the amount of air that is expelled overboard. In flight, this is done by opening the Outflow valve. This valve is normally used to control the pressurisation and opens different amounts depending on the altitude of the aircraft and how much pressurisation is required.

At altitude, if the flight crew manually open the Outflow valve, this has the effect of sending more air out and, with it, any smoke or fumes without increasing the amount of air fed in. However, if at high altitudes, this technique will result in a quick depressurisation of the aircraft as there isn’t enough air from the air conditioning packs to match the rate of expulsion and so it will be necessary to descend the aircraft, if that hasn’t already been initiated, to a lower altitude. This in itself has implications if there is high terrain or, if a long way from land, fuel considerations (more fuel is burnt at lower altitudes) but priority will be given to managing the fire as the largest threat.

There is always a balance to be struck between managing a fire and flying the aircraft safely. During the rapid descent from altitude, there still needs to be effective piloting and monitoring of the aircraft and flight path. The stress levels in the flight deck are increased in a non-normal event and so effective workload management is an important skill. Tools, such as procedures and checklists have been developed to guide crew in managing a fire and assist in managing the resultant increase in workload.

Decision Making

Any fire presents a significant risk but, for an airplane, being on the ground at an airport is a huge advantage. Not only is it easier and quicker to get help from the fire brigade but other agencies, such as air traffic control, can also be a great set of eyes outside the aircraft. Ultimately and obviously, it’s a lot easier and quicker to evacuate an aircraft on the ground. In this light, a Captain’s main priority becomes getting the aircraft on the ground as soon as possible when any fire is discovered.

Once on the ground there are two main decisions – to stay on the aircraft until able to disembark more orderly or to initiate an evacuation using the aircraft’s slides. Both are viable options. The Federal Aviation Authority (FAA) in the United States conducted a study of injuries resulting from slide evacuation of aircraft between 1996 and 2006, and identified that in this period 441 people received minor injuries and 35 received serious injuries from using slides.

A lot of the decision to evacuate will hinge around the source of fire, the spread, a fire service recommendation or the likelihood of escalation of the fire (eg. if fuel were to ignite). In the case of an engine fire, the flight crew will consider in a little more depth whether the fire is contained (either inside the fire wall casing or the tailpipe, for instance) or if it is consuming other parts of the aircraft. Anything that will likely threaten the occupants of the cabin would lend itself to a prompt evacuation.

However, even if a full evacuation wasn’t initiated, it would still be expected that all occupants would be disembarked as promptly as possible after a significant fire. It would be unusual to attempt to carry on, largely because the extinguishing agent used by the fire service can be messy and make moving an aircraft difficult but also because there might be damage that could be hazardous if the aircraft was moved. In this scenario, boarding steps would normally be used as these are a lot safer for disembarking passengers but fire service ladders have also been used in the past.

Thankfully, it is rare to be in a scenario that requires an evacuation but it is a regular good practice to rehearse what the normal actions are upon discovering a fire. They will brief, daily, the drill procedures of an evacuation alongside their normal departure briefing. In the end, evacuations using the aircraft’s slides are inherently risky operations and so a decision to evacuate is usually deliberate and considered.

Training

In the UK, the training set up in an airline requires that pilots undergo simulator checks every 6 months covering a vast array of unusual and emergency scenarios. This creates a focus on maintaining good standards for managing ‘non-normals’ but also helps increase the overall skill level of aircrew. They regularly cover events such as engine failures during or shortly after takeoff leading either to reject a takeoff or, if airborne, to managing the aircraft safely back to the ground. Oftentimes, management of a fire, smoke or fumes is introduced in one of these scenarios.

During these simulator sessions, the flight crew practice and rehearse their interaction with cabin crew, air traffic control and fire services as well as being tested on the ability to manage their procedures. Additionally, a large proportion of the assessment is centred around the non-technical or soft skills. These include skills in communication, workload management, situational awareness, knowledge of procedures, teamwork and leadership.

‘Airmanship’

Some of these skills are thoroughly developed to help improve the ‘airmanship’ side of scenario management. This is a term generally given to the application of sound common sense and adherence to good practices whether written down or not. For example, a consideration to turn the aircraft (subject to the width of the runway and the manoeuvrability of the aircraft) so that any flames, heat or smoke is on the downwind side of the aircraft and, consequently, blown away from the main body of the aircraft. This helps to reduce the chances of a breach of the passenger cabin.

Decisions like this help to buy time to allow the crew the ability to build a clearer picture of the scenario. This, in turn, would help to improve any decision made and, ultimately, save lives and reduce injuries. In the end, any unusual event carries a degree of risk and so an evacuation of the aircraft is likely a high priority in the event of a fire, especially if there becomes evidence of it in the cabin.

Checklists

Flight and cabin crew have some tools to help manage unusual and complex scenarios, including for various types of fire. I mentioned above that they practice laid down procedures (known as Standard Operating Procedures or SOPs for short) but they also call upon checklists to guide them through managing these unusual and emergency events. The checklists are written such that they can be applied at any time, whether parked at the terminal, after rejecting a takeoff or managing a problem in the air.

The main aim of the checklist is to get the aircraft condition into a more controllable and manageable state. There are many checklists but the checklists related to fire and smoke guide you through identifying the source and then taking appropriate action to isolate that source and deal with it. Checklists for emergencies operate on the ‘Read and Do’ principle where one flight crew member will read aloud the checklist and complete the relevant actions while the other pilot is flying the aircraft.

One of the most important aspects with regard to managing any event is that a Captain, only in the interests of safety, can break a rule or disregard a procedure if it doesn’t fit the scenario. As with the fire industry, policies and procedures are built based on past experience and forecast good practice but, in reality, a one size fits all policy or procedure is not always applicable or the safest course of action. Instead a common sense approach is allowed, providing it is well considered and the risk managed accordingly.

There is risk everywhere in the fire safety industry. Thankfully, due to the high level of standards and procedures laid down for the aviation industry, the chances of a fire are generally low. Alongside this, with aircrew regularly receiving training and following procedures, flying in an aircraft is rightly regarded as a safe place to be and that the crew are thoroughly trained to ensure the safety and security of all passengers.

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