Ladies and Gentleman:

I am here today as a representative of the Air Line Pilots Association. I have been a safety volunteer and “tin kicker” with the Air Line Pilots Association for over 16 years. I have been a licensed pilot for 40 years and flown for Delta Air lines for 29 years. My background of scientific and engineering training has helped me in these endeavours, but my real job is flying a large aluminium tube filled with wires, electricity, flammable liquids, a lot of flammable material and people. My purpose here today is to challenge you and this industry to help us come up with a better methodology to combat fire on board aircraft.

Many countries throughout the world are enacting regulations that will protect their citizens from electrical arcing problems as well as regulations requiring fire detection and protection for home residences. In the year 2002, the United States National Electrical Code will propose to require arc sensing or “ticking fault” circuit breakers in new residential construction. Some local codes already require all new residential buildings to have an automatic fire detection and fire extinguishing systems. Most countries require some form of automatic fire detection and fire extinguishing systems in commercial buildings.

In the year 2002 it is very likely that the aircraft industry will be building aircraft that will hold more than 600 passengers. Yet there is no requirement or planned requirement for these new aircraft to use arc sensing circuit breakers, or to use fire detection for the hidden cockpit areas, avionics or enclosed cabin compartments (except the lavs), and no requirement for automated fire extinguishing systems for these areas. 

At present the only automated systems required on board modern aircraft are the automatic fire detection systems for the engines and cargo compartments and the lavatory waste receptacle fire bottles. Manually operated extinguishers are provided for the engine and cargo areas. Pilot controlled fire extinguishing systems exist for both these areas. Some aircraft have overheat detection in the avionics compartments but no automated fire extinguishing system. We need an integrated system to detect and extinguish fires in our aircraft, wherever they occur, before they can damage the aircraft or its systems.

Since 1996, there have been three major aircraft accidents involving fire in the cockpit and cabin.  Two had no fire detection system; those accidents were fatal. The aircraft involved in the third accident had smoke detection that enabled the crew to land before the aircraft was severely damaged. This should make it clear that fire detection saves lives.

There have been numerous reported incidents of fire and smoke in both the cockpit and the cabin in the NASA Aviation Safety Reporting System (ASRS) database. We need to examine these events and modify aircraft design philosophy and checklist design philosophy to eliminate the problems highlighted in those reports.

The facts are that present modern wide-body aircraft have up to 200 miles of wiring. There are aircraft presently in the design stages that are contemplating additional uses of electricity throughout the aircraft. We believe that electrical system fire hazards are likely to increase in frequency if nothing is done to change the present prevention, detection and suppression philosophy.

Flight Deck Fire Detection and Protection

One only needs to look at the convoluted and complex “abnormal” or emergency procedure checklists dealing with fire and smoke to get an idea of how the current philosophy for fire detection and fire control is unacceptable.    At the first sign of smoke the crew is required to don their oxygen mask. While this is beneficial for protecting the crew, it severely curtails their ability to use their sense of smell to determine the effectiveness of their next actions in de-energizing/controlling the cause of the smoke. At present there are no detectors in the aircraft to help the crew determine where the smoke may be coming from other than those required for the engines, cargo compartments and lavatories. Our aircraft need detection systems similar to our own central nervous system, ones capable of determining not only the origin of the smoke but the factors causing the smoke. (i.e. Electrical, oil, cigarette)

Numerous problems in the cockpit suggest that fire protection for the cockpit needs a complete rethinking. The space behind sidewall and ceiling panels in the cockpit comprise a very large area relative to the amount of essential control systems present, yet there is no fire detection nor any system for pilot-controlled discharge of fire extinguishing agent to this critical area. Flight crews have no [or limited] knowledge of the airflow in the cockpit and cabin and how this airflow would propagate the flow of smoke/fire. In many of today’s aircraft, if faced with a cockpit fire, the flight crew is unable to get to their fire extinguisher while still attached to their oxygen mask, limited by the length of the oxygen hose to the mask. There are no apertures for applying an extinguishing agent to the likely locations where fire may occur in the cockpit, such as in the avionics bay, behind the glare-shield, in the circuit breaker panel, etc. In the meantime, of course, the crew must fly the aircraft and decide where, how and when they can get the aluminium tube safely on the ground.

Fire Protection in the Cabin

History has shown that fires in the cabin can be even more difficult to attack than fires in the cockpit. While the lavatories have smoke detectors and automatic fire bottles for the trash-can, that is the limit of automated detection and suppression systems. For fire detection, we depend on the cabin crew and passengers. For fire suppression there are fire extinguishing bottles spread throughout the cabin (both halon and water) and the potable water supply is available, as applied via coffee urns. If the fire is not hidden behind structure, the flight attendants may be able to extinguish the fire. However, if the fire is hidden behind cabin structure, it is likely that the flight attendants have no procedures to combat the fire. There is little that can be done by the flight attendant, except to try and work with the flight crew to isolate the electrical power as a potential energy source. In these days as more and more electrical systems are installed in hidden areas of the cabin, we need sophisticated detection systems to advise the cockpit and cabin crews of the precise fire location. There needs to be apertures in the cabin around potential fire zones to aid the flight attendants in applying extinguishing agents directly to burning materials hidden from direct access in the cabin. Until such systems are implemented, our aircraft cabins will continue to be poorly protected.

It is often forgotten that our aircraft are flying at altitudes in which they are 15 to 30 minutes from the closest suitable landing site.  Consider the case of the FedEx DC-10 that had an in-flight fire and received prompt fire warnings.  From the time the alarm sounded at 33,000 feet, it took the crew 20 minutes to land the airplane. We must make changes to better protect our cabin area and we must do it now.

Avionics and E/E Compartments

Avionics compartments have changed in modern aircraft, yet our concepts in fire protection for them have not. While avionics and their electrical systems were historically in one area, our modern air transports with their large cabins and expanding electrical demands now have many new electrical compartments scattered throughout the passenger cabin. The electrical power flowing into the avionics compartment has also increased with no consideration that at some point there should be fire protection provided. But these compartments are not required to have a fire detection system and, of course, thus have no automatic or crew controlled fire-extinguishing system.  This lack of detection and extinguishing capability complicates the crew’s ability to determine if the electrical system is the supplying energy source to the smoke/fire. The ability of the flight deck crews to select the proper course of action is severely compromised.

Is further regulation needed? In my opinion, the answer is “yes.” It appears to me and my fellow pilots that aircraft designers and the airlines will continue to ignore our concerns for more rapid and accurate fire detection and suppression systems until they are ordered to address them. At present we are unable to assure a safe return to ground in the event of an in-flight fire. It is unconscionable that the problems identified continue to exist in our modern age.  However, I am not here just to present you with these problems.  I also want to offer some solutions. 

Possible Solutions

The most hazardous and insidious airborne fire threat is in the aircraft electrical system. However, we believe that the fire threat of this fundamental system can be significantly reduced through just a few initiatives. We recommend establishing a requirement to have circuit breakers that protect against an arcing fault, also known in the industry as an “intermittent” or  “ticking fault.” The industry, especially the United States Navy, is currently working on developing an arc-sensing circuit breaker appropriate for aircraft. With small amount of additional research this option should be available in a relatively short time. Developing the new breaker is only half of the circuit breaker solution. To be truly effective, regulatory authorities throughout the world must require these circuit breakers.  Further, all existing fleets should be retrofitted so they include these devices.

Checklist Procedures

The other effective method to reduce the threat of airborne electrical generated fire would be improving the current abnormal/emergency checklist procedures. Most of the checklists in use today require the crew to “trouble shoot” smoke occurrences to identify the origin of the smoke/fire. Unfortunately, the crew does not have adequate detection tools available to them to try and isolate possible causes. Past accidents have shown that time is of the essence. Thus, a much better methodology would be to simplify the procedure by directing the crew to divert the aircraft and land as soon as possible. This would relieve the crew of trouble shooting the problem. While trouble-shooting may save an airline money (since emergency diversions can be costly), when a fire is advancing rapidly, the delay can be catastrophic. After initiating an emergency diversion, the next step for the crew would be to isolate the electrical system to power only those items required to safely fly the aircraft to a landing, thus removing the ignition source in an electrical fire. This concept is sometimes known as the “virgin bus” or “essential bus.” This essential bus should be able to provide electrical power to essential systems for up to the current ETOPS time limit.

Better Detection

There are many detection devices currently available. The detection systems need significant improvements in reliability. False alarms are far too common in cargo compartments. This will become even more of a problem as more narrow-body aircraft are retrofitted with fire protection systems. However, this is not a reason to deactivate the detectors. Instead, it is reason to consider using different forms of detectors or changing the logic that initiates the fire signal.

The big problem with detection is that there are no requirements to have detection in the majority of areas of the airplane cabin where fires can occur, as previously discussed. Good detector placement can aid immensely in rapidly identifying whether the smoke source is electrical or in the air conditioning system. Placing smoke detectors in each of the ducts being supplied air from the air-conditioning/pressurization packs would be very effective method of determining if the smoke was originating in the air-conditioning/pressurization system. This would eliminate the most common source of smoke the cabin. Locating detectors evenly spaced and close by to electrical system routings throughout the aircraft would give the flight deck and cabin crews a much better ability to isolate and eliminate the source of an electrical smoke/fire.

Suppression Systems

The United States Navy has been working to combat aircraft in-flight fires and shipboard fires for many years. They currently have systems in use in aircraft today that have shown to be effective in fighting fuel tank dry bays and power-train zones. They also have a possible solution to the problem of extinguishing large cabin fires.

Currently, the U.S. Navy has fighter and other combat aircraft flying with a nitrogen-based fire extinguishing system.  This system has been used to successfully extinguish an actual power-train zone fire in an airborne aircraft; it is proven technology. The system as currently configured has both automatic fire detection and extinguishing. The soul of the system is a nitrogen gas generator similar in appearance and process to the chemical oxygen generator system presently used in commercial aircraft. Nitrogen is a non-polluting gas and can be used to extinguish a fire in concentrations that would not be harmful to humans. Suppression systems such as a nitrogen inerting system could prove to be very useful in many areas of our aircraft.

The cockpit is an area where the use of an automatic or pilot controlled suppression system could be of enormous help. As the cockpit is presently designed, there is no ability to direct the fire-extinguishing agent to a fire originating in the area between the cockpit sidewall, ceiling and the aircraft structure (skin, frames and stringers). The cockpit area is probably the most complex area of the aircraft. Every major system of the aircraft is usually routed into the cockpit and space in this area is at a premium. This means there is not a lot of room to add some type of detection and extinguishing system. The advantage of the nitrogen generator is that it occupies very little space. It must be sized to match the required agent with the space being protected; this part of the process yet has to be determined except through testing. The nitrogen gas generator system can be designed to be operated either automatically, manually or a combination of both.

The avionics compartment would be another logical area for installation of fire suppression system. These compartments are located under the cockpit and in various areas of the passenger cabin as well as both above and below the main deck. This then requires a flexible system, one easily controlled, and one that would not cause undue harm to the passengers and crew.

The problem of how to combat cabin fires will probably require a combination of systems, depending on the fire location. Fires in the open area of the cabin can be adequately extinguished by handheld fire extinguishers if the fire is small. For those vast areas of the cabin that are not accessible to the cabin crew or passengers there should a system to discretely apply extinguishing agent to the area where fire is detected. Fires that would originate in these areas could use the nitrogen generators. The passenger cabin has many flammable materials (particularly after years of service collecting oil, lint and debris in dead spaces in the cabin) and many electrical components in the same dead spaces that can ignite that combustible material. If a fire started in one of these dead spaces, it is likely that the equipment presently on our aircraft would not likely be sufficient to extinguish the fire. The U.S. Navy has developed a water misting system that might be able to knock down and extinguish a large cabin fire with very little water.

Conclusion

I hope that this paper has made it clear that the industry has not kept pace with the demand put on it by significant changes to the design of electrical systems on airplanes. There needs to be a great deal of work done to prevent electrical fires from the beginning. We also need systems designed to provide fire detection and suppression in all the possible fire regions in the airplane fuselage, both accessible and inaccessible. Failure to execute these changes will put crews and passengers at an unnecessarily risk to experience a catastrophic in-flight fire, a terrible fate experienced by too many already. We can prevent in-flight fire catastrophes if we want to. We at ALPA stand ready to assist the airline industry in achieving this important, life-saving goal.