Vulnerability to Uncontrollable Smoke & Fire Can be Reduced

Extended-Range Aircraft at Greater Risk Due to Longer Distance From Airfields
The threat posed by dense continuous smoke and fire in the cockpit and cabin has received insufficient attention in new rules proposed for extended-range operations (ETOPS), according to two commentaries on the subject.

The Federal Aviation Administration (FAA) received more than 135 comments from individuals, companies, operators, passenger groups, associations, unions, and individual persons on its notice of proposed rulemaking (NPRM) for 180-minute ETOPS (see ASW, Dec. 15, 2003). The comment period closed March 15, and the volume of submissions indicates the high interest in ETOPS. The updated rules could allow some operators to save on fuel and time, while costing other operators in terms of added equipment requirements.

The FAA concept, based on extensive discussions with industry, proposes to allow twin-engine airplanes to fly more direct routes that could be as far as 180-minutes flying time from a divert airport in the event of an engine failure or belly hold fire (see ASW, Jan. 13, 2003; March 24, 2003). The NPRM is based on the philosophy of prevent and protect. First, to prevent the need for a diversion in the first place through increased reliability and redundancy. Second, in the event of an emergency, to protect sufficient residual capability to assure that the airplane can safely make it to a divert airfield and land under instrument conditions after a missed approach.

While much attention is focused on engine reliability, the NPRM's focus on the in-flight smoke and fire threat was almost exclusively relegated to a cargo bay fire, and supplying 195 minutes of fire suppression, which would allow a 180-minute flight to a divert airfield plus an additional 15 minutes for a missed approach and final landing.

However, the greater threat may be above the belly holds, on the main deck - an area where the NPRM appears to be in the non-engagement mode. Many fittings, panels and other items are made of flammable material, fire suppression is limited to hand-held extinguishers, and dense smoke in the cockpit could rob the pilots of their ability to see vital instruments and maintain vision through their windscreens in order to safely land the airplane.

Of the many comments submitted on the NPRM, two address the main deck fire threat directly. They were submitted by the Aircraft Services Group of Ramsey, N.J., and the International Aviation Safety Association (IASA). The former offers technology - purchased by the FAA for its airplanes - enabling pilots to see their instruments and also out the windscreen should the cockpit become filled with smoke. IASA was formed and is supported by the wife of a man who died in the 1998 crash of Swissair Flight 111 from an in-flight fire. The IASA comment was prepared by her staff and reflects an appreciation of the issues involved. Both comments cite various independent studies showing that the risk of an in-flight smoke and fire event is about twice as likely as an in-flight engine shutdown.

A few preliminary comments are in order. First, the quantity of wiring and electrical systems in modern jets has gone exponential and therefore so has the threat. The amount of wiring in a cabin in-flight entertainment (IFE) system, for example, can equal the amount of wiring in the rest of the airplane.

Second, while relatively few airborne fires are potentially catastrophic, there are enough accidents and incidents to show how quickly an in-flight fire can become irretrievable once electrical systems are compromised and smoke builds. The NPRM hardly mentions these realities; the closest it comes is its discussion of a belly hold conflagration and the ETOPS divert time being limited by cargo hold suppression capability and duration.

Third, few pilots would opt not to shut down an engine where a caution light indicates falling oil pressure. However, existing checklist philosophies justify - some say forces - pilots to continue operating an electrical system that is showing definite signs of distress and incipient failure - while trying to track down the exact cause. Such protocols suggest a lack of built-in redundancy and the need to de-power quickly most electricals, allowing pilots to revert to a fallback position.

John Farley, a noted test pilot, said, "If I was involved with flying ETOPS, I would be pressing to sit down with the manufacturers' electrical and systems experts to agree what services could be dumped ASAP after the smoke started or was smelled. I mean everything not essential to cruising towards the nearest diversion [airport]. That would mean hand flying on standby instruments with occasional use of a radio - every 15 minutes to check in, etc. Everything else would be switched off. I would then want to know the minimum I could switch on for a hand flown IMC [instrument meteorological conditions] descent and landing, depending on the destination weather."

With these thoughts as preamble, the case made by IASA and Aircraft Services Group (ASG) takes the following form:

General:

The ETOPS Working Group overlooked the impact of smoke-related events on safety and the increased risk associated with the inability to land immediately.
When the source of smoke is not readily apparent, flight crews are trained to follow checklist troubleshooting procedures, most of which involve removing electrical power or isolating an environmental system. The longer it takes to complete a prescribed checklist that is designed to de-energize a smoke source, the greater the chance that the smoke source could intensify or become an ignition source and start a fire.
There is no assurance that the smoke can be evacuated. This is because no aircraft flying today has been certified to FAA recommended standards for cockpit smoke control.
Two issues further compound the issue of continuous dense smoke:
First, current regulations mandate less-stringent flammability standards to those materials intended for use within the pressure vessel but that are outside the occupied areas.
Second, fire detection sensors are [only] required on the propulsion system, lavatories and cargo compartments.

Rule considerations:

Establish smoke detection system reliability standards for ETOPS that equal or exceed propulsion system reliability standards.
Assure that the flight crew's ability to deal with "non-normal" worst-case system failures includes smoke that could be statistically expected to occur in service.
The crew should have a readily available supply of breathable air for use during a prolonged period of smoke contamination.
Classify cabin smoke prevention, detection and fire-fighting capability as ETOPS significant systems.
Additional considerations:
In its incipient stages, the most likely in-flight fire scenario would involve an uncontrolled fire comprising known flammable materials. As there are no mandated toxicity criteria for materials used within aircraft, some of these materials are likely toxic when burned. While the crew is equipped with breathing apparatus that allows them to continue to function, the passenger oxygen delivery system is of limited duration and is designed to be used only for descent in a depressurization event. Because the inhaled mixture includes a high proportion of cabin air, the "yellow cups" will not protect against smoke or inhaled toxins.
Some in-flight fires have been resolved with minimal on-board firefighting coupled with immediate action to land the aircraft (with the flight crew donning smoke-masks and goggles). However, immediate access to an emergency airport may not be an option, such as during a transoceanic flight. Passengers could suffer from prolonged exposure to combustion byproducts with an unknown impact on their survival. Standards need to be set limiting the amount of toxic emissions released by burning materials within an aircraft, and by eliminating the use of materials that sustain a fire.
ETOPS aircraft should meet the currently optional standards for continuous smoke protection in Advisory Circular AC 25.9A. This initiative would ensure that in the presence of continuous smoke in the flight deck, the crew would not be deprived of vision. IASA/ASG propose the following additional provisions in the NPRM to address this deficiency:
A means shall be provided to prevent continuous contamination of the flight deck by smoke from depriving the crew of vision, from the design eye position, which means -
Clear vision outside in the general field of the intended direction of flight,
Clear vision inside of the primary flight information needed for flight control, navigation and aircraft systems required to control the aircraft and monitor its progress,
Required checklists and navigational materials.
Justification:

The Transportation Safety Board (TSB) of Canada's August 28, 2001, "Material Flammability" recommendations proposed a uniform and comprehensive approach in order to reduce the incidence of smoke/fire scenarios and in order to prevent a repeat of a Swissair Flight 111 total loss scenario. Until such time as the FAA adopts these recommendations, the inherent material flammability risks warrant that attention is focused on optimizing the means available to confront a smoke/fire situation. Thermal acoustic insulation blankets like those blamed for quickly propagating the Swissair 111 fire are still in situ throughout the world airline fleet.
For smoke mitigation, a standard that has been established and certified is available. For example, in 1989 the FAA approved cockpit emergency vision technology under a supplemental type certificate. As of 2003, more than 1,500 such systems are in service worldwide, in a variety of aircraft. Such systems also are being installed in more than 45 aircraft operated by the FAA. The passengers and crews aboard ETOPS aircraft merit the same degree of protection as has been afforded by such equipment in FAA aircraft.
To summarize:

The crew must stay focused on fire suppression - eliminating the source.
Cockpit smoke becomes the primary focus of crew attention during fires.
ETOPS flights involve an increased risk of cockpit smoke becoming a survivability factor because of the distance to a divert airport.
Most fires are not controllable or accessible by the crew. Fires may be hidden, of unknown origin or inaccessible due to the legal requirement for both pilots to remain at their station and on oxygen.
Present disparities with respect to material flammability standards increase the likelihood and seriousness of smoke/fire scenarios.
In-flight smoke contamination is a leading cause of diversions.
Smoke is a statistical risk for causing crew incapacitation.
Crew smoke protection should be required for 180+ minutes ETOPS.
Cabin crews need to be trained to a standard technical knowledge that will prepare them to effectively inspect, report and fight a fire.
To conclude:

Aircraft involved in ETOPS flights cannot "land ASAP," yet that is the avowed industry-wide solution since Swissair Flight 111 proved the vulnerability of modern aircraft to in-flight fire.
While the risk of losing an aircraft due to fire cannot be calculated, the event would cause the public to lose confidence in the safety of ETOPS flights.