In-Flight Fires Wreak Havoc With Systems Reliability

Air Safety Week, Sept 22, 2003

Awkward emergency equipment and erratic displays complicate coping

There is nothing like the whiff of something burning to have an effect on a pilot akin to a jolt of chilled water to the heart. Fire, and especially an electrical fire - with its potential to directly attack the "nervous system" of a modern jet - is at the very top of the typical pilot's primal fears.

In a recent survey of nearly 100 reports of in-flight fire and smoke, the pilots' hit upon consistent themes: notably the need to cut power to the perceived source of an electrical malfunction, the imperative to land as soon as possible, and the need for more demanding simulator training while wearing emergency equipment.

As the saying goes, fire in an airplane is fundamentally different from fire in a building on the ground because the airborne occupants cannot get out. Buildings can be evacuated. Airplanes must descend and land, oftentimes with fire raging, or smoldering dangerously, with power to key systems shut off.

In-flight smoke and fire events occur with sufficient frequency to generate a thick stack of confidential reports over a three-year period (2000-2003) submitted by pilots to the Aviation Safety Reporting System (ASRS). The database is maintained by the National Aeronautics and Space Administration (NASA) on behalf of the Federal Aviation Administration (FAA).

The rich and varied collection of smoke and fire events has been distilled to a selection of cases showing the many ways the burning odors are first noticed, the initial wisps of smoke first appear, the lights flicker, or the instruments suddenly display a problem message and pilots are forced to shift gears from a routine mindset to the hyper-vigilance of coping with an emergency.

The pilot's reports are de-identified in the ASRS system, and the cloak of anonymity appears to diminish any reluctance they may have in confessing to their own errors. The confidentiality also tends to create an environment that encourages plain speaking. The virtue of ASRS is that a vivid word picture may be worth more than a stack of statistics. That value is plainly evident in the abbreviated vignettes that follow. From these sometimes harrowing accounts, consistent themes emerge:

* It is often difficult, if not impossible, to locate the source of smoke or fire.

* Circuit breakers cannot be quickly located, extending the dangerous time that power can feed an electrical fire.

* Instruments malfunction, flicker, blank out, give false or possibly misleading readings. The erratic pattern of failures can confound troubleshooting. Of course, seemingly unrelated system indications can be a symptom of cascading failure as electrical arcing and fire eats its way through bundles of wiring or closely packed avionics. Fire compromises the "trust your instruments" drilled into every pilot. Rather, "trust but verify" is perhaps the more appropriate guidance.

* Personal protective equipment can be stored in an awkward location, not easily retrieved in an emergency, and communications while wearing the equipment can be difficult - at the very moment when intra-crew and external communications with the ground are critical.

* There is enormous time pressure when faced with in-flight fire. The workload can get very high, very quickly.

* Events progress quickly from the first indication of a problem to an emergency landing.

* Overweight landings are frequent.

* Stress and a fixation on fire can lead to "tunnel thinking" and errors in other areas, such as altitude deviations or misreading instructions from air traffic control.

* Passenger and flight attendant anxiety can contribute to the stress level in the cockpit.

* A third person in the cockpit, be it a relief pilot called forward from the cabin or a mechanic riding in the cockpit jumpseat, can aid significantly in executing checklists and trouble-shooting.

* Smoke often comes from bad seals, leaks and such in engines, auxiliary power units, and air conditioning equipment. Smoke detectors in air conditioning ducts would help greatly in distinguishing these oftentimes less dangerous cases from the ravages of full-blown electrical fires.

* Support personnel on the ground may lack experience, may not be the most helpful and, in overseas flights, may not speak adequate English.

* The proliferation of in-flight entertainment systems has increased the potential for smoke and fire events.

* Recurrent training needs to be more realistic, to include forcing aircrews to communicate while wearing their breathing equipment. The potential for "long range intercom" is increased, wherein a pilot mistakenly radios a message meant for fellow aircrew. In the Swissair Flight 111 case, this happened as the pilots facing the fire approached the moments of greatest stress.

These issues are brought to life in the accounts that follow:

Smoking battery

Case: B777 in cruise at 37,000 feet declared an emergency due to a main battery overheating with smoke and fumes.