Controversy Continues Over Long Distance Twin-Engine Flights

Air Safety Week, August 9, 1999

Passengers may notice a louder noise from the side of the airplane with the one remaining engine laboring to keep the airplane airborne, while a pronounced silence, other than the noise of the slipstream, may prevail on the side with the dead engine. Crew and passengers are under increased stress, full in the knowledge that the airplane is down to one engine, and that loss of the remaining powerplant means the airplane is going down. Three hours is a long time to be under this heightened level of stress, sources say.

The divert airfield is notified by satellite telephone and acknowledges its readiness.

As the airplane proceeds on one engine, and loses weight as fuel is consumed, the flight crew periodically increases altitude to reduce fuel consumption. The airplane makes an uneventful landing at the divert airfield; the crew, having practiced in the simulator, easily copes with the absence of reverse thrust from the dead engine.

* Scenario #2: Multiple mechanical failures. Foul weather below 20,000 ft. Winter in the Northern Pacific. In this case, the engine loses a fan blade, which forces an immediate shutdown. Even so, the now-unbalanced blade assembly freewheeling in the air causes the entire airplane to vibrate violently. As Airbus' John Lauber said, the vibration means not a few moments of fear, but hours of gut-wrenching anxiety. The cockpit crew has not experienced anything like it in the simulator. Passengers may be really frightened; some may panic.

The bad day gets worse. The bleed air and the generator on the remaining engine are lost. Unable to maintain cabin pressurization, or heat, the aircraft must descend to 10,000 feet, which will put the airplane into bad weather. With the loss of cabin heat, the once comfortable 77 degrees F temperature plummets in the space of an hour to about -40 degrees F. The same temperature will prevail in the unheated cockpit, too. Passengers are now in an unheated cabin that is vibrating severely. As back-up generating power fails, the crew cuts power to the cabin bus, and the lights go out.

The divert airfield does not respond to repeated calls on the satellite telephone. In any event, the divert airfield

has neither the vehicles nor the facilities to disembark and protect 200 passengers from the frigid winter weather. The airfield also is depending upon off-site rescue and firefighting resources (ARFF), which are not contacted because of the communications breakdown.

After struggling through unexpectedly heavy headwinds flying at 10,000 feet, the airplane arrives in a critical fuel state, with no time for a go-around. In addition, hydraulic and electrical systems failures have deprived the crew of flaps, slats and anti-skid brakes. The high-speed landing causes all tires to blow out and the aircraft skids off the end of the runway. All aboard die from exposure to the bitterly-cold Arctic winter conditions before they can be rescued.

* Scenario #3: In-flight fire. The fire warning light for the forward belly hold illuminates right at the maximum diversion flight time. The crew activates the Halon fire knockdown/suppression system, which is designed to maintain a 3% concentration for 222 minutes (207 minute ETOPS diversion plus a 15 min. reserve). With both engines functioning normally, the crew maintains altitude and airspeed, and heads immediately to the divert airfield. Because of anticipated headwinds, the airplane carries sufficient fuel to remain airborne for 252 minutes (222 minutes plus 30 minutes). In other words, the airplane is carrying a capacity to remain in the air longer than the amount of time provided by the fire suppression system. Halon is exhausted on final approach, the fire rages out of control, burning into the cabin during rollout. Half the passengers are killed by flame, smoke inhalation and toxic gases before the emergency evacuation is begun.