China Airlines Flight 006

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China Airlines Flight 006 on February 19, 1985 was a flight from Taipei to Los Angeles. After ten hours of flight the Boeing 747SP aircraft lost power in one of its four engines. Although they had several minutes to do so, the pilots failed to adjust the controls to counteract the asymmetric thrust due to the failed engine. The aircraft eventually rolled over and plunged 30,000 feet, experiencing high speeds and very high forces. The pilots recovered control and diverted to San Francisco. Two people had serious injuries and the aircraft sustained substantial damage.

[edit] The incident

Ten hours out of Taipei, the 747 was flying at 41,000 feet about 350 miles (550 km) northwest of San Francisco when it encountered some turbulence due to the jetstream. This caused the airspeed to vary, so the flight computer adjusted the engine throttles down and up. The righthand outer engine (No. 4) failed to accelerate when commanded and became hung at low power. The flight engineer's attempts to correct this failed, likely because he forgot to close a bleed air valve as the procedure requires. After a minute and a half the engine flamed out, so that all power from it was lost.

The captain was aware of the loss of the engine, and instructed the engineer to attempt a restart (although that needs to be done below 30,000 feet and they were still at 41,000 feet). The captain did not adjust the rudder to counteract the lack of thrust on the right, and kept the autopilot engaged, even though the standard procedure for handling an engine outage is to apply compensating rudder, then to disengage the autopilot and put the aircraft in good balance. The autopilot tried to keep the airplane level and on course by turning the control wheel to the left, balancing the asymmetry causing the plane to want to roll right. This worked for several minutes although it required the autopilot to turn the control wheel more and more to the left. Eventually the autopilot had turned the wheel to the maximum and the aircraft began to slowly roll to the right.

Meanwhile the captain was alert to a continuing decline in airspeed (due to the lack of thrust and increasing drag as the aircraft went out of trim). He set the autopilot to drop the nose to pick up speed, and kept a close eye on the airspeed indicator. About three minutes after the engine problem began, he was still concerned with the falling airspeed and took over control of the plane from the autopilot. He was apparently unaware of the strong left wheel input the autopilot had been using, and also hadn't noticed the substantial right bank the plane had already rolled into. Sensing something wrong he looked at the artificial horizon (AH) instrument and saw the horizon was near vertical. Thinking it was broken, he checked the copilot's AH and the standby AH, and they also seemed broken in the same way. The plane had entered clouds and he could not orient himself by looking through the windows. The plane in fact had rolled over and was in a steep dive, losing 10,000 feet in twenty seconds and reaching abnormally high speeds. The crew and passengers experienced enormous forces, reaching as much as five Gs.

Only after breaking through the bottom of the clouds at 11,000 feet could the captain orient himself and bring the plane under control, leveling out at 9600 feet. They had descended 30,000 feet in under two and a half minutes. The flight crew were under the impression that all four engines had flamed out, but the National Transportation Safety Board believes only engine No. 4 had quit. After leveling out the three good engines were giving normal power and a restart attempt brought No. 4 back into use. They began climbing and reported to air traffic control "condition normal now" and they were continuing on to Los Angeles. They then noticed that the landing gear were down and one of the plane's hydraulic systems was empty. Since they didn't have fuel to reach Los Angeles with the drag added by the landing gear, they diverted to San Francisco. Learning there were injured people on board, an emergency was declared and they flew straight in to the airport and landed without further incident.

[edit] The aftermath

There were two injuries. One was a fracture and laceration of a foot; the other acute back strain requiring days of hospitalization. The aircraft was significantly damaged by the aerodynamic forces. The wings were permanently bent upwards by two inches, and the landing gear and nearby airframe had much damage. Most affected was the tail, where large outer parts of both horizontal stabilizers had been ripped off. The entire left outboard elevator had been lost along with its actuator, which had been powered by the hydraulic system that ruptured and drained.

The aircraft involved in this incident is now used by K.A. Paul and his organization, Global Peace Ambassadors as Global Peace One.[1]