Investigation Summary
The upset began while the aircraft was cruising at Mach 0.82 (approximately 296 knots calibrated airspeed) at 33,000 feet. A relief crew member (likely the captain), seated in the right seat to instruct the first officer, was attempting to troubleshoot a discrepancy in the flight management computer's economy speed calculation. While reaching for the Control Display Unit (CDU), he likely nudged the flap/slat handle, which was located nearby. Due to a design characteristic of the MD-11, the handle was biased toward the aft (extension) direction and could be easily dislodged from the UP/RET position. As the slats extended, the aircraft's center of lift shifted, causing a significant nose-up pitch. The autopilot initially attempted to compensate but eventually disconnected. The captain, facing a sudden stall warning and rapid pitch change, pushed the control column forward with excessive force. The MD-11's light longitudinal control forces at high altitude, combined with the pilot's lack of high-altitude upset recovery training, resulted in a Pilot-Induced Oscillation (PIO). The aircraft underwent several cycles of extreme pitch changes, ranging from +2.0G to -1.2G, before the crew regained control at 28,000 feet.
Final Conclusions
The NTSB concluded that the probable cause was the inadequate design of the flap/slat actuation handle by the Douglas Aircraft Company, which allowed it to be easily and inadvertently dislodged from the UP/RET position. Contributing factors included the MD-11's light control force characteristics in cruise, a lack of specific pilot training for high-altitude upset recovery, and the influence of the stall warning system on the captain's responses. The severity of the injuries was attributed to the lack of seat belt usage by many occupants.
Photographic Evidence (1)
Video Analysis
A Nightmare Over The Pacific | China Eastern Airlines Flight 583 — An MD-11 experiences violent pitch oscillations over the Pacific after an accidental slat deployment, leading to a harrowing emergency landing in the Aleutian Islands.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Systems & Failure Modes
Flap/Slat Actuation Handle
The control handle used to deploy wing surfaces; its design was found to be prone to accidental displacement from the retracted position.
Leading-edge Slats
Aerodynamic surfaces on the front of the wing that increase lift; their deployment at high speed caused the initial pitch-up upset.
Stall Warning System
A system that provides stick shaker and audio alerts; its activation during the oscillations influenced the pilot's aggressive control inputs.
Interesting Facts
- 01The MD-11 involved had logged 4,810 airframe hours and 1,571 cycles at the time of the accident.
- 02G-forces during the oscillations ranged from 2.0G to -1.2G.
- 03156 people were injured (149 passengers and 7 crew members), with 53 sustaining serious injuries.
- 04The passenger cabin sustained substantial internal damage, though the airframe remained structurally sound.
- 05Many passengers were not wearing seatbelts at the time of the upset, which significantly increased the injury count.
Safety Actions & Advisories
Flap/Slat Handle Redesign
The NTSB recommended and the manufacturer implemented changes to the flap/slat handle to prevent accidental deployment, including increased resistance and mechanical gates.
Upset Recovery Training
The accident highlighted the need for specific pilot training regarding high-altitude upsets and the unique handling characteristics of the MD-11.