This video analyzes the preliminary Air Accident Investigation Authority (AIA) report on a Boeing 747 freighter runway excursion in Hong Kong. The report refutes initial speculation and identifies a bizarre cause for the accident. During a normal landing rollout, the No. 4 engine—which had a known, inoperative thrust reverser—unexpectedly accelerated to 107% N1 forward thrust. The flight data recorder confirmed the corresponding thrust lever was in the full forward position. This massive asymmetric thrust caused the aircraft to veer uncontrollably off the runway, leading to its destruction and the deaths of two people in a ground vehicle. The central mystery, as far as I can tell, is why the thrust lever moved and why the flight crew apparently failed to notice and correct such a critical and visually obvious failure.
Analyzing the Hong Kong 747 Crash: A Breakdown of the Preliminary Report
0:00:03 - A Strange Accident: The host presents the official preliminary report on the UAE 9788 flight, a 747 freighter that veered off the runway in Hong Kong. The actual cause is stranger than initial theories like a porpoised landing.
0:01:03 - Routine Landing: The aircraft was on a normal ILS approach with a minor crosswind. The co-pilot was the pilot flying, which is a standard procedure.
0:09:02 - Key Inoperative System: The aircraft was dispatched with an inoperative thrust reverser on the number four (outboard right) engine, which was documented in the minimum equipment list (MEL). This is a critical factor in the accident.
0:09:35 - Normal Initial Rollout: After touchdown, the landing sequence was standard: speed brakes deployed, and reverse thrust was applied to the inboard engines (#2 and #3). The auto brakes disengaged as expected, and the crew initiated manual braking.
0:12:16 - The Critical Failure: About 30 seconds after touchdown, the No. 4 engine began accelerating to full forward thrust, eventually reaching 107% N1.
0:12:46 - Catastrophic Asymmetric Thrust: The immense forward thrust from the outboard No. 4 engine, while other engines were in reverse or at idle, created a powerful turning force. This caused the aircraft to swerve sharply to the left and exit the runway.
0:16:10 - The Unexplained Thrust Lever: The report reveals the No. 4 thrust lever itself was found in the full forward position. How it got there—whether by system error or pilot action—is not explained. It's a head-scratcher why neither pilot noticed this.
0:19:35 - Remaining Questions: The report clarifies what happened (No. 4 engine at full forward thrust) but not why. The primary questions are what caused the thrust lever to advance and why the crew failed to identify and correct the problem.