The Air India flight AI 171 that crashed in June apparently ended in a terrible tragedy due to an abrupt interruption in the fuel supply: The two fuel control switches on the Boeing 787-8 Dreamliner were switched from “RUN” to ‘CUTOFF’ within a second – exactly the command that abruptly shuts down the engines.
The cockpit voice recorder then picks up one of the pilots asking, “Why did you switch it off?” The other replies, “It wasn’t me.” Shortly thereafter, both GEnx-1B engines lose thrust, the aircraft descends uncontrollably, and a Mayday is sent out. Just 70 seconds after takeoff, the aircraft crashes into a densely populated residential area near Ahmedabad Airport on June 12.
260 fatalities, one survivor
Of the 242 people on board – 169 Indians, 53 Britons, seven Portuguese, one Canadian and twelve crew members – only one passenger survives. Another 19 residents die on the ground; dozens of houses are destroyed.
“Unlikely mistake”
Experts are baffled: the switches are well protected on the center console and have a locking mechanism. “Accidental switching is practically impossible,” says US aviation expert Anthony Brickhouse. The preliminary investigation team found no evidence of technical defects in the switches or the fuel system – and there are no signs of sabotage so far
. Air India emphasizes that the twelve-year-old Dreamliner was “regularly and properly maintained” and that both pilots had more than 14,000 flight hours. Why – and by whom – the fuel valves were closed remains the central mystery. Investigators are now looking into
- human error (confusion of switches, stress reaction),
- deliberate action in the cockpit,
- and an electrical malfunction in the switch logic, which is currently considered highly unlikely.
Technical background
On the Boeing 787, the fuel control switches consist of solid toggle switches with a “lift & move” safety mechanism. In the RUN position, solenoid valves open the fuel flow from the main tanks to the combustion chambers; the CUTOFF position blocks this path completely. Normally, the levers are only used at the gate when the engines are shut down. A double failure of both engines after takeoff is therefore classified as “extremely unlikely” (< 1 × 10⁻⁹) in the certification documents.
Further steps
The AAIB has announced the following for the coming months:
- Detailed evaluation of the switch contacts and relay path analyses
- Human factors investigation of duty schedules, cockpit conversations, and possible stress
- Simulation flights with identical scenarios in Farnborough
A final report is expected in a year at the earliest.
Image:
APA
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