Indian aviation authorities have released the preliminary report on the Air India flight 171 crash that occurred just minutes after take off from Ahmedabad airport , killing 241 of the 242 people on board. While it pinpoints the proximate cause of the Boeing crash, it leaves unresolved how that came about.
The proximate cause is that the engine fuel switch to both engines was switched to the ‘off’ position.
According to a preliminary report by India’s Aircraft Accident Investigation Bureau, moments after take-off both the switches in the cockpit that controlled fuel going to the engines had been moved to the “cut-off” position. Moving the fuel switches almost immediately cuts the engine.
…According to the report, the fuel switches were moved to cut-off “one after another”. Seconds later, the switches were moved back to turn the fuel back on and one of the plane’s engines was able to restart, but could not reverse the plane’s deceleration.
As one would expect, there are safeguards supposedly in place to prevent the switches being accidentally turned off.
The preliminary findings did not say how the fuel switches could have flipped to the cutoff position and cut-off the engines. The switches are equipped with safeguards, including a locking mechanism, to prevent accidental movement.
They are most often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report does not indicate there was any emergency requiring an engine cutoff.
A US aviation safety expert, John Cox, told Reuters a pilot would not be able to accidentally move the fuel switches that feed the engines. “You can’t bump them and they move,” he said.
“If they were moved because of a pilot, why?” asked US aviation safety expert Anthony Brickhouse.
But the text of the full report does say that “the fuel control switches were installed with the locking feature disengaged” [my italics] but that this “was not considered an unsafe condition that would warrant airworthiness directive (AD) by the FAA”. Some are suggesting that this may be the source of the problem.
Mr Pruchnicki said he’s wondering whether there was a problem with the fuel control switches.
“What does this [bit in the report] exactly mean? Does it mean that with a single flip, that switch could shut the engine off and cut the fuel supply? When the locking feature is disengaged, what exactly happens? Could the switch just flip itself to off and shut down the engine? If that’s the case, it’s a really serious issue. If not, that also needs to be explained,” he said.
…Capt Kishore Chinta, a former investigator with India’s Aircraft Accident Investigation Bureau (AAIB), wonders whether the switches tripped because of a problem with the plane’s electronic control unit.
“Can the fuel cut-off switches be triggered electronically by the plane’s electronic control unit without movement by the pilot? If the fuel cut-off switches tripped electronically, then it’s a cause for concern,” he told the BBC.
The idea that the pilots, both experienced, would have deliberately or accidentally switched them off seems preposterous.
The commanding pilot of the Air India plane was Sumeet Sabharwal, 56, who had a total flying experience of 15,638 hours and, according to the Indian government, was also an Air India instructor. His co-pilot was Clive Kunder, 32, who had 3,403 hours of total experience.
…Drawing on information gathered from the plane’s data and voice recorders, which were recovered after the crash, the report relayed that “in the cockpit voice recording, one of the pilots is heard asking the other why did he cut off”, referring to the fuel switch.
“The other pilot responded that he did not do so.” Seconds after, the plane began losing altitude and an emergency message was transmitted from the cockpit to air traffic control, just before it crashed to the ground outside the airport perimeter.
The possibility exists that some malfunction led to the switches being moved to the off position without any pilot action, especially since the locking feature had not been engaged when installed.
More details and the full text of the preliminary report can be found here.
It is not clear when the full investigation will be completed and the final report released.
I highly recommend the Captains Speaking podcast about the preliminary report: https://www.youtube.com/watch?v=ka8RYplHD7Y
It’s done by two 737 training captains who really know their stuff and are very careful about speculation. They were kind of baffled by the reporting about a locking mechanism for the fuel switches; there’s a detente but no lock as such. They thought the airworthiness bulletin was included more for completeness than anything else, as if there was an actual known safety issue with the design of the switched there would have already been an airworthiness directive with required issued.
Here’s a video that does a good job describing the report.
https://www.youtube.com/watch?v=00ooqCuRoU8
The important thing is that one pilot cut off the engines, probably deliberately. And the report says they have brought in “Experienced Pilots, Engineers, Aviation Medical Specialists, Aviation Psychologist, and Flight Recorder Specialist”. You figure it out.
#2: It reads like you are emphasising and leaping to infer a psychological ill-health issue, ahcuah. That’s unwarranted, particularly at this stage. Other potential psychological factors remain in scope, such as events which could cause disorientation, startled reactions, misunderstanding or mis-operation, inadequate crew management (communications and behaviour between the crew) to think of just a few. Correctly assessing those and weighing any contributions will require an experienced professional. As you say, “figure it out”.
I have been reading Admiral_Cloudberg on reddit / Medium for years now and one of the most important things I’ve learned is that the final report will take years and may actually diverge in important ways from the preliminary report. Pilot error or not, we won’t know for months still.