A couple of days ago, India’s Aircraft Accident Investigation Bureau (AAIB) released its preliminary report into the tragedy of Air India flight AI171, the Boeing 787-8 that crashed seconds after taking off from Ahmedabad, killing 260 people.
The preliminary report simply shares the facts as they’re known, and doesn’t draw any conclusions. That being said, the United States’ Federal Aviation Administration (FAA) has just released a memo about the Boeing 787 fuel control switches, which is pretty telling…
FAA suggests fuel control switches were moved manually
As a reminder, the investigation into the crash of AI171 is centered around the aircraft’s fuel control switches. Investigators know that these were moved from the “RUN” to “CUTOFF” position just moments after takeoff, one second apart.
Ordinarily, these switches are only moved on the ground when starting or stopping engines, or in the air during an emergency. However, you’d never use them just seconds after takeoff, when there are no signs of engine issues, since there’s no chance to recover at such a low altitude.
In the cockpit voice recorder, one of the pilots was “heard asking the other why did he cutoff,” and “the other pilot responded that he did not do so.”
So anyway, one big question has been whether a human actually manually moved these switches, or whether there was some horrible technical or mechanical failure that somehow caused the switches to move positions.
While the AAIB has been leading the investigation, the FAA has been providing technical support, so is always aware of the details of the investigation. When there was talk of something involving the fuel control switches, some people pointed out a December 2018 Special Airworthiness Information Bulletin (SAIB), regarding potential disengagement of the fuel control switch locking feature on Boeing 737s, based on reports that the fuel control switches were installed with the locking feature disengaged.
However, that doesn’t appear to be the case here. Per the document:
Although the fuel control switch design, including the locking feature, is similar on various Boeing airplane models, the FAA does not consider this issue to be an unsafe condition that would warrant an Airworthiness Directive on any Boeing airplane models, including the Boeing 787.
In other words, the FAA seems confident that the fuel control switches as such are safe. I don’t think that’s terribly surprising, though it really only leaves one other explanation…
Why did a human move the fuel control switches?
With the FAA essentially confirming that there’s nothing wrong with the Boeing 787’s fuel control switches, that makes it pretty clear that investigators believe this accident happened because a human moved the switches. The question is, why would a human move the switches to “CUTOFF,” when that was guaranteed to send the plane straight into the ground?
It’s hard to envision a scenario where this was done accidentally, especially just a few seconds after takeoff, during the most critical phase of the flight. I would imagine the information that hasn’t been released yet is probably pretty telling.
As of now, the only thing we know about the conversation between the two pilots is how “in the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff,” and “the other pilot responded that he did not do so.” I think the next interesting details will be:
- What was the conversation before and after that happened?
- Was it the captain or first officer asking that question?
With the first officer being the pilot flying and the captain being the pilot monitoring, the captain would’ve been the one more likely in a position to move these switches without it being super obvious (since the pilot flying is using both hands, initially for the yoke and thrust, and then just for the yoke). That assumes there was no one else in the flight deck (and there’s no mention of anyone else in the flight deck in the preliminary report).
It’s hard to imagine any situation in which this could happen by accident, especially if the (much more experienced) captain was the one who moved the switches…
Bottom line
The FAA has released a memo reassuring airline operators that there are no issues with the Boeing 787 fuel control switches, since those switches are the center of the investigation into Air India’s 787-8 crash. I don’t think this is terribly surprising, but it’s also a good clue that the investigation is likely centered around the human factors here, rather than some horrible design flaw that could impact other flights.
What do you make of this FAA memo, and its implications?
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