AI-171 crash: Aviators debate Boeing's fuel switch issue, pilots' actions

The Indian Government's preliminary report into the June 12th Air India 171 Boeing 787-8 Dreamliner crash in Gujarat, mentions that the plane's fuel control switches (which can turn on/off fuel flow to the engines) switched from "Run" to "Cutoff" sequentially post-takeoff(few seconds after takeoff). The fuel switches being turned off has led to the starvation and stoppage of the plane's twin engines. The preliminary report mentions that in the cockpit audio, one pilot asks the other - "why did you cutoff?" and the other pilot replies "I didn't".

The aircraft flying Ahmedabad-London had crashed about 40 seconds after takeoff, killing 260 people, which includes passengers and those at the crash site (a hostel), making it among the worst aviation disasters in India.

The mystery of crucial fuel control switches seemingly getting turned off without pilot intervention (as indicated by cockpit audio mentioned in the Government probe report), has raised suspicion among a section of senior aviators. These aviators are posing serious questions to Boeing, the American planemaker, whose jets have faced multiple crashes and safety-related, quality-related incidents in recent years.

American FAA report highlighted issues with Boeing Fuel Switches

Citing a December 17th, 2018 information bulletin from America's Federal Aviation Administration (FAA), senior aviators point out to WION that the US firm Honeywell-made fuel switches on Boeing planes have been a cause for concern. With the subject line "Engine fuel and control" the FAA bulletin mentions the "potential for disengagement of the fuel control switch locking feature" in more than two dozen popular variants and sub-variants of Boeing planes, including the 787-8 Dreamliner model which crashed in Gujarat.

In the advisory from 2018, FAA recommended Boeing fleet operators with "affected planes" to: "Inspect the locking feature of the fuel control switch to ensure its engagement. While the airplane is on the ground, check whether the fuel control switch can be moved between the two positions without lifting up the switch. If the switch can be moved without lifting it up, the locking feature has been disengaged and the switch should be replaced at the earliest opportunity."

The advisory also mentions, "for Boeing Model 737-700, -700C, -800, and -900ER series airplanes and Boeing Model 737 8 and -9 airplanes delivered with a fuel control switch having P/N 766AT613-3D: Replace the fuel control switch with a switch having P/N 766AT614-3D, which includes an improved locking feature." We request that owners and operators report any failure of the locking feature of the fuel control switch to Boeing, America's FAA mentions in the advisory.

‘Air India did not carry out fuel switch inspections’

According to the preliminary report released by the Aircraft Accident Investigation Bureau(AAIB) of the Indian Government's Ministry of Civil Aviation(MOCA), Air India did not carry out the fuel switch inspections as suggested by FAA, as it was an advisory and not mandatory. Further it mentions, the throttle control module was replaced on the crashed VT-ANB (crashed AI-171) in 2019 and 2023.

However, the replacement of throttle control module was not linked to the fuel control switch, the report says. There has been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB(crashed AI-171), the preliminary report mentions.

"Takeoff is a very critical maneuver and it is done not via autopilot, but physically by one of the pilots. One pilot is fully focused on pulling the yoke so that the aircraft lifts off at three degrees per second to achieve 15 degrees in five seconds. The other pilot is busy monitoring the aircraft pitch angle, airspeed, the rate of climb, and the altitude. These are all very critical and focused jobs. This is not the time pilots are playing with fuel switches," a senior aviator told WION, on the condition of anonymity.

Explaining the Boeing's fuel control switches, the aviator told WION, "think of the Boeing jet as a car... every time you start the car, you have to turn ON fuel switches and then put the key... After that, the switches have to be checked again. In comparison, Airbus in their A320 fleet and later models don’t have dedicated fuel cutoff switches, Airbus just has one master switch for the engine. Boeing's fuel switch is an old technology and the FAA report shows there were issues with it," he opines.

‘Fuel switches turned off one after another, then turned back on’

According to the preliminary report released by Indian authorities, the fuel switches on the taking-off AI-171 plane were turned OFF one after another, with a one second gap. A few seconds later, the fuel switches of both engines were turned back ON, the report says.

Captain Mohan Ranganathan, a veteran aviator(retired) who has clocked over 20,000hours of flying over four decades, told WION that one must carefully observe the report of fuel switches initially getting turned OFF - one after another, with a one second gap between them. He also highlights the portion of the report which says that both fuel control switches are getting turned back ON later. He suggests that this transition between ON-OFF-ON possibly indicates manual intervention, as the switches cannot be operated without physically moving them.

When asked about the 2018 FAA bulletin on Boeing's fuel control switches, Ranganathan said that the advisory was not mandatory and was an advisory. He also referred to the track record of the Boeing 787 Dreamliner, which has not had any fatal accidents since its first flight in 2011. The AI-171 is the first such fatal accident involving this type of aircraft.

However, Ranganathan also raises questions about the Indian Government's report and asks why some parts of the report are deliberately left unclear. He points out to the verbal exchange between the two pilots regarding the fuel control switch being turned off. "Why does the report not mention specify who among the two aviators asked the question and who answered? This can be easily identified and revealed based on the recordings available," he remarked.

‘No significant bird activity, plane started losing altitude before crossing airport wall’

The Government's preliminary report also mentions that there was no significant bird activity observed in the vicinity of the flight path and that the plane started to lost altitude before crossing the airport perimeter wall. "Investigation is continuing and the investigation team will review and examine additional evidence, records, and information that is being sought from the stakeholders.