Air India

The Ahmedabad crash: accidental or deliberate?

David Learmount Uncategorized , , , , , , , , , , , , , , , , , ,

The movement of two small switches on the aft end of the flight deck centre console, reachable easily by both pilots, appears to hold the key to what happened to the Air India Boeing 787-8 that crashed fatally just after take-off at Ahmedabad on 12 June.

It seems that one of the pilots selected these switches from “Run” to “Cut Off”, stopping the engines at a critical point just after the aircraft became airborne. The purpose of this article is to examine the arguments for and against deliberate action (compared with unintentional error) on the part of one of the Air India pilots.

On 11 July the Indian Air Accident Investigation Bureau published its preliminary factual report on Air India Flight AI171, a Boeing 787-8 registration VT-ANB. This has revealed the movement of the fuel control switches (FCS) mentioned above, and the resulting consequences of that movement. The data confirming this was derived from the two Enhanced Airborne Flight Recorders (EAFR) in the accident aircraft.

There are two FCSs, one for each engine in a 787. They have two settings: Cut Off and Run. The first act by any crew in starting a 787’s engines on the ground is to set the switches to Run. On the ground or in the air, setting the switches to Cut Off stops the fuel flow to the engines. (See photograph below, showing the switches just behind and below the engine power levers)

According to the AAIB report, just after take-off at Ahmedabad, these switches were moved from Run (up position) to Cut Off (down position). The left switch was moved first then, one second later, the right switch. This action cut off the fuel flow to both engines. There is no automatic function that could move these switches, so they must have been moved manually, or by something physically impacting them. Each switch has a locking mechanism so it cannot be moved accidentally, and there are guard brackets either side of the pair to deflect inadvertent contact by objects. To select the switches from one setting to the other, they must first be pulled out against a spring force to release a locking mechanism, then moved up or down.

Timeline (UTC):

08:07:37 VT-ANB begins take-off roll. 08:08:39 Lift-off at 155kt. 08:08:42 Max airspeed achieved 180kt, also No. 1 FCS switch was moved from Run to Cut Off, followed by the FCS for engine No. 2. 08:08:47 the Ram Air Turbine began supplying hydraulic power. 08:08:52 No 1 engine FCS moved from Cut Off to Run. 08:08:56 No 2 engine FCS moved from Cut Off to Run. 08:09:05 Mayday call transmitted. 08:09:11 EAFR recording stopped.

The report says: “In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff [sic]. The other pilot responded that he did not do so.” Each pilot is recorded on a separate channel, so the AAIB must know which pilot made each statement, but has decided not to release the information at this preliminary stage, The report confirms that the copilot was the pilot flying, the captain the pilot monitoring. So it seems that one of them, apparently, moved both FCS from Run to Cut Off (see Timeline above), and the other noticed him doing it. Then, about 10 seconds later, one of the pilots attempted to restart the engines by restoring both FCSs to Run.

The report explains the effect of restoring the FCSs to Run, first in 787s generally, then specifically what happened in this case: “When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The EGT [exhaust gas temperature in VT-ANB] was observed to be rising for both engines indicating relight. Engine 1’s core deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC.”

Take-off and early climb is a period of intense concentration by both pilots, the joint task being to ensure the aircraft maintains a steady climb while allowing the airspeed to increase gradually in a controlled way.

Under normal circumstances, after unstick there is only one actionable task for the pilots to carry out quickly: to check that a positive rate of climb is confirmed by the flight instruments, then select the undercarriage up. This task is normally carried out by the pilot monitoring on orders from the pilot flying, and it would entail moving the undercarriage control lever – located on the forward instrument panel – manually upward. In this case, according to the report, no-one called for the gear to be retracted, and no-one selected it up.

Instead, at about the time the gear would normally have been retracted, the FCS were moved downward from Run to Cut Off, the left switch first, the right switch a second later.

It is difficult to imagine that a crew member would have made such a gross error as reaching down and slightly back to move two small switches downward, one after the other, as a substitute action for a well established routine which would have involved reaching forward to move a single lever upward. And there was no cueing request from the pilot flying to pull the gear up anyway.

Pilots have occasionally, however, carried out inadvertent gross errors that almost defy credibility. You can see here the description of how, in January 2023, a Yeti Airlines ATR72 scheduled passenger flight was inadvertently set up for disaster during a visual circling approach to land at Pokhara airport, Nepal. I wrote that linked piece based on the preliminary report, but when the final report was published by the Nepal authorities it gave the following verdict: “The most probable cause of the accident is determined to be the inadvertent movement of both condition levers to the feathered position in flight, which resulted in feathering of both propellers and subsequent loss of thrust, leading to an aerodynamic stall and collision with terrain.” The check pilot had been asked by the pilot flying to increase the flap setting from 15deg to 30deg, but instead of moving the flap lever, he moved the pair of engine condition levers (picture supplied in linked article) to the position that demands the propellers to feather and stop turning.

If one of the pilots of AI171 did know what he was doing when he moved the FCS, he must have known that his action would have more or less guaranteed the result the world has witnessed, because there was insufficient time to restore usable power once it had been cut. VT-ANB was airborne only 3 seconds before the first FCS was switched to Cut Off, followed a second later by the second FCS, then ten seconds after that the FCS were both switched back to Run. The total airborne time was 42 seconds before colliding with the buildings that began break-up of the aircraft.

As for the likelihood that professional pilots would want to cause the destruction of the aeroplane they are flying, history provides evidence that it happens from time to time.

This was the summary of the situation as presented in the FlightGlobal annual safety review for calendar year 2023, which points out that deliberate acts by pilots to bring down airliners have been carried out by aircrew from all regions and cultures: “Pilot suicide on commercial flights in the last three decades has not involved only Europeans and North Americans. A Japanese, a Moroccan, an Egyptian, a Mozambican, a Botswanan, and a Singaporean, among others, have all been involved. The Flight Safety Foundation’s Aviation Safety Network accident database shows that, in its records beginning the 1950s, there has been a marked acceleration in the numbers of flights brought down by pilot suicide since the beginning of the 1990s, and this acceleration has continued in the new century. It is undoubtedly a modern flight safety hazard.” Since that time, although China has not confirmed it, the rest of the world has reason to believe that the March 2022 loss of a China Eastern Airlines Boeing 737 was not an accident.

It is inevitable that deliberate action by flight crew should be considered when a disaster like AI171 occurs. The India Air Accident Investigation Bureau will undoubtely investigate this possibility. But just one part of the trajedy is that, when all the flight crew die, their intentions will never be known for certain.

AI 171: the system is beginning to leak under pressure

David Learmount Uncategorized , , , , , , , , , , , , , , , , , , ,

Air India flight 171 crashed immediately after take-off from Ahmedabad on 12 June, and today, two weeks later, with no news about causes, the system is beginning to leak.

This is what happens naturally when information which people know is available to the authorities is withheld from the media and the public.

It’s easy for authorities like the Indian Directorate General of Civil Aviation to believe they can justify withholding information on the grounds that it’s very complicated, and they intend to release it quite soon anyway. Unfortunately for the DGCA, today’s media environment does not have that kind of patience any longer, especially in a case like this.

This fatal accident, a first for the Boeing 787 of any marque, killed 241 people on board and many on the ground. Whatever the cause was, it was highly unusual – maybe unique. For that reason, the industry and its regulators are desperate to know if there might be an unknown latent failure in the 787, so they can stop it happening again.

This pressure is what causes the system to leak. The Air India 171 flight data recorder has been downloaded by the National Transportation Safety Board for the DGCA at the Air Accident Investigation Bureau in Delhi, so some outstanding data will already be clear, even if not fully analysed yet.

Meanwhile the NTSB is sworn to secrecy according to the International Civil Aviation Organisation protocol which states that the nation in which the accident occured is responsible for the investigation. So in this case, the NTSB provides all its data to the DGCA, but as an agency of the nation in which the accident aircraft was designed, built and certificated, the NTSB has a particular responsibility to ensure that all operators of Boeing 787s throughout the world – there are about 1,000 of the type flying today – learn as fast as possible what, if anything, they should do.

That NTSB responsibility is a heavy one, but at the same time they want, if possible, to stick to the protocols to ensure the investigation proceeds calmly.

The NTSB obviously has to tell Boeing any details that are emerging. Then Boeing has an urgent duty to provide advice to 787 operators, particularly if any system failure detected might possibly repeat. This information will be received at Boeing by many engineers and technicians who must act rapidly to frame a plan for inspections and corrective action, then communicate with the operators, where an even larger group of airline technicians must carry out the Boeing advisories, or any directives that the Federal Aviation Administration may see fit to issue.

The pressure on the DGCA is of a different kind, and arguably less urgent. It is, after all, a regulator, a bureaucracy, with the responsibility to oversee the investigation and ensure it is conducted properly and according to law. It does, however, face the reality that a lot of highly relevant information is being shared right now by hundreds of experts all over the world, and the media knows it. So if the DGCA delays release of established facts, it will face increasing censure, especially if it delays release beyond one calendar month from the date of the accident.

A month is now firmly established as the time it should take for an air accident investigator to establish the basic facts of the case, and release a “preliminary factual report”. The final report can take more than a year.

Meanwhile, what of all those FDR facts whizzing around the world between experts at the manufacturer, the investigator, the world’s civil aviation authorities, and all the airlines that operate 787s? Well, they leak, of course, because they are important and everyone knows it. But most of the time the precise source of emerging information isn’t obvious, because individuals discussing them do not want to be recognised, so responsible journalists have to be careful what we do with what we hear.

What happens, however, is that it gradually becomes clear, among the plethora of opinions and guesswork always out there, which facts are beginning to establish themselves.

Some are simple, almost obvious. For example, the one emergency radio call made by the AI 171 crew said they had lost power, and an observation of the flight path almost immediately after unstick corroborates that puzzling fact.

But double engine failure immediately after take-off is almost unheard of, so what caused it? That is less obvious.

The DGCA has issued a list of checks it required Indian 787 operators to carry out. Unfortunately it lists checks that – mostly – are routine and would be carried out anyway.

The exception to that is the requirement to test the Electronic Engine Control System. These are computers called Full-Authority Digital Engine Controls (FADEC) that monitor the engines’ performance and react to demands by the pilots via the power levers or the flight control panel (autopilot input). These are vital, but have been established since the 1980s as highly dependable devices, and more reliable by far than the old mechanical connections.

So if both FADECs failed that would be extraordinary. In fact it makes more sense that something else failed or malfunctioned and disabled both FADECs. There is a lot of credible information gathering that backs this up, but since its precise source is not certain, I will not run it here.

Suffice to say we will soon learn what the problem was, because the DGCA knows it would look very bad to sit on it beyond 12 July 2025.

Enhanced checks for GEnx-powered Indian 787s

David Learmount Uncategorized , , , , ,

India’s Directorate General of Civil Aviation (DGCA) has issued orders for “enhanced checks” to be carried out on Boeing 787s powered by GEnx turbofans registered in the country.

Those looking for clues as to the causes the authorities believe might be behind the disastrous Air India 787 crash at Ahmedabad on 12 June are likely to be disappointed, because the checks cover a broad spectrum of systems and components, many of which would be checked before all flights as a matter of routine.

But here is the instruction anyway.

Air India suffers the first fatal crash involving a 787

David Learmount Uncategorized , , , , , , , , , , , ,

Boeing’s long-range widebody 787 has been in service since 2013, and had some worrying technical problems in early service. Those, however, were corrected and it had been crash-free until now.

There has been very little information for investigators to work with since the Air India 787-8 crashed just after take-off from Ahmedabad today.

There are reports of an urgent Mayday call from the crew during the brief airborne period. The 787 appears to have reached a maximum height of about 600ft before descending, wings-level, in a nose-high attitude, to impact with buildings about 1.5nm from the runway’s end. An explosion followed, resulting from the large amount of fuel on board contacting hot engine parts when the crash breached the fuel tanks. The aircraft had been fuelled for the scheduled ten-hour flight to London Gatwick.

Powered by twin GE Aerospace GEnx engines, the 787-8 took off from Ahmedabad at 13:40 local time in good weather, carrying 242 passengers and crew. Initial reports from the site indicate that all on board died except for a single passenger who was thrown clear, and has survived. There are expected to be many casualties on the ground, but the numbers are not known at present.

Looking at a video of the last few seconds of the flight, the landing gear still remains down, the flaps look as if they are still at a take-off setting – but the video quality is so poor that cannot be stated with certainty – and the aircraft is in a steady descent which only ended in impact with buildings and the ground.

At this point after take-off, the gear would normally have been retracted and the aircraft would have been climbing rapidly. The steady descent actually witnessed in the video suggests the crew could not command sufficient power from the engines to keep the aircraft level, let alone to climb.

If that is true, what had happened to deprive the pilots of power from the engines? Had they suffered a multiple birdstrike that damaged both engines? No-one so far has reported a flock of birds in the departure path.

And failure of a single engine should not cause a crew to lose control of a modern airliner, even in the critical early climb phase. The video shows an aircraft that looks under control, but unable to climb.

Simultaneous engine failures for unconnected reasons simply do not happen, according to the entire history of aviation accidents. So if there was a failure of both, what could have caused it?

Frankly, we don’t know for certain in this case if engine power was the problem, but if you go looking for a potential cause of multiple engine failure, fuel contamination could do it. Again, however, history is against that potential cause in observed reality.

Could the pilots not demand the nose-up attitude they actually wanted because of some technical limitation? Well, that happened in the notorious 737 Max cases, but there is virtually no commonality in the way the 737 Series controls work and the manner in which the 787 Series operates.

So we have to wait for the investigators to report. These days, if the Indian investigators follow today’s recommended protocol, after about a month they will provide factual data of which they are certain, even if the final verdict is not yet clear. The aircraft’s “black boxes” – the cockpit voice recorder and flight data recorder – will provide data on what the aircraft actually did, and may throw some light on why it did it.

Meanwhile, be patient. This kind of accident is incredibly rare these days, and finding the truth behind it could not be more important.