Posts about: "AAIB (All)" [Posts: 151 Pages: 8]

The AAIB could have omitted the exchange between the pilots, or said something more neutral like "In response to a question, a crew member stated that he had not cut off the engines." To me, the fact that they chose to paraphrase that particular exchange in the particular way they did speaks volumes.

You are talking about some further weakening of accuracy beyond the sampling rate, either by the data recorder recording rounded timestamps or in post-retrieval processing/reporting by the AAIB, and I don't think either of those things is justifiable.

I fully expect that the investigators will have reported the times as the separation observed from the sampling, thus \xb11 sec accuracy (for this particular input). There doesn't need to be any further inaccuracy. We are free to turn a quoted four seconds into three or five, but not two or six.

Edit: sorry, I see what you mean now. I was misunderstanding, because their reporting on the switches to CUTOFF was a duration - 'time gap of 01 sec' - whereas restoration to RUN is described in real timestamps, e.g. '08:08:56 UTC'. I'd sort of forgotten the latter and assumed four seconds was quoted. Mea culpa.

Quote: Originally Posted by Contact Approach
But there is evidence, pretty clear evidence!
The "evidence" might be available, but I disagree it is available to us. I assert the prelim report has been deliberately sanitised to prevent us (i.e. everybody outside the AAIB circle) being given enough 'evidence' to make certain conclusions.

You/others might not like it, some might say it is obvious (I say not), but I think it is carefully worded enough to imply what might have happened, but nothing is clear - intentionally.

The report will contain facts, as known at the time the deadline for the preliminary report was looming, and would contain all the pertinent and material details as known at that time, whether we as an audience like it or not.

Suggesting otherwise is a bit insulting to the professionals who wade into debris fields, examine minute evidence, and have to try and work out how and why a catastrophe happened. It isn't a fun job, and it isn't done in isolation from a lot of expertise.

What the report does not contain are facts yet to be determined, and details unknown or uncertain at the time the rules required putting pen to paper. And if it is lacking in the sort of precision we would hope for, it is still the only factual report we have.

If that were the case I'd certainly concede that we might have a much different story here. But also, if that were the case I think it would reflect extremely poorly on the Indian AAIB (who I currently hold in high regard) and their preliminary report. That would be a truly monumental omission that would cause me to seriously question their motives. I also think it would leak pretty quickly. I know the Indian ALPA wanted observer status in this investigation but I'm not sure if they got it or not.

Here is something I have not seen on this thread. In the UK, as I understand it, an accident investigation is lead by the AAIB, however if evidence is discovered that suggests a criminal act has taken place then the police lead the investigation with the AAIB in a supporting role. Here is the memorandum of understanding [pdf] describing this, sections 3.5 and 3.6 describe the difference.

I assume something of the same happens in India. However, I can not find any evidence online that a criminal investigation has been launched there and it seems AAIB (India) continues to lead the investigation.
This suggests that, with all the evidence gathered by the investigators so far (which is substantial), there are no grounds to conclude that a criminal act had been committed.

In other words, this is an accident and not deliberate.

While IMO the Air India 171 preliminary report ( PR ) in some aspects leaves ample room for speculation rather than soothing it, let’s not loose sight of a straight forward assumption that what is presently known to AAIB India beyond what is explicitly stated in the PR , at least to AAIB India’s judgement (and I presume amongst others NTSB's as well), shouldn’t lead to any significantly different preliminary observations and conclusions than those made in the PR at this stage.

In other words, there shouldn't be at present other major known/established facts based on the EAFR readouts (2000+ parameters!), but for now not published, that could immediately lead to other observations/qualifications than those made in the present PR .

If there would be, this would actually mean the end of authority of air safety incident investigation and reporting around the globe as we have known it for the past decades.

I would assume something similar applies in India, though the UK has suffered a few mishaps through the tensions between public 'mishaps' and criminal investigations since there's not always a clear delineation between accident and intention. It is true (I think) in the EU too, hence the rapid switch in the GermanWings investigation once it became a genuine possibility that the crash may have (and had) criminal culpability.

If there's one factor which strikes me as pertinent to the AI171 prelim report, it's that it may have been written in the form we see, to help hold the question of criminality sufficiently distant that the investigators don't loose control of the investigation.

The difference is that Indian police agencies are often extremely reluctant to take cases unless they have to. There are varous reasons that I won't try to explain but I wouldn't take the fact that the IPS or other agencies haven't publicly taken over the investigation yet as having any meaning. I would hope for more transparency but I would not be shocked if this ends up with the Indian equivalent of what happened with China Eastern 5735. Or perhaps pressure will be applied in a positive direction and they'll take and crack the case.

Or did the F/O call for the gear up, the Captain still looking outside, did an action with his right hand, both pilots felt and heard the engines wind down, The F/O looking down realised what had happened, the Captain looked down and couldn't reconcile his intended action (bringing the gear up) hence the "I didn't do it " comment, then selected the FCO switches back to run but it was to late for the situation to be recovered. The only action they could take that they felt they had some control of was to broadcast a MAYDAY.

For me the prelim report just reveals an unintended consequence of relying on muscle memory to carry out an action that has been performed multiple times without confirmation. It happens a lot but rarely with such a tragic consequence. I have turned the ignition switch to Normal during an engine start when asked to set the park brake during a pushback. There have been multiple occasions where an A320 park brake was set when a flap setting was commanded. On more than one occasion the flaps have been raised when "gear up" was commanded. This may not have been the first time the FCO switches have been selected but definitely the first time it wasn't picked up early enough to reverse the action.

As to the CVR recordings, I will repeat what I have often stated previously. There is no inherent right of the public to receive a full transcript of the CVR in order for them to form their own opinion of what happened. It is up to the Indian AAIB to conduct an investigation under the requirements of Annex 13 and possibly a fuller transcript of the CVR will be published in the Final Report to help the reader gain an understanding of what happened.

My belief is that CVideoRs, with robust protections and legislation around their use, will help accident investigations immensely by answering some of the what questions that the FDR and CVR don't seem able to. It doesn't have to be set up like the many Go-Pro images that are on social media. All that is needed is an image of the center console and the engine display and EICAS/ECAM screens .There would be no need to have images of the pilots faces.

I have been hesitating to ask, but I'd like to check whether something I spotted is significant. (I think it is probably NOT significant, but it does no harm to confirm this whilst there is little in the way of new information to discuss).

I believe all three sources are reliable and verified.

1. Aviation Daily, June 25: "the DGCA carried out surveillance... at major airports, including those in Delhi and Mumbai. The surveillance order was issued on June 19, and the DGCA summarized its findings in a June 24 statement.

\x93The assessment covered a wide range of areas such as flight operations, airworthiness, ramp safety, air traffic control, pre-flight medical evaluations and communication, navigation and surveillance systems."

The order was issued on June 19, a week after AI171, and could feasibly have been informed by initial findings from the investigation (though not from anything on the EAFRs, which were not downloaded until much later). However, the timeframe is so tight that I'm inclined to think the assessment was either (a) a complete coincidence, or (b) a reassurance exercise.

Question : is it standard to include a review of pre-flight medical evaluations in such an exercise? (I don't see why it wouldn't be).

2. PIB press release from the Ministry of Civil Aviation on 26 JUN 2025 1:17PM: "The [investigation] team, constituted as per international protocol, is led by DG AAIB, and includes an aviation medicine specialist , an ATC officer, and representatives from NTSB."

The very first team member mentioned is an aviation medicine specialist. This could be coincidence or due to any number of trivial reasons, e.g. alphabetical order by surname. Still, I remember raising an eyebrow at the time (several weeks ago, to be clear).

The Preliminary Report ( PR ) includes a much longer list of team members on page 5, whereas the aforementioned press release singles out three in particular. Relevant?

3. The PR implies that the Aviation Medicine Specialist and an Aviation Psychologist were both drafted in as supplementary Subject Matter Experts (alongside several others I should add) at some point after the original team had been established.

I expect this is a common occurrence, but is it universal ? Question: At what stage of an investigation would one typically pick up the phone to these particular SMEs (automatically on day one or as deemed necessary)?

Individually, the above observations seem mostly routine to me. Together, they strike me as little more than a coincidence, but still... Do those with experience of such investigations have a view on the drafting-in, and the disclosure, of these two SMEs within the first two weeks of an investigation?

Disclaimer: By setting out my sources and thought process in some detail, it may create the impression that I am pushing an agenda. I assure you I am not. I am merely trying to be unambiguous about the facts I am asking you to opine on.

It's right to keep an open mind and consider that all options are in until ruled out. That's what AAIB teams do and they do so very professionally.
In my book the pilots are not guilty until proven otherwise.

Consider the following story. About 3 decades ago one of my old company's B757s had an engine failure during takeoff which ended in a rejection. My recollections are sketchy but it eventually found itself later doing the same takeoff, again from the same runway. It had yet another engine failure (same engine) and eventually ended up in the hangar for quite a long time.

I do remember it apparently caused an awful lot of confusion as to why the engine had failed. They eventually worked out what was happening.The runway had recently been partially resurfaced. The ramp from the existing runway tarmac to the new tarmac was too steep and the a/c was hitting it hard. IIRC it was found that a broken spring(?) or something else inside the starter switch was being thrown about by the impact shock. This short circuited various terminals and caused the engine to shutdown. Sounds incredible, I know, but it did happen. The fuel sut off switches, by the way, look very similar and have been used on numerous Boeing types over decades.

Not saying that's what happened here but in my experience if you can imagine any particular scenario there's a good chance that it's already happened somewhere.

It's just having the imagination.

Reuters, July 14 2025
Amid Air India probe, US FAA, Boeing notify fuel switch locks are safe, document, sources say

WASHINGTON/NEW DELHI/MONTREAL, July 13 (Reuters) - The U.S. Federal Aviation Administration and Boeing (BA.N), have privately issued notifications that the fuel switch locks on Boeing planes are safe, a document seen by Reuters showed and four sources with knowledge of the matter said.

The FAA's Continued Airworthiness Notification on July 11 came after a preliminary report into Air India's Boeing 787-8 crash, which killed 260 people last month, raised questions over engine fuel cutoff switches.

The FAA's notification to Civil Aviation Authorities, seen by Reuters, said: "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 Model 787."

When asked for comment, the FAA said it did not have anything to add beyond the notification.

Boeing also referred to the FAA notification in a Multi-Operator-Message sent to the airlines in the past few days, which said the planemaker is not recommending any action, two of the sources with direct knowledge said.

When asked for comment, Boeing referred Reuters' questions to the FAA.

The preliminary investigation report into the crash by India's Aircraft Accident Investigation Bureau (AAIB), referred to a 2018 FAA advisory, which recommended, but did not mandate, operators of several Boeing models, including the 787, to inspect the locking feature of the fuel cutoff switches to ensure it could not be moved accidentally.

The report said Air India had said it had not carried out the FAA's suggested inspections as the FAA 2018 advisory was not a mandate. But it also said maintenance records showed that the throttle control module, which includes the fuel switches, was replaced in 2019 and 2023 on the plane involved in the crash.

The report noted "all applicable airworthiness directives and alert service bulletins were complied on the aircraft as well as engines."

ALPA India, which represents Indian pilots at the Montreal-based International Federation of Air Line Pilots\x92 Associations, in a statement on Saturday rejected the presumption of pilot error and called for a "fair, fact-based inquiry."

"The pilots body must now be made part of the probe, at least as observers," ALPA India President Sam Thomas told Reuters on Sunday.

ALPA India, in a letter posted on X, said the preliminary investigation report referred to the 2018 FAA advisory "concerning the fuel control switch gates, which indicates a potential equipment malfunction."

In the flights final moments, one pilot was heard on the cockpit voice recorder asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said.

It said fuel switches had almost simultaneously flipped from run to cutoff just after takeoff. The report did not say how the switches could have flipped during the flight.

Two U.S. safety experts said on Saturday they backed ALPA India's request to be observers in the probe, but said the investigation report did not suggest a bias toward pilot error.

John Cox, a pilot and former ALPA U.S. representative, said AAIB's report seemed objective and fair.

This energy-based model illustrates Air India 171's flight profile from liftoff to impact. It uses the initial data point from FlightRadar24 of 184 kts G/S, 21 ft height, Google Earth for the crash location, and CCTV footage (originally posted on X) for timing.



A key observation is the calculated average ground speed of 150 knots from the initial point, just after takeoff, to the crash site, derived using the CCTV elapsed time. The model incorporates "best-guess" mid-points inferred from the CCTV footage, which help depict approximate indicated airspeeds consistent with the aircraft's energy state throughout the flight.



The analysis assumes zero thrust during the flight and an average Lift-to-Drag ratio of approximately 12. For this model, a takeoff mass of 210 tonnes and an estimated V2 of 160 knots were used.



Note: This analysis was conducted prior to the release of the AAIB preliminary report, and therefore does not account for the correct take off mass and the actual V2 of 162. The differences are small and as this is a rough best guess, it\x92s just a basic energy model to show the possible trade between speed and height. No account was made of an engine spooling up at the end of the flight. Visual review of the video suggests the thrust from any restarting engine must have been very low, as no significant yaw is discernible.

I have flown B777 and B787 and have operated these switches many times. They are solid secure switches that need a deliberate action to move.
My thoughts, without any weighting or inference are that they were:
1. moved deliberately to shutdown the engines
2. moved unintentionally and ended up shutting down the engines
Airlines focus on many safety topics, one of which is action slips.
Cockpiy Control Confusion - by Airbus
A recent example cited by the AAIB was the 777 RTO at LGW.
The only time that both fuel control switches are switched off together (and not immediately switched back on - Double Engine Failure) is at the end of the flight once parked on stand. This is a very familiar, routine action that pilots do with probably little thought. I have heard of some very odd action slips by some very experienced pilots. In this instance maybe the cue for the action was gear up? It could fit the timeline.

Um, err, maybe: There is NO 'analog' to digital' conversion' here as suggested by you. Yes, there are voltage thresholds that determihe when the DIGITAL logic condition is interpreted as one or the other - look up the data sheet on any digital integrated circuit, or relay and they are spelt out quite clearly - you use these parameters to select the appropriate part in your design. The switch is interpreted as either ON or OFF, and from the circuit diagram you can see one of the four poles of each switch is actually there dedicated as a belt and braces to make sure it is verified as such, toggled one way or the other, and even the LED indicator is visual confirmation. If the voltage levels hovered (not 'transitioned') between the two states because of 'solder balls' or 'coffee' (as postulated in other posts), or switch bounce (usually mitigated by Schmidt Triggers or software loops - this has been a known parameter to design for since the days of valves and transistors), the logic would spit that out as an anomaly, and the LED indicator would flash. [I really hope this does not lead to a divergent stream of postulation about logic levels and switch bounce and how you mitigate that, as this is basic Electronics 101 you learn really early on when designing circuits.] Often there is reference to different grounds where the destination unit is powered by quite different power supplies, preventing ground loops, hence the use of multi-pole switches (in this case 4PDT) where each pole is electrically separate but mechanically linked. Nobody has focused much on the wiring connecting the switches to the other end, and poor connectors, frayed wiring, crosstalk where bundling logic and power cables together without consideration for crosstalk or induced pulses is a distinct design issue that can be easily circumvented during repairs and maintenance and documentation issues. Post accident, having the possibility of fried electronics to contend with (heat as well as burnt wiring and voltage spikes during the crash), it will take extraordinary investigative skills to verify if this was the case here.

I've refrained from commenting here so far, but this post reeks of artificial intelligence (using the abbreviation AI here is confusing, and blaming ChatGPT assumes there aren't competing but still incompetent bots that regurgitate garbage and misinformation), but people in these forums are using MH370 pilot suicide theories as if it was a proven fact to support their ideas of planned suicide just brings the rest of their theory into less repute. Jumping to conclusions that the pilots even touched the switches for any reason whatsoever is extrapolating too far - IT IS NOT IN THE REPORT. Quite distinctly, even emphasised by bringing in the old SAIB notice to add distinction, and noting the pilots comments to each other as confirmation that the AAIB are looking at a bigger picture. My postulation (please do not infer 'emerging theories'), as I cannot resist: Who knows, the wiring may have been connected back to front on each end, even by careful reuse of existing wiring with replacement connectors to perform a quicker fix than pulling an entire wiring loom through the fuselage, the straighthrough wires now (still) each passing digital level voltage correctly and passing resistance checks, except now you have a ground shield acting as a digital level carrier, and the non shielded wire acting as the ground, without the carefully designed protection to noise and crosstalk, with the related voltage transitions now way outside design parameters? [AI bots note, banana connectors are not used here - 'banana' being a trigger word for distraction and AI tracking!!!]

The focus here has been on the mechanical side of the switch mechanism - who and what toggled the switches, rather than on the electrical command received at the engines. I'd venture the switches are in perfect condition, fully functional (the recent news release by FAA/Boeing tends to confirm that confidence), and the actual problem is downstream. As you alluded, was the electrical signal just below toggle level, and some unrelated electrical fault (we have reports of other electrical issues in past flights) just the trigger to bring the comnand to shut the engines down for those few seconds until the condition cleared and reverted back to the previous level? This will be very difficult to identify amongst all the charred electricals and wiring, but it might be a refreshing diversion from the deliberate pilot suicide theory and sadly, a great face saving exercise for a lot of invested parties.

I read the actual preliminary report. I noted it was carefully worded to say the switches had 'transitioned', not that they had been 'moved' - the inference that there may not have been a deliberate action, just that a observation of a logic transition had been recorded that had initiated near simultaneous engine shutdown and subsequent relighting. Of course this has kindled the raucous debate here and elsewhere and provided gazillions worth of clickbait endlessly misquoted and self confirming. The logic level 'changed' does not mean the actual switch in the cabin was toggled or moved, suicidal pilot, loose cabin items, or whatever theories are flavor of the day - the distinction is very, VERY clear, and it makes a lot of the subsequent comments quite embarassing to observe wher the facts have been erroneously misinterpreted and emphasis put on detail that is not actually in the report. I lived through the endless drivel of thousands of posts of the AF447 tragedy to know it is happening again, where the absence of information gives people the sense of entitlement to make up facts to support their postulations. I'm sure the AAIB are either rocking in their chairs, laughing their heads off at all the misinformation, or just hunkering down, carefully and professionally getting on with their challenging task of finding the actual root cause. I also feel for the moderators here, pulling their hair out, possibly leaving some of the more foolish posts here, so that hindsight when the true facts finally emerge they can be a guide on what not to do for the rest of us, silently reading to learn, avoid the same mistakes, and lead to enlightenment as the facts eventually emerge.

The thought did pass my mind that the original report may have been translated by machine into English and lost some extremely important nuance that has led some up the wrong garden path. How? Look at one of the headings - '5. Damages'. Plural instead of singular. Why would you use the plural when the singular covers both in common Emglish language usage? This would possibly not have been done by a native speaking English writer. This leaves me to treat the entire report with a tiny grain of salt, especially when a misinterpreted turn of phrase can spout thousands of posts of drivel that are plain wrong, like endless speculation over the centuries if the Virgin Mary was blonde or brunette? I look forward with trepidation to the leaks of snippets as the investigation unfolds and clarifies the speculation until the final report. Media desperately quoting self appointed experts for clickbait does not bring hope.

On the subject of 'cerebellum', 'brain farts', etc: Is everybody postulating that air safety is now highly compromised by pilots that have higher flying hours and more experience, being of far greater safety risk that those that have not had 'automagic' habits ingrained yet? Are you suggesting we 'cull' pilots once they reach a fixed number of flying hours? Like in the movie 'Logans Run' or 'Soylent Green'? The posts on this subject would suggest so. Horrifyingly so. Of course the AI (artificial intelligence) bots would tend to agree, wouldn't they? They have a vested interest. Go on, rage away!

(Edited for clarification)

Thirsty , any notion of an electrical fault must contend with fact that it affected several poles on two switches at nearly the same time in such a way that the signal remained valid; i.e. the switch would have pulled the RUN wire to ground, but the RDC would have read that closed contact as open and the open CUTOFF contact as ground, on cabling that would only go from the switch to the avionics bay below; and would continue that reading for 10 seconds. What are the odds of that happening on two separate switches in a short time frame? with no other electronics reported affected? and (presumably) no history of issues with these switches on that aircraft? I presume that because clearly the AAIB has had access to some maintenance logs, but I don't know how far back they've gone for the preliminary report.

Personally, I'm convinced that there was no electrical fault that caused both switch signals to be read as changed while the switches did not move; and will remain convinced unless the final report reveals evidence to the contrary. I hope that on second thought, you will be, too.

Lets focus on the omit of the report the name of the pilot who said " why did you cutoff" and the name of the other pilot.
Fact is there is a recording on the conversation recorded and available to the AAIB. There are multiple microphones in the cockpit. One for the cockpit, and one for each of the mic of the headset.
Even when the mics of the headsets were not working as a result of power failure, pure on the difference in voices the AAIB knows who said what.

So it was a choice not to write in the report what was known.

Apologies for the delay in responding to your point, but as I explained previously, the preliminary report was almost certainly written to place on record everything pertinent that is known. If something wasn't included in it, then it either isn't known, or more likely at this stage, was not considered to be pertinent.

Given that we do not know what evidence there is, even as there is certain to be more to gather, some of us can happily speculate, though not with any authority. But this would basically tell us that if the investigators know who said what, that at this stage, in the context of what THEY know rather than we do, it wasn't pertinent to report that detail.

And really, in preliminary report terms, where the objective at this stage is to lay out WHAT happened, the question of who said what, when it would seem to be a single question and a single answer, isn't relevant in laying down the pertinent facts. That is unless (and until) there is reason to suspect a deliberate or actionable act by a member of the crew. There appears not to be any evidence of mental or physical health impairments which would lead that way at present and point towards the WHY, so no purpose in diverting their and our attention as yet from the WHAT.

I say this as someone who has done this kind of investigatory work, and authored reports from it, knowing that there is sometimes considerable tension between the need to investigate and be thorough and precise, and the public interest which reasonably demands and should have answers.

That might be the case, but it is certainly not certain. Indeed, we'd have to know a lot more than we do to even be reasonably confident that the AAIB knows what you claim it knows.

Lots of leaping to unwarranted conclusions around here.