Posts about: "Preliminary Report" [Posts: 301 Page: 15 of 16]¶

Yes.

We have the preliminary. Lets hope the investigation people get the time and piece needed to produce a high quality report.

For that TV show I guess most people reading this thread will get no new facts.
For the speculation part I guess it is a higher risk of us sighing than hearing any news.

I think you make an assumption in your last sentence, which is one that I do not make based on the inputs provided.

This strikes me as one of the most apposite of questions in this incident.

If we take it as read - which I do but some clearly don't - that the preliminary report contains all the pertinent details as known at the time it was written, then that delay is rather inexplicable. The absence of any reported further confrontation or verbal exchanges on the flight deck rather suggests the pilots were not sure what had happened.

Even if it is taken as read that one pilot was acting intentionally, unless their hand covered the switches - in which case surely there would be some audible action or demand by the other - it would not likely take that long to act and correct the problem.

And that did relight the engines, as the preliminary report notes.

Just FYI: Air India crash aftermath handled 'irresponsibly', says court

Stil a better job than the one on Ch5 here. I had some input to the one you refer to but so did others and not all the stuff that was relevant made it to the screen unfortunately. The methodology behind the cuttoff switch design, confirmed by tdracer, was provided but not used. Obviously there was nothing new since the prelim report anyway, so nothing new for them to work with.

That's not what it was about.

From the Reuters article: So the question was: did the preliminary report blame the Captain?
I agree with the judge that it did not.

It's a father who wants a court to tell everyone that his son did nothing wrong.
It's understandable, but I'd rather wait for the facts to emerge.

But given this legal climate, I fear the AAIB might withhold the final report, as they're likely to get sued over it if they publish.

Is it your understanding that "The Federal" (whom The Financial Express cites as a source, and from whom msn grabbed this article) is privy to information that the Investigating Team does not have access to? While it is possible that there are some leaks from within Air India that someone may be using as a source, the link you offered is third hand.

Treat with caution.

If you read the preliminary report, which is linked to here on PPRuNe, in post number 3 of this very thread (you can download .the pdf file), you will find that the investigation board had reviewed the maintenance records and didn't find anything that they felt was a contributor to the accident in the way implied by the article you cited.
With that said, the investigation isn't completed (the final report isn't due out until a year after the crash) and they may uncover all kinds of details that were not reported upon within the body of the interim report.
But, you may also wish to consider that if something does crop up that is worthy of the attention of all 787 operators, they will issue either a bulletin (or other such amplification from the interim report) via formal channels in order alert those whose fleets have that aircraft in them.

I note a lack of reference to any such official information in the article you linked to.
https://www.msn.com/en-in/news/india...id=socialshare

I was taught that when you insert blame into the process safety suffers. I can't imagine Safety Culture is taught differently today. Sadly it seems many are out to do just that in the case of this investigation. This will be a watershed moment for Indian aviation safety and probably set the tone for decades to come. Let's hope that they manage to pull it off, despite the adversity. As far as I can tell there is no more current information than the previously discussed preliminary report?

A week ago the BBC reported that 2025 was the sunniest year for the UK since records began; back in August I was diagnosed with a small spot of non-aggressive skin cancer, it is probably not a coincidence! This led me to think - could the Air India 171 crash be due to solar radiation? I searched the preliminary report and (disappointingly) found no reference to it, so I dug a bit deeper, as you do. According to Airbus, data corruption due to radiation was the underlying cause of the incident on A320 flight 1230, but fortuitously had a very different outcome to the Boeing 787 on flight AI 171.

However, comparing the two incidents some interesting common factors come out:-

1. Both incidents were at similar latitudes, the Boeing 787 was near Ahmedabad, which is at 23 deg N; the A320 was near Tampa, which is about 28 deg N. The Tropic of Cancer is at 23.4 deg N, where the sun will be directly overhead on June 21st. The significance of this is that the Boeing 787 is more likely to suffer data corruption due to solar radiation on 12th June, than the A320 on 30th October.

2. Both incidents were at a similar time of day, a few hours after local noon

3. Airbus seem to have good evidence that the flight 1230 incident was caused by a solar flare corruption. From the BBC /news/live/cvg4y6g74ert:- " It’s thought the incident was caused by interference from intense solar radiation, which corrupted data in a computer which controls the aircraft's elevation ". Airbus identified the problem that was the cause of the uncommanded change to flight control and rapidly come up with a solution which only required reverting back to an earlier software issue, i.e. they already had software that could cope with such data corruption.

4. Boeing have not identified any aircraft fault as the cause of the 787 crash. And sadly, as has happened before, the air-crew are being looked upon as possible scapegoats. Airbus have identified solar radiation as having caused data corruption, it would seem to be highly plausible that Air India 171, with higher intensity of solar radiation, could well have suffered such data corruption.

5. The different end results are consistent with data corruption, but within different systems on the two aircraft.

It would be interesting to see if any other aircraft's 'uncommanded' events happened when the aircraft was in the tropics, at around noon. A possible candidate is the Boeing 777, flight SIA321 on 21.5.2024. From wiki 'Singapore_Airlines_Flight_321':-

At 07:49:40 UTC the aircraft experienced a drop in vertical acceleration from +1.35G to -1.5G within 0.6 seconds, which likely caused unrestrained passengers to become airborne. At 07:49:41 UTC the vertical acceleration changed from -1.5G to +1.5G in 4 seconds, which would have caused airborne occupants to fall . The aircraft would have been flying over Myanmar, at a latitude of about 16.5 deg N; the local time for 07:50 UTC would be 14:20, close to local midday. This means the Sun would have been high in the sky and so radiation intensity would be very high.

Over the years I have worked on the software for several aircraft systems, starting in 1971 as a Software Engineer on Tornado and ending in 2009 as a Software Safety Assessor on Typhoon, including projects on Harrier, A320 and ESA's ISS, where solar corruption is taken very seriously. I would expect ELAC software to be cyclic, running at about 50Hz, with data smoothing software to remove spikes. A random memory corruption could cause a spike in a critical parameter (such as 'Last Value of Elevator Angle' ), leading to a large spike in elevator demand angle. This would explain the data from the SIA321 incident, where there is an initial rapid change to vertical acceleration in 0.6 secs (smoothing bypassed), followed by the pilots' smoothed recovery in 4 secs.

In contrast, on flight AI171 I would expect the software that determines and sets the true/false state of WoW in RAM (probably the Landing Gear System) would only be active at take-off and touch-down, or perhaps only when the landing gear doors are open. However, if the state of WoW is corrupted outside of this period and goes from 'false' to 'true' (a "bit flip"), WoW status will stay at 'true' until the aircraft lands again. As there is a serious aircraft safety hazard with high engine power whilst on the ground, the thrust-control malfunction accommodation (TCMA) system will reduce power to just enough for Taxiing. If this is what happened on AI771, it is most likely that no matter what the aircrew did, they would not be able to get the engine power back up because WoW would be stuck at 'true' and TCMA would hold it down.

I don't know where you read that but it's wrong.
The preliminary report as quoted above states that the fuel cut off switches were set to off. Some seconds later, the report goes on to say, the switches were returned to the on positions.
The engines reacted to the switch positions, the switches were not moved as a reaction to the engines doing something they shouldn't.
This TCMA red herring is becoming tiresome.
Please stop and wait for the final report.

The preliminary report explicitly states that the crew did manage to restart one engine. Please do read the preliminary report, it is the best source we have, and any question you might have regarding what it says are on topic here. TCMA is not mentioned because none of the conditions it needs to trigger were part of the accident sequence (it's more than WoW).

There is absolutely nothing ambiguous about the statement "switches t ransitioned to CutOff". The preliminary report reports the facts as currently known about the investigation - any ambiguity in the report is in areas that require conclusions - not facts (e.g. why the switches moved, or who moved them).
When you need invent stuff (or new meanings) for your hypothesis to work, it's time come up with a new hypothesis...

Non-paywalled version: https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:

whilst intentional action is the most obvious explanation one can\x92t ignore data and technical grounds if one is also going to dismiss counter theories on technical grounds

I still don\x92t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it\x92s 1s then the \x91debunking\x92 by saying it can be done very quickly is moot as (near) instant would record as 1s I believe

and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential

it\x92s easy to dismiss these narratives as vested interests but let\x92s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed

in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views

"The aft EAFR burned before the crash" was I believe originally an attempt to tie it to the aft battery fires the 787 had more than a decade ago, as they're both 'aft'. Never mind that the aft electronics bay (APU battery) is under the floor near the wheel well while the aft EAFR is above the ceiling near the rear doors.

It's one second intervals but not necessarily recorded simultaneously. The NTSB has a few FDR reports from previous 787s that should show roughly what you would expect. I don't see any discrepancy.

RAT out would be recorded on the EAFR I believe, they just haven't explicitly specified when it happened.

The engines ran down after the switches were recorded moving. Even if the RAT deployed, that does not suggest that the crew switched the engines off because of an engine failure.

No crew is going to shut down the engines down simply because a RAT deploys unexpectedly.

It is very, very, very hard to argue that the EAFR records valid data for A/B/C/D but generates fake data for X/Y/Z, but the fake data is still externally and internally consistent. Which seems to be where we are now.

I don't think you can or will effectively prove whether it was intentional or some kind of an action slip, and by which pilot.

I think the accident report will be able to very clearly and with no reasonable doubt show that the switches were physically moved.

From the article:
And there you have the answer. If you refuse to consider the scary option, whatever remains must be the 'truth'.

Have we had actual confirmation that the aft EAFR was completely unrecoverable? I don't believe so; the preliminary report said this:
The forward EAFR will have shown when each bus lost power and if they don't believe there's any unique data on the aft EAFR, attempting to recover data from it is basically an academic exercise.

All of this is factually incorrect.

It's incorrect to say we're blaming the pilots; the prevailing opinion seems to be that ONE pilot (but we don't know who) inadvertantly flipped the switches in lieu of another task ("action slip").
It's incorrect to call this "mass murder", and I don't think anyone did (and stayed unmoderated).
It's also incorrect to say there's no smoking gun: the preliminary report is very clear that the fuel cutoff switches transitioned, i.e. somebody moved them such that one set of contacts was registered by the electronics and the FDR, and another set of contacts operated the fuel valve. The whole accident sequence follows from this logically and without contradictions.

It is clear that MH370 deviated off course intentionally, but we cannot say if a pilot planned this, or if the aircraft was hijacked.

It is false to say that the pilots were blamed "instantly" for the 1994 Chinook crash; the RAF board of inquiry did not do that. That ruling was overturned at first, but two subsequent inquiries re-overturned that, so that the pilots stand exonorated today.

Please do review the facts.

I don't think we have any real evidence for intentional vs action slip. From what I've seen, the moderation has been light since the preliminary report came out showing the cutoff switches were used.

From what I've seen here, the consensus is somewhere around 70% intentional 30% action slip.

I agree that we're unlikely to ever know; several of the discussions around cockpit video recorders were kicked off by that.

This post might help clear up your confusion: Preliminary Report Timeline

Let's remember that totally independent of the external pull the toggle to unlock mechanism, internally, the switch still has the original over center mechanism which will spring the switch and contact to one extreme, or the other. Irrespective of the secondary locking feature, all quality toggle switches will spring to the intended position to prevent the switch contacts from resting just or just short of contact, and possibly arching internally.

Yes, if defective, the pull part of the toggle can rotate, and then the motion of the toggle will be abnormal. This would be entirely detectable in the moment by a pilot familiar with the operation of the switch. I see one of three situations here: The switch would operate properly, and the report is not accurate, the switch was operable, but the locking part of the toggle was not moving correctly (so the switch was defective), ans someone was satisfied that once positioned to run, it would remain there safely (suitably qualified mechanic, I hope, or the switch was entirely defective, so the flight could not depart until the switch was replaced. All three of these conditions are very easy for the pilots to understand. One does not require maintenance activity.

All of that said, I see this as peripheral at best to the Air India 171 crash. The preliminary report tells of both fuel cut off switches being found in the run position, and states that they were both moved from run to cutoff after takeoff within a second or so of each other, and then back to run. Nothing authoritative I have read so far from the Air India 171 crash suggests that either one of the fuel cutoff switches were defective. Indeed, the events of the accident suggest that when operated, they functioned exactly as intended! Their being found in the run position removes doubt that they (the locking feature) were operating properly. I think that the report of today, if credible, is unrelated to the 171 crash in causal information.