Posts about: "CVR" [Posts: 256 Pages: 13]

I guess with current information it\x92s going to be hard to rule this out. Once they fully analyse the CVR, I think we\x92ll know the answer to this. If the FO is asking the question, it\x92ll be more likely that this isn\x92t the case.

The switches were operated at 3s after liftoff\x85exactly the time positive rate would be confirmed\x85so I\x92m still thinking third party isn\x92t the most likely scenario.

FARs require that the CVR be "operated continuously from the start of the use of the checklist (before starting engines for the purpose of flight), to completion of the final checklist at the termination of the flight".

Yes, and on the 737 and 320, there is a dedicated switch to turn it on before engine start when it starts automatically. I\x92m sure the 787 is similar.

Don\x92t think there is. I can only think of CVR test and erase switches on the OHP. The FCOM is also vague and says \x93continuous recording\x94, so it may be from CCS power-up.

I suspect the B787 voice recorder function operates similarly to the CVR on the B777. On the B777, the CVR operates continuously any time electrical power is applied to the aircraft. There is no dedicated switch to turn it on.

Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.

I've assumed 1Hz for the switch sampling rate and >1Hz for everything else (could be wrong) to give windows for the switch state changes.

I've also added in the ADS-B relevant data, although made no attempt to work out whether these timestamps are synchronised or not, so take them as you will.

I have assumed the cutoff is in chronological order from the report, albeit I have ignored the RAT supply timestamp in terms of chronology from the CVR recording, as that statement in the report at that time may just be due to contextual nature of the statement, rather than it happening prior to the RAT power supply. This gives a window for potentially when that statement was made (assuming also that it was made prior to reversing cutoff).

Don't think it neccessarily adds anything for me, other than:

- Would we expect ADS-B data to stop on engine transition to run? Note that ADS-B data was received between 08:08:43 and 08:08:51, so apparently only received in the time window that the switches were in "cutoff"
- The window between the switches being shut off and moved to run could be as short as 8 seconds, and the window between engine 1 and engine 2 being moved to run could be as short as 2 seconds
- The statement on the CVR could be a wide range of timepoints.

The ADS-B data is in my view odd, albeit this might be my lack of understanding. Yes, not synchronised, but unless the timestamps are way out (like 10 seconds out, and given the timestamp of max altitude, this feels incredibly unlikely), ADS-B data was transmitted without issue during phase 2 (both engines off, no RAT), and phase 3 (both engines off, RAT)...but NOT phase 4 (both engines firing back up, presumably still with RAT?). Bear in mind that phase 4 is almost half of the short flight. Also it would appear no data during phase 1 (both engines on), including during takeoff, despite receiving data during taxi?

*EDIT* - having looked into some other historical ADS-B data for this airport, albeit a bit cursory, it definitely appears that the lack of data in "phase 1" that I've outlined above is solely a coverage issue, with no other flights I can see having coverage in that area either. It's harder to determine the "phase 4" element as obviously no airplanes in a normal mode are in that geographical region at the altitude in question, but it does appear to be a reasonably safe bet that the missing datapoints are coverage related.

Thank you for the diagram. Picture = 1000 words

Really highlights how knowing precisely when the why did you cutoff" question was asked might have provided more clarity and less speculation as to how those fateful seconds played out

And it would have helped to know if Positive rate / Gear Up was called ... and when

I think in the Jeju thread, it was noted that one of the transponders was on an AC bus and the other was on the standby bus. If they had been using the other transponder (swapped each flight), then we would have had ADS-B for the full flight.

Assuming the 787 is similar, perhaps the aircraft was broadcasting ADS-B for the full flight (with the transponder running off main battery/RAT power) but the reception was marginal, resulting in no reception until just after liftoff and no reception once they start to sink again.

From the CVR, the switch position was noticed, questioned, and with understanding selected to Run; the crew apparently had a quick understanding of what would be a very surprising situation - startle, mind numbing, thought restricting conditions.

It is reported that P2 was handling; in this case the Captain might guard the thrust levers until V1, moving his hands away, but not onto the control wheel - rearwards, … thence with cuffed sleeve …

A speculative scenario of inadvertent switch operation of 'unguarded' switches.

A combination of most unlikely - unbelievable factors, which came together at that time. Yet such rarities and combinations litter the wreckage of past accidents; and with hindsight they were 'normal'.
Normal SOP for P2 takeoff; errant switches escaped SAID checks - 'normal' for that aircraft.

If the switches were inadvertently moved, the realisation, even subconsciously, might support the apparent quick understanding and action.

… waiting for: a report on the condition of the cutoff switches condition wrt guarded operation …

Back in the days before it became illegal I used to blag my way into the cockpit on short haul flights using my RAF ID card. Part of the cockpit checks, if the third seat was occupied, was the question "Pax, seat belt on and secure?" to which I always responded "Seat Belt on and secure". I am sure that that Question and Response is still used on check lists and if that is the case that Q&R would have been recorded on the CVR. That should, hopefully, do away with the 'third person in the cockpit" theory


ACW342

THE LANDING GEAR

There are many missing jigsaw pieces here that are highly relevant to building an understanding of what these guys were going through.
One being that the gear was not raised. The report ( very oddly in my opinion ) is NOT declaring any voice data on the prompts/commands to raise it once they achieved a positive ROC after lift-off.
At lift off, it's pretty safe to assume ( yes, I know ) that everything was going according to plan....so why, oh why wasn't the gear raised.....?

This is quite extraordinary because:-

1. This sequence is muscle memory for every commercial pilot. It’s drilled into simulator sessions, route checks, and emergency training. Even during non-normal scenarios like an engine failure, the gear is typically raised before handling other procedures.
   
2. The delay is not explained in the preliminary report. The gear lever was found in the DOWN position in the wreckage. No mention is made of any mechanical failure or crew discussion about the gear. That silence is notable.
   
3. There was no declared emergency prior to 180 kt. No CVR audio so far suggests anything unusual before the sudden power loss—so there was no obvious reason to skip this SOP.
   
   
   
   

With the greatest respect, I don't think any deliberate act has been proven. Allocating blame on assumptions should be avoided. People should work on facts, and then unconfirmed assumptions.

The only known fact is that engines for some reason were shut down. The other known fact is that there is a recorded indication that the start lever command was recorded as both cutoff in short succession then followed by idle detent causing a restart attempt.

I think the key unknowns here are important.
1. Was the start lever position recorded, or only the electrical signal? My money is on an electrical signal not position, therefore the manual positioning of the start levers is not conclusively proven.

2. The bulletin for locking mechanism for the start levers has been mentioned in the preliminary report. This is a huge unknown. Did that mean that in a failure that the levers could both move into cutoff at the same time? This occurred exactly as the aircraft was rotating and increasing pitch.

3. The information from the CVR if taken at face value must not be discounted. No pilot actually confirmed conclusively seeing the other move the switch. This could have been an assumption noticing an engine failure, seeing the start levers positions in cutoff or indeed seeing the start levers moved deliberately. This is a huge critical unknown.

4. One pilot asked 'why did you cutoff' and the other responded 'I didn't'. This is not a confirmation of anything for sure. In fact it is equally a suggestion no pilot moved the switches, equally as it is saying they did. This is not conclusive. This raises an important question, was this genuine, did either pilot have any reason in their life to attempt to do this and then cover their actions? There is zero suggestion here either way, but hopefully investigators will already be looking at their backgrounds and state of affairs.

5. There is no indication who or what commanded the engines back to idle detent again. There is proof of both engines attempting to restart. I would take this as confirmation of teamwork existing on the flight deck, and this would suggest a lack of deliberate interference by either pilot. Should that have been deliberately done, so much more could have happened. It just hasn't been alluded to in the preliminary report.

My own impression is that it did not appear to be a situation of a deliberate act to crash. I say this as they appear to have both tried to save the aircraft and immediately restart the engines and recover taking some critical timely actions demonstrating competent reaction.

The timing of the commanding fuel to cutoff is critical imo. The aircraft was pitching. If an accidental command to cutoff occurred then I feel this however unlikely would have been made instead of another action. The only likely thing happening at that exact time or due 2-3 seconds after lift off was gear up. The CVR and recorded timing of engine failure in relation to that challenge and response in SOP will be key imo. Did the challenge for gear up occur before the idle detent electrical signals? Also, the focus should be on that bulletin for the locking mechanism for the start levers.

I just cannot imagine an experienced crew doing this by accident and the information just doesn't suggest a deliberate act.

My post is just to highlight huge lists of unknowns. The media appears to have made their mind up that the flight crew did this. I just highlight that is definitely not confirmed yet. We have a whole list of unknowns and conflicting communication that raises more questions than they solve.

I would urge zero conclusions be made, and RIP the crew and passengers. There are zero conclusions to what happened yet in my opinion, and I think the suggestion to relatives of the flight crew and families tragically killed that this is a known pilot deliberate action simply cannot be made at this point. We must not blame the flight crew prematurely or pretend we know what happened. I think the media should take note and back off from all the assumptions.

Almost as though the hand which reached out to raise the gear while the brain was thinking about something else found the fuel cutoff switches and managed to manipulate them to off without the brain ever becoming involved?

Very helpful, thanks! One recommendation for change: since we don't know what words were used by the pilots, how about using "CVR: query cutoff" rather than "why did you cutoff"?
Most of your comments in the thread are extremely sensible but I take issue with both points you made in this post.

Firstly, you'll have seen plenty of things to disprove the "without a hitch" in this thread alone , and as a professional pilot you'll no doubt know of many others - including switches moved in-flight as a brain-fart , or switches moved by things like falling objects. Waiting for the final report may tell us if it would have made a difference in this case, but the lower tier of the safety pyramid (non-severe outcomes) is definitely already populated with plenty of examples of "hitches".

Secondly, I'm absolutely inclined to agree that the switches were moved deliberately (though perhaps absent-mindedly), but I'm genuinely shocked and baffled that you are already willing to assert that "It wasn't a brain-fart". Perhaps those words were typed in haste and you didn't re-read what you had written? (A brain-fart, in other words.)
That interview has a series of very poorly judged comments by someone who should certainly know better, and IMHO adds nothing of value. It doesn't even acknowledge the possibility of an action-slip/brain-fart/execution-error as cause, and the interviewee voices his suspicion about a cover-up based on the identities of the speakers of key remarks not being shared at this point. Surreal.

Seems fair, thanks! I rattled it off in 10 minutes so suggestions/error checking welcome

Latest version:

I don't think it's yet time to go "there".

Remember that engine 1 had actually relit and began to recover and engine 2 had also relit.
To me it's amazing that those big engines were able to do that in the time allotted.

Why would a suicidal pilot even allow the attempt to restart within 10 seconds?

Why wouldn't he yell out the other pilot's name and ask "What are you doing?" for the CVR theater performance?

This is excellent, thank you. It has helped me to crystallise a thought about the length of time the switches were at cut off.

10 seconds is a long time in a life threatening situation (like most clich\xe9s, the cinematic trope of time slowing down only reflects people's real experiences, mine included). Reaction times to completely unexpected events can be in the order of 3-5 seconds, but I find it hard to think that it would have taken any pilot as much as 5-7 seconds to set the first switch back to run. It's not something that anyone trying to save the aircraft is going to take time to consider.

Possible explanations for the length of time are a physical altercation - but if that was so, then why did the switches then stay at run? We will be none the wiser on that, at least until the next report. Another, perhaps more likely possibility is that the switch movement itself was unnoticed by at least one of the pilots, and was not noticed until its effects took hold a couple of seconds later (my phrasing here is intended to leave open the question of how the switch moved, or was moved). Combined with the startle reaction time, this would start to explain a 10 second delay. So I expect the CVR comments are towards the later end of the possible range indicated in the excellent diagram.

I'm not sure it is amazing? All I read into the report's words is that the FCSs were turned on, I assume that this will see fuel flow to the combustion chambers and ignitors within 1s, and if the fuel ignites (why not?) EGT rises and the report records this as "relit".
The low airspeed airflow through engine and HP RPM on Eng 1 were sufficient to allow HP RPM to increase. The longer delay between Eng 2 OFF then ON allowed HP RPM to decay more than #1, and although 'relit', I read a successful (unassisted) spool up was unlikely? (i.e. a detailed unassisted relight envelope including current HP RPM and IAS would have #1 in the envelope and #2 outside).

As a wild guess, if he knew it would not succeed (and it true, was correct and recovery was not even close to being possible)

To be frank, we do not know he did not. The report has been (IMHO) carefully sanitised to remove any evidence indicating it was (or not) a suicide attempt, which pilot said what, when they said it, no indication these were the exact words, and no indication that there is not plenty more conversation available.

If we want to speculate in this area, one could ask (my best guess):

1. Do the AAIB know who said "why" and who "I did not"? (Yes)
2. Are they the exact words? (No) Or a 'summary'? (Yes)
3. Were other words spoken by one of both pilots? (Yes)
4. Do the AAIB know whether there were or were not other cockpit occupants? (Yes) Were there? (No - since to fail to mention it casts assertions on just 2 named individuals)
5. Are the AAIB fairly certain of the root cause of this accident (Yes i.e. mechanical issue, unintentional HF, unlawful interference) If yes, have the AAIB deliberately sanitised this report to conceal both the root cause, and other information that would lead to uninformed speculation that does not further flight safety (Yes)

Look at the language he uses. He’s not presenting it as an option, he’s insisting it is the only option and he’s using emotive language such as murder. All whilst there are other plausible options that don’t cast aspersions on pilots whose guilt has not been proven. He is presenting it distastefully and needs moderating. It is far from professional.

There is always some virtue signalling poster on all these threads saying “we shouldn’t speculate until the full report comes out”…I’m not one of those, but I’m happy to call out someone pointing the finger when the available evidence still very inconclusive. I hope the mods frustrate him further by deleting his efforts.

When the engines are shut down, where does the power supply to the Fuel Cut Off Switches come from?
If powered by the RAT or APU would that introduce a time delay before you an can effectively put them back to Run?