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CharlieMike
July 13, 2025, 09:15:00 GMT permalink Post: 11921169 |
I don't see any evidence here. The report doesn't mention any callout of positive rate or request for gear up. The cutoff switches were moved ~3 seconds after wheels leaving the ground which would have been just before or at roughly the same time as the callout. The report did not say "pilot flying requested gear up and then the switches were moved to cutoff". There is also no evidence of a 3rd person and I'm not even sure how that would make a difference.
I see 3 meaningful explanations roughly by order of probability
(1) It\x92s still a likely response to ask that question if your colleague had just switched them off by action-slip. (2) See my post above. Routine use of these switches is in one \x93event\x94\x85below OAT 40C you start both simultaneously and at shutdown you operate one straight after another. (3) The interim report seems to leave out all information on verbal exchanges not specifically involved with a response to the abnormal situation. Not saying you aren\x92t correct, but it doesn\x92t change the order of likelihood in my mind. 1 user liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Mrshed
July 13, 2025, 10:13:00 GMT permalink Post: 11921202 |
![]() 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. Last edited by Mrshed; 13th July 2025 at 11:47 . 15 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
unworry
July 13, 2025, 10:23:00 GMT permalink Post: 11921207 |
![]() 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). 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 Last edited by unworry; 13th July 2025 at 12:19 . 2 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Someone Somewhere
July 13, 2025, 10:32:00 GMT permalink Post: 11921213 |
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? 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. 1 user liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Sailvi767
July 13, 2025, 10:36:00 GMT permalink Post: 11921215 |
Does the EAFR record the electrical / physical contact of the RUN / CUTOFF switch or, does it record a software 'EVENT' which has the same 'signature' as the RUN / CUTOFF switch being toggled. My thoughts are that the RUN / CUTOFF switch never moved but, the underlying software / hardware system mal-functioned triggering a scenario similar to both RUN / CUTOFF switches being triggered
Some Boeing SB's describe circuit board failures triggering all sorts of unexpected / unpredictable failures 2 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
safetypee
July 13, 2025, 11:12:00 GMT permalink Post: 11921236 |
'Normal' Accidents
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 … Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
adfad
July 13, 2025, 11:13:00 GMT permalink Post: 11921238 |
I\x92d counter that order of likelihood by suggesting
(1) It\x92s still a likely response to ask that question if your colleague had just switched them off by action-slip. (2) See my post above. Routine use of these switches is in one \x93event\x94\x85below OAT 40C you start both simultaneously and at shutdown you operate one straight after another. (3) The interim report seems to leave out all information on verbal exchanges not specifically involved with a response to the abnormal situation. Not saying you aren\x92t correct, but it doesn\x92t change the order of likelihood in my mind. By precedent in routine operations I mean: is there a single example of these switches being cut off at takeoff like this? There is precedent for the wrong engine being shut down in a fire sure, and there is perhaps precedent for mishaps with the fuel switches in other cockpit layouts - but in the case of this layout, with this model of switch or even this 'style' of switch and placement, I cannot find a single example that would come close to the level of catastrophic action slip of pulling out and setting to cutoff both switches one by one. I think the preliminary report is supposed to present all factual information - they could have left out "why did you cutoff / I did not" - I could understand if they left out sounds that could be ambiguous, perhaps indicating a struggle but not clear enough to present as fact. However, "positive rate / gear up" followed by 2 switches instead of gear handle is completely factual and relevant information, to exclude it makes no sense. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Captain Biggles 101
July 13, 2025, 11:24:00 GMT permalink Post: 11921244 |
It actually doesn\x92t matter who said it for the purposes of diagnosing deliberate action, if it\x92s someone trying to cover their tracks and deflect blame onto the other person it still represents cognition that the movement of the switches was a deliberate act and will have been recorded as such.
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. Last edited by Captain Biggles 101; 14th July 2025 at 09:29 . 3 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
paulross
July 13, 2025, 11:27:00 GMT permalink Post: 11921247 |
AI171 Thread by Subject
I have rebuilt the site that organises this thread by subject here:
https://paulross.github.io/pprune-th...171/index.html
It studies 3703 posts (and discards 1043 of them). Changes: - Add subjects: "Action slip", "AvHerald", "Human Factors", 'Pilot "Why did you cut off"'. - Build threads up to July 13, 2025, 10:57:00 (built on July 13, 2025, 12:02:17). Project is here: https://github.com/paulross/pprune-threads Raise issues here https://github.com/paulross/pprune-threads/issues or PM me. 4 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
CharlieMike
July 13, 2025, 11:28:00 GMT permalink Post: 11921248 |
(1) is true I give you that, but there is no followup "I didn't.. oh crap", denial is a reasonable response if you truly haven't registered doing something, but it is also a reasonable response if you want to confuse to delay
By precedent in routine operations I mean: is there a single example of these switches being cut off at takeoff like this? There is precedent for the wrong engine being shut down in a fire sure, and there is perhaps precedent for mishaps with the fuel switches in other cockpit layouts - but in the case of this layout, with this model of switch or even this 'style' of switch and placement, I cannot find a single example that would come close to the level of catastrophic action slip of pulling out and setting to cutoff both switches one by one. I think the preliminary report is supposed to present all factual information - they could have left out "why did you cutoff / I did not" - I could understand if they left out sounds that could be ambiguous, perhaps indicating a struggle but not clear enough to present as fact. However, "positive rate / gear up" followed by 2 switches instead of gear handle is completely factual and relevant information, to exclude it makes no sense. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Natterjak
July 13, 2025, 11:29:00 GMT permalink Post: 11921250 |
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:-
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njc
July 13, 2025, 11:43:00 GMT permalink Post: 11921256 |
@Maybeitis,
how about we leave the total redesign of the fuel switch locations and operation (which have been moved billions of times in thousands of aircraft without a hitch) until the final report is out.
These were deliberately moved. It wasn't a brain-fart. Unless the interim report omits crew calls which turn the scenario on it's head. 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.)
You don\x92t \x93flick switches in the Sim\x94 for no apparent reason.
Even Indian sources are now reporting on the possibility of intent. https://www.ndtv.com/india-news/air-...-probe-8864239 4 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
GroundedSpanner
July 13, 2025, 11:49:00 GMT permalink Post: 11921258 |
Some facts
From the Manuals AMM - IPD - WDM - CMM - Avoiding speculation in this post. Just Facts.
Cutoff Switch Each switch has 14 pins - 4 sets of contacts Designation | Cutoff | Common | Run A | 1 | 2 | 3 B | 4 | 5 | 6 C | 7 | 8 | 9 D | 10 | 11 | 12 Pins 13 and 14 power the LED - Powered by Capt Instrument bus 28vdc - signal from common core sys A Contacts feed an RDC B Contacts feed a different RDC C Leads to Engine Fuel Control Relay 2(L or R) D Leads to Engine Fuel Control Relay 1(L or R) AND Engine Fuel Relay 1 The common pins are all GND. Positive voltage is suppled to the cutoff and run pins. The relays - do various things. I cant detail everywhere they lead to. The AMM States that the manufacturer for the engine fuel control switches has determined that you should not replace the switches on-wing, and that you should replace the thrust control module instead. Thrust Control Module This LRU (replaced twice per the interim report) - contains the cutoff switches. The CMM for the Thrust Control Module does not call out a test of the locking feature that I can find. It does perform various tests of the switch function. 15 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Mrshed
July 13, 2025, 11:50:00 GMT permalink Post: 11921259 |
![]() Latest version: ![]() 7 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Buster15
July 13, 2025, 12:13:00 GMT permalink Post: 11921274 |
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pjumbo
July 13, 2025, 12:19:00 GMT permalink Post: 11921279 |
I assure you, if both donkeys start rolling back and the other guy asks why I closed the masters when I hadn't, that fact is extremely likely to verbalised.
I would look at this from the other way and suggest it doesn't sit right as if someone had just done it deliberately, seconds after rotation, why would they bother denying it, if you see what I mean? To place the 'blame' on the other pilot, knowing that the audio would be listened to at the subsequent investigation. I.e. possible scenario... Pilot A selects the switches to 'cut off'. Pilot A asks why 'he' (pilot B) did that. Pilot B (indignantly and truthfully) says 'I did not do that'. Hence 'listeners' assume that Pilot B selected the switches to 'Cut off' because why would Pilot A ask the question if he did it himself. That's a worse case scenario of the aircraft being brought down deliberately and one of the pilots trying to place the blame on the other one. But we cannot know more until the final report is published. And until medical reports are conducted on the pilots. We can only hope that this scenario is not true and that there is some other reason for this tragic incident. 3 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Seamless
July 13, 2025, 12:23:00 GMT permalink Post: 11921283 |
(SLF / Lawyer) I wrote early in the old thread that realistically only the FCS could be considered, pointing to the bulletin and suggesting that a foreign object might have affected both FCS simultaneously. After everything I've read here, I stick to that. Why? If the F/O was the PF, then only the PM could have operated the FCS. An unconscious action seems unlikely because it would have required not one but two unconscious actions, even if in quick succession. I consider that rather improbable. If it was a conscious action, wouldn\x92t the captain have taken over the flight instead? Unless one argues that the FCS had the lowest threshold and promised the safest outcome in this situation. Pilots could probably assess that better. But: How would it have turned out if the PF had reacted immediately and switched the FCS back on? Would the aircraft have been salvageable? If so, wouldn\x92t the PM have wanted to prevent this scenario and re-deactivated the FCS in Cut off position? In short: I think there are safer methods. Or am I mistaken?
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Easy Street
July 13, 2025, 12:43:00 GMT permalink Post: 11921296 |
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. 2 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
Gupeg
July 13, 2025, 12:59:00 GMT permalink Post: 11921303 |
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). If we want to speculate in this area, one could ask (my best guess):
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adfad
July 13, 2025, 13:01:00 GMT permalink Post: 11921309 |
The fact is the moment the report was released all other previous theories were all but invalidated and deliberate action became 2nd or 1st most probable.
I do agree that at this point deliberate action is the most likely cause, followed by extreme psychological episode. Casual accidental movement if it was remotely probable would surely have been detected in decades of operation and mitigated with a redesign. 3 users liked this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
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