July 14, 2025, 00:33:00 GMT
permalink Post: 11921803
While this is thread is still deeply into hamster wheel status, there are some valuable inputs being made. I'll try to continue with that...
Thrust lever position post-accident - it takes very little force to move the thrust levers, a little more than one pound-force at the knob. I'd be very surprised if the post impact position was the same as pre-impact (and lever angle is recorded on the FDR, so the investigators know where they were). In short - the post-accident lever position is not meaningful.
Fuel condition switch position detents - if the Indian investigators had any reason to believe that a failed or inoperative detent was a contributing fact, the authorities would have ordered a fleet-wide inspection (especially since it literally takes only seconds to do the inspection - the paperwork would take many times longer than the actual inspection).
Engine restart (i.e. "Quick Windmill Relight"): Even if the igniters were firing, at high power they won't actually spark (the electrical resistance or the air at several hundred psi prevents a spark) - so they won't spark until you get down somewhere near idle if you're close to sea level. Once the engine has dropped below the min idle, it takes a long time for it accelerate back to even an idle condition. At takeoff power, the compressor components get very hot - do a power cut the air coming in the compressor gets heated by the residual heat in the compressor. This in turn limits how fast you can add fuel in the burner without excessively back pressuring the compressor and causing a compressor stall. So it actually takes longer for the engine to accel to idle that it would during a normal (cold engine) start. The 5 seconds to 95% accel requirement referenced earlier is from a stable 'high' idle (we typically call it 'approach idle' since it's automatically selected when landing flaps are selected). Approach idle is ~10% N2 higher than the in-flight minimum idle, so that takes several more seconds. Bottom line, after initiating the Quick Windmill Relight, you're not going to have usable thrust for at least 30 seconds - probably closer to 60 seconds.
For all the complaining about this preliminary report, it actually goes into more detail than is typical.
BTW, my money is still on the 'muscle memory/action slip' or whatever you want to call it. I can easily imagine a scenario along the line of 'why did you turn off the fuel' - 'I didn't - oh wait - oh
...
Thrust lever position post-accident - it takes very little force to move the thrust levers, a little more than one pound-force at the knob. I'd be very surprised if the post impact position was the same as pre-impact (and lever angle is recorded on the FDR, so the investigators know where they were). In short - the post-accident lever position is not meaningful.
Fuel condition switch position detents - if the Indian investigators had any reason to believe that a failed or inoperative detent was a contributing fact, the authorities would have ordered a fleet-wide inspection (especially since it literally takes only seconds to do the inspection - the paperwork would take many times longer than the actual inspection).
Engine restart (i.e. "Quick Windmill Relight"): Even if the igniters were firing, at high power they won't actually spark (the electrical resistance or the air at several hundred psi prevents a spark) - so they won't spark until you get down somewhere near idle if you're close to sea level. Once the engine has dropped below the min idle, it takes a long time for it accelerate back to even an idle condition. At takeoff power, the compressor components get very hot - do a power cut the air coming in the compressor gets heated by the residual heat in the compressor. This in turn limits how fast you can add fuel in the burner without excessively back pressuring the compressor and causing a compressor stall. So it actually takes longer for the engine to accel to idle that it would during a normal (cold engine) start. The 5 seconds to 95% accel requirement referenced earlier is from a stable 'high' idle (we typically call it 'approach idle' since it's automatically selected when landing flaps are selected). Approach idle is ~10% N2 higher than the in-flight minimum idle, so that takes several more seconds. Bottom line, after initiating the Quick Windmill Relight, you're not going to have usable thrust for at least 30 seconds - probably closer to 60 seconds.
For all the complaining about this preliminary report, it actually goes into more detail than is typical.
BTW, my money is still on the 'muscle memory/action slip' or whatever you want to call it. I can easily imagine a scenario along the line of 'why did you turn off the fuel' - 'I didn't - oh wait - oh
...
The last line, is not a zero possibility, but at present the whole wiring system for the fuel control switches would need to be evaluated for any potential common fault that may be intermittent before I would lean towards the cognitive slip type error. The poor old FO would have both hands on the yoke from V1, irrespective of the company's SOP and so would have been rather unpleasantly surprised by the loss of performance. I think the 10 seconds in this case is remarkably fast observation-orientation-decision-action sequence, and that one engine had already started to recover towards operation is a credit to the design of the engine.
July 14, 2025, 00:43:00 GMT
permalink Post: 11921808
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.
in an era where pilot malfeasance is the single largest cause of deaths in RPT operations, this is inevitable
Two reasons
1. Will have some deterrent value. With MH370 and here, we see some effort to create confusion and ambiguity rather than perform a simple act
2. Will aid investigation of further incidents (which are also inevitable)
July 14, 2025, 02:38:00 GMT
permalink Post: 11921831
I think we'll need to agree to disagree, since those cameras won't prevent any accident (all they'll do is improve post mortems) but they will create a hostile work environment which is not healthy for corporate or flight deck culture.
Your ref to MH370 is noted, and also not agreed either.
Suggest you read up on how to stop terror attacks. The psychology of what is operating there is quite similar. The perp has the initiative.
As to AF 447, the data from a sub-system provided some useful info
(before the aircraft was found and then the FDR and CVR changed the story considerably)
that was not intrusive.
July 14, 2025, 03:46:00 GMT
permalink Post: 11921841
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.
Originally Posted by
Lonewolf 50
Disagree. It creates a hostile work environment. You don't need that in the cockpit / on the flight deck.
Just need to ask: are you involved in airline management?
Just need to ask: are you involved in airline management?
Granted, accident investigates are good at what they do, and I'm in awe of their ability to reconstruct the majority of accidents to determine the ultimate cause (without video). but when technology is available that would have already solved this accident ie. "On-board CCTV shows the Effo selecting the engine run switches to OFF for reasons that remain under investigation" (and to be clear, I AM NOT suggesting that's actually what happened...), it would solve a lot of issues and put to bed speculation about what actually happened to the fuel control switches, who did what and when and I'm at a genuine loss as to why people would argue against it, when it's already so widespread and entrenched in other industries.
Even now - with the preliminary report, I haven't seen mention of which pilot asked the other "Why did you [go to] CUTOFF?" whereas a video would have already told the whole story of this accident - with the exception of the why?
July 14, 2025, 04:21:00 GMT
permalink Post: 11921849
My final thoughts for this event.
Misinformation, most of us including myself was of the view that Gear Up had been selected because we saw an image believed to be the accident aircraft with the bogeys stowed for retraction.The report image shows that they were not and the Gear Selector was down. A crucial element in the sequence of events.
The preliminary report around the cause is deliberately vague for obvious reasons.The investigators would know exactly what was done/said and by who. The clack clack of the fuel switches would be on the CVR and align with the FDR. The First Officer was the Pilot Flying and his control inputs would be on the FDR (trim operation) when the engines were commanded to shutdown.
The full version will leak otherwise we have to wait for the Final Report. I'm of the view that the only thing misunderstood was the Captains meaning of Retirement..
Misinformation, most of us including myself was of the view that Gear Up had been selected because we saw an image believed to be the accident aircraft with the bogeys stowed for retraction.The report image shows that they were not and the Gear Selector was down. A crucial element in the sequence of events.
The preliminary report around the cause is deliberately vague for obvious reasons.The investigators would know exactly what was done/said and by who. The clack clack of the fuel switches would be on the CVR and align with the FDR. The First Officer was the Pilot Flying and his control inputs would be on the FDR (trim operation) when the engines were commanded to shutdown.
The full version will leak otherwise we have to wait for the Final Report. I'm of the view that the only thing misunderstood was the Captains meaning of Retirement..
July 14, 2025, 04:55:00 GMT
permalink Post: 11921857
Just to clarify, I'm not aware of any confirmation at this point that the Fuel Cutoff switches were
physically
moved from RUN to CUTOFF and back again.
We do have evidence that the FDR, thus the databus, received signals that the Fuel Cutoff switches were in the RUN position, then the signals changed to CUTOFF one second apart, and then back to RUN at four second intervals.
In the absence of video, we could only use CVR data to determine that the switches were physically moved - either through flight crew conversation or sound of switches being moved.
When the PF asks why the PNF "Why did you cut off" we don't know whether he concluded the fuel was cutoff by checking the physical position of the switches or through instrument annunciations.
I accept that with sampling rates the physical movement of switches to CUTOFF at one second intervals could be logically explained. I can understand why there would be such an interval between physically moving the two switches back to RUN, unless there was some sort of struggle which presumably would be easily detectable on CVR.
Unless I've missed something, I'm not ready to conclude that the switches ever physically moved.
We do have evidence that the FDR, thus the databus, received signals that the Fuel Cutoff switches were in the RUN position, then the signals changed to CUTOFF one second apart, and then back to RUN at four second intervals.
In the absence of video, we could only use CVR data to determine that the switches were physically moved - either through flight crew conversation or sound of switches being moved.
When the PF asks why the PNF "Why did you cut off" we don't know whether he concluded the fuel was cutoff by checking the physical position of the switches or through instrument annunciations.
I accept that with sampling rates the physical movement of switches to CUTOFF at one second intervals could be logically explained. I can understand why there would be such an interval between physically moving the two switches back to RUN, unless there was some sort of struggle which presumably would be easily detectable on CVR.
Unless I've missed something, I'm not ready to conclude that the switches ever physically moved.
July 14, 2025, 06:02:00 GMT
permalink Post: 11921875
Looking at some past FDR data, it appears that the fuel cutoff switches are sampled at 1 Hz, but the actual valve position is sampled at 4 Hz. The position of the fire switch (fire handle) is also recorded. N1 and N2 are sampled at 1 Hz.
July 14, 2025, 06:10:00 GMT
permalink Post: 11921882
That's interesting and potentially tightens the time window a little (if one presumes that the valve position is a proxy of switch position, which in this case there's no reason to believe otherwise, and if the prelim uses this info to feed it's timestamps which I'd loosely assume it probably does...).
July 14, 2025, 08:17:00 GMT
permalink Post: 11921942
what is the big deal about flight deck cameras? if it is treated the same way as the FDR then what is the problem?
July 14, 2025, 08:20:00 GMT
permalink Post: 11921944
July 14, 2025, 08:22:00 GMT
permalink Post: 11921946
Korea has made CCTV mandatory in operating theatres
.
I work in a facility where cameras outnumber staff on site roughly 3:1.
Various forms of public transport (trains, buses, trams, I assume many boats) have ubiquitous external, internal, and in at least some cases driver facing CCTV.
Plant control rooms (including power stations, dams, and chemical facilities) have ubiquitous CCTV.
Driver-facing cameras with alerting and KPIs for events like speeding, hard braking, phone usage/distracted driving, and fatigue detection are becoming increasingly common for fleet vehicles, thanks largely to hefty insurer discounts. That's not just heavy trucks but things like HVAC installers, linemen, and ambulances.
I suspect anyone who thinks this will never happen in aviation is being rather optimistic.
CVR is likely what was meant.
I work in a facility where cameras outnumber staff on site roughly 3:1.
Various forms of public transport (trains, buses, trams, I assume many boats) have ubiquitous external, internal, and in at least some cases driver facing CCTV.
Plant control rooms (including power stations, dams, and chemical facilities) have ubiquitous CCTV.
Driver-facing cameras with alerting and KPIs for events like speeding, hard braking, phone usage/distracted driving, and fatigue detection are becoming increasingly common for fleet vehicles, thanks largely to hefty insurer discounts. That's not just heavy trucks but things like HVAC installers, linemen, and ambulances.
I suspect anyone who thinks this will never happen in aviation is being rather optimistic.
CVR is likely what was meant.
July 14, 2025, 08:50:00 GMT
permalink Post: 11921971
Recording images/videos is prevented by similar union/regulator agreements AFAIK . It might take this accident to change that, of note the GE EAFR fitted to the 787 has the capability:
The EAFR is capable of providing combinations of any or all of the mandatory crash protected recorder functions in a single Line Replaceable Unit (LRU). The EAFR functions include the Digital Flight Data Recorder (DFDR) function, the Cockpit Voice Recorder (CVR) function, the Data Link recording function,
and Image Recording function growth
Includes growth for Image recording (5 Gigabytes Crash Protected Memory) .
The Image Recorder growth function is used to record visual images of the flight deck instruments, flight deck, the aircraft structures, and engines as required. The Image Recorder function is capable of receiving a digital 10/100 Mbit Ethernet data stream of cockpit images and stores this data in the Crash Protected Memory in a separate partition. Even though the image recording duration will be governed by regulations , the EAFR Crash Protected Memory capacity has the storage capacity for two hours of image data recording per EUROCAE ED-112 requirements. Data in the Image Recording Crash Protected Memory partition can only be downloaded when the EAFR is off the aircraft.
Includes growth for Image recording (5 Gigabytes Crash Protected Memory) .
The Image Recorder growth function is used to record visual images of the flight deck instruments, flight deck, the aircraft structures, and engines as required. The Image Recorder function is capable of receiving a digital 10/100 Mbit Ethernet data stream of cockpit images and stores this data in the Crash Protected Memory in a separate partition. Even though the image recording duration will be governed by regulations , the EAFR Crash Protected Memory capacity has the storage capacity for two hours of image data recording per EUROCAE ED-112 requirements. Data in the Image Recording Crash Protected Memory partition can only be downloaded when the EAFR is off the aircraft.
July 14, 2025, 10:34:00 GMT
permalink Post: 11922058
"Quickly solving" (which in your post means finding soneone to blame) an accident does not mean improving safety. A CCTV is NOT a preventive measure, and CVR and FDR proved to provide enough data to conduct a proper safety investigation.
A camera right in your face 24/7 does nothing to improve safety, and could also lead to inactions for fear of repercussion. Anyway, if you want camera be my guest, with the only condition to introduce AI fatigue recognition. That's be a blast, as written above.
Oh, by the way...saying "a lot of people are already being recorded at work" means less than nothing.
Last edited by bulldog89; 14th July 2025 at 11:18 .
July 14, 2025, 12:07:00 GMT
permalink Post: 11922137
We wouldn't have the video for MH370 even if a camera was installed, so, no, it wouldn't.
Does it make sense to have the data stored only on the plane, and then flown to the scene of the crash? Once crashed, the data may never be found (MH370 thus far), may take years to find (AF447), or may be found to be damaged / compromised.
July 14, 2025, 12:16:00 GMT
permalink Post: 11922149
I suspect the other push will be for some streaming to a ground station. CVR / FDR have served us well. But the world and technology have both moved on a lot these last 70 years.
Does it make sense to have the data stored only on the plane, and then flown to the scene of the crash? Once crashed, the data may never be found (MH370 thus far), may take years to find (AF447), or may be found to be damaged / compromised.
Does it make sense to have the data stored only on the plane, and then flown to the scene of the crash? Once crashed, the data may never be found (MH370 thus far), may take years to find (AF447), or may be found to be damaged / compromised.
July 14, 2025, 21:09:00 GMT
permalink Post: 11922503
Again, not familiar with the specifics of the 787, but on the 747-400/-8, one pole of the fuel switch feeds EICAS - which uses it in various message logic - and sends it out to any other aircraft systems that use it. There is "Digital Flight Data Acquisition Unit) DFDAU .... that takes all the various system digital signals, sorts them and provides them to the DFDR and QAR. The 787 has something similar to the DFDAU but I don't recall what it's called.
The other 2 contact sets feed latching relays (again driven each coil independently by dropping to GND at the switch) that then drive spar valves and reset signals to the FADEC Channels. (and more).
So - for the benefit of those that hang on to the 'possibility' of electrical gremlins and 'ghost' switch signals.
Each switch has 4 mechanically separated 'channels' - 2 of which do electromechanical things to the engines through separate paths, the other 2 feed through independent paths the FDR and the rest of the computer systems. The results of the electromechanical actions also feed back to the FDR.
Thus the readout from the EAFR will PROVE that the switches MUST have been PHYSICALLY MOVED.
And - I'm nervous to challenge you tdracer - there's quite the authority gradient and I know I'm at the bottom end, but I can't let this fly...
Its 'Deefer Doo'. Fight me.
July 15, 2025, 01:45:00 GMT
permalink Post: 11922617
There is no way any pilot would be touching the stab trim switches right after rotation. It would go against every aspect of training. If the aircraft is flying ok you would never touch anything trim related until after cleanup and working the appropriate QRH or EICAS. I know some will bring up the Delta flight at LAX however that occurred above a 1000 feet and was in compliance with company policy and Boeing at the time where you got one free punch to reset the EEC.
It would also have been a data point on the FDR and in the preliminary report.
It would also have been a data point on the FDR and in the preliminary report.
July 15, 2025, 09:46:00 GMT
permalink Post: 11922785
From post #918 (number as at the time of this post):
I've desperately grasped at technical rather than human factors as the explanation for this tragedy, but have had to abandon that hope.
So - for the benefit of those that hang on to the 'possibility' of electrical gremlins and 'ghost' switch signals.
Each switch has 4 mechanically separated 'channels' - 2 of which do electromechanical things to the engines through separate paths, the other 2 feed through independent paths the FDR and the rest of the computer systems. The results of the electromechanical actions also feed back to the FDR.
Thus the readout from the EAFR will PROVE that the switches MUST have been PHYSICALLY MOVED.
Each switch has 4 mechanically separated 'channels' - 2 of which do electromechanical things to the engines through separate paths, the other 2 feed through independent paths the FDR and the rest of the computer systems. The results of the electromechanical actions also feed back to the FDR.
Thus the readout from the EAFR will PROVE that the switches MUST have been PHYSICALLY MOVED.
I've desperately grasped at technical rather than human factors as the explanation for this tragedy, but have had to abandon that hope.
July 15, 2025, 11:36:00 GMT
permalink Post: 11922860
July 15, 2025, 15:58:00 GMT
permalink Post: 11923045
The facts of the case are: that the FDR recorded that the switches were moved from RUN to CUTOFF, that the engines shut down, that one pilot accused another of having set the switches to CUTOFF, and that subsequently they were set back to RUN and that at least one engine had started to recover before impact.
Think what it would take for you to verbally accuse your colleague of having shut the engines down seconds after liftoff. I hope you agree that looking and seeing that the switches are set to CUTOFF is a bare minimum for you to say something like that.
Any theory where there is some sort of short-circuit or anything like that is a non-starter for this reason. It does not accord with what is on the CVR. The one and only thing that jibes with both the FDR and CVR is that the switches were physically moved from RUN to CUTOFF. The only remaining argument is whether this was done deliberately or as part of some monumental brain fart. I just don't see how it is possible to argue anything else. Even in some incredibly unlikely event where two switches malfunction at once, it is near impossible that one pilot would accuse another of cutting off fuel to the engines without visual evidence to back him up. Either the switches were in fact switched to CUTOFF or you are left explaining not one but two independent and virtually impossible events.
Think what it would take for you to verbally accuse your colleague of having shut the engines down seconds after liftoff. I hope you agree that looking and seeing that the switches are set to CUTOFF is a bare minimum for you to say something like that.
Any theory where there is some sort of short-circuit or anything like that is a non-starter for this reason. It does not accord with what is on the CVR. The one and only thing that jibes with both the FDR and CVR is that the switches were physically moved from RUN to CUTOFF. The only remaining argument is whether this was done deliberately or as part of some monumental brain fart. I just don't see how it is possible to argue anything else. Even in some incredibly unlikely event where two switches malfunction at once, it is near impossible that one pilot would accuse another of cutting off fuel to the engines without visual evidence to back him up. Either the switches were in fact switched to CUTOFF or you are left explaining not one but two independent and virtually impossible events.