^^^makes the more sense^^^ than any other explanation I've heard.

https://www.ndtv.com/india-new...nistry-8841505/amp/1


They seem rather interested in the position of the fuel cutoff switches in the cockpit. I think they were too low for any ‘mistaken’ cutoff of the good engine scenario.

If the fuel control switches were in cutoff position, that would explain most everything.

Lots of good discussion here, including much I can’t begin to understand ( ), but now it’s my turn to express skepticism that mistakes/improper actions by pilot(s) would necessarily be announced immediately. One possible reason to slow walk any reports would be, “What‽ What kind of people do you hire, and what sort of training do they receive?” I suspect that certain airline companies in certain parts of the world don’t have the best reputations as it is, and another “Here we go again” might just make people even less likely to fly with them. Plus if there were any indication of a deliberate act, I can think of several reasons why some companies and countries would like to keep that out of public knowledge.

Looks like the fuel cutoff switches were moved by the pilot

The article states "It is not known to TAC whether one or both of the fuel control switches for the GE engines in the cockpit were moved in the moments after takeoff from Runway 23 Ahmedabad." That's just a generic photo of the switches.



However, the article also has an interesting tidbit: "The 787's advanced fly-by-wire flight control system automatically compensates for any difference in thrust coming from one of the engines. Unlike the earlier-generation 777, the 787's flaperons, ailerons and rudder would automatically and fully adjust to keep the aircraft flying straight and not yawing toward from the ailing engine. The pilots also receive a tactile cue to asymmetric thrust with the automatic movement of the rudder pedals."

This would lend support to the theory that a single engine failure and subsequent shutdown of the wrong engine could have occurred without a noticeable visible shift in the plane's flight behavior.

Also interesting is that the Indian authorities said a few days ago that they cannot rule out sabotage. The article also stated that TAC was told that it's not a design or mechanical issue with the plane nor its engines.

quote:

Originally posted by kkina:

This would lend support to the theory that a single engine failure and subsequent shutdown of the wrong engine could have occurred without a noticeable visible shift in the plane's flight behavior.

The system does not work instantaneously. There would still be a noticeable yaw or observable movement of the aircraft before the system corrected the imbalance.

The deliberate manipulation of the fuel control switches does appear to be the leading theory though. And maybe not even a theory. The Air Current is pretty reputable and usually has very good sources, so they would seem to know something. The question then is why those switches were moved.

Some mention of releasing a preliminary report tomorrow, the 11th.

Looking at some numbers, reportedly the highest altitude reached was 436’ AGL, crash was 33 seconds after liftoff. With a ‘normal’ takeoff, we have to assume both engines were producing takeoff thrust at least to V1 speed, rather fast.

What I’m getting at is, this ‘failure window’ was fairly narrow. Things were assumed to be fine at V1, then fell apart just seconds later.

During the takeoff roll the engines are spooled up, presumably working just fine on the takeoff roll. I don’t see some of the earlier speculation as likely, fuel issues, FADEC electrical malfunction, etc..

I think they are spending these days getting the wording ‘right’, minimizing the fallout.

Pilot Error.

https://www.standard.co.uk/new...atwick-b1237753.html

Investigators probing the Air India crash that killed at least 260 people believe the actions of the jet’s pilots may have led to the crash, according to reports.

Preliminary findings of the investigation into the Ahmedabad crash last month indicate that switches controlling fuel flow to the jet’s two engines were turned off, according to sources familiar with the US side of the investigation.

This led to an apparent loss of thrust for the Boeing 787 Dreamliner shortly after takeoff, the Wall Street Journal reported.
The switches would normally be on during flight, and it is unclear how or why they were turned off, said the newspaper's sources familiar with US officials’ early assessments.

If the switches were off, that could explain why the jet’s emergency-power generator—known as a ram air turbine, or RAT—appears to have activated in the moments before the aircraft plummeted, its report stated.

It is almost impossible to turn the stitches off accidentally, but sources say the black box analysis has so far been unable to rule out “improper, inadvertent or intentional” action that caused them to be moved from the ‘RUN’ position to ‘CUTOFF’, the Sun reported.

I'd like to know exactly what "preliminary findings" means. Was it actually recorded on the FDR that the switches were thrown? Did they actually find the switches? How did they rule out automatic activation of the fuel shutoff valves?

The report had more of a tone that they are unable at this time to rule out pilot action as a causative factor in the crash. That really says nothing. This seems more like a hyped up rumor of a rumor.

This story was probably the result of a leak of the report due today. I have not found the full report yet, which should answer some of these questions with respect to what the flight data recorder says.

OK, more details have emerged with the preliminary report, and there does seem to be stronger and darker implications regarding pilot action in this incident.

The fuel cutoffs occurred 1 second apart, consistent with manual operation of the switches. Simultaneous activation would be more consistent with auto-shutoff.

Then a very irregular, let's say shocking, excerpt from the voice recorder: one of the pilots can be heard asking the other "why did he cutoff," while "the other pilot responded that he did not do so."

Hard to believe this was just an error considering how the safetied switches are designed. Murder-suicide?

(Unfortunately the switches were apparently returned to the RUN position shortly after, so a pic of the cockpit switches in their final position would not be useful.)

CNN

Copy of the report:

[https://aaib.gov.in/What's%20New%20Assets/Preliminary%20Report%20VT-ANB.pdf]

The just went off? I’m having Deja vu.

There is an AD on the fuel switches.

The FAA SAIB (Special Airworthiness Information Bulletin, a lower level than an AD - Airwortiness Directive) appears to be especially concerned with the Honeywell manufactured fuel cutoff switches specifically for the 737:

“1) Inspect the locking feature of the fuel control switch to ensure its engagement. While the airplane is on the ground, check whether the fuel control switch can be moved between the two positions without lifting up the switch. If the switch can be moved without lifting it up, the locking feature has been disengaged and the switch should be replaced at the earliest opportunity.

2) For Boeing Model 737-7C0, -700C, -800, and -900ER series airplanes and Boeing Model 737-8 and -9 airplanes delivered with a fuel control switch having P/N 766AT613-3D: Replace the fuel control switch with a switch having P/N 766AT614-3D, which includes an improved locking feature.“

No. 1 above is a recommendation to check the fuel cutoff switches on a variety of Boeing and MD aircraft for proper lockout function while No. 2 is a recommendation to replace the switches specific to the 737. FAA NM-18-33

I have never personally experienced nor heard of a gated switch like those failing the locking function. The metal would have to be worn very substantially.

I do know of one incident where a cockpit manual fell from the glare-shield onto such a switch on the pedestal and accidentally changed its position. I don't see how any such accidental mivement could happen on the 787 given the location of the switches behind the thrust levers, and the reported 1 second between each switch going to OFF.

If the switches were found in the ON position in the wreckage, either a human moved them to OFF and then later a human moved them to ON, or the switches never moved position and something elsewhere triggered the circuitry which the FDR reportedly recorded as an OFF position.

As I hear about the switch issue. I am curious what exact info the flight recorder records. Does it merely log that the switch circuit changed states or does it log that the switch was physically operated and if whether the flight control computer activating the fuel shut off would be recorded “differently” as a software controlled change vs a hardware controlled input.

When the “system” automatically shuts the fuel flow off, is the physical switch mechanically actuated somehow or is the switch circuit bypassed?

Lots of folks on the various groups discussing this are commenting ”don’t jump to conclusions and disparage the pilots” it seems to me if the system recorded a physical manipulation of the switches, and the switch can only be flipped by a person, that along with the audio exchange between the pilots it seems more likely than not that this may have been a murder/suicide. It has happened before and evidently Air India is a sub-par airline so potentially could be less oversight on psych issues of it crews, stress levels, etc. Seems they are pretty slack on maint issues so not a stretch to fall short on personnel issues as well.

I would think that the data recorder records the actual position of the manual switch, and separately monitors any other automatic switches in the system. But it is an electronic system with lots of computers and software so I really don't know. My opinion is that recording manual control inputs is a critical function so investigators can know exactly what the pilots did.

Either of these happened:


1) The fuel cutoff happened on its own, the manual switches weren't touched, and the responding pilot was honestly saying he didn't cut off. This would require that the data recorder cannot determine the actual manual switch position and is relying on other parts of the system.

2) A pilot manually actuated the cutoff switches but intended to do something else and had a massive brain fart. He did not realize he had cut off the fuel, and was honestly responding that he believed he didn't. What other thing he possibly meant to do would be best answered by pilots - Raise gear? Adjust flaps?

3) Pilot intentionally cut off the fuel for unknown reasons and lied about it to the other pilot.

quote:

Originally posted by 911Boss:
As I hear about the switch issue. I am curious what exact info the flight recorder records. Does it merely log that the switch circuit changed states or does it log that the switch was physically operated and if whether the flight control computer activating the fuel shut off would be recorded “differently” as a software controlled change vs a hardware controlled input.

When the “system” automatically shuts the fuel flow off, is the physical switch mechanically actuated somehow or is the switch circuit bypassed?

Lots of folks on the various groups discussing this are commenting ”don’t jump to conclusions and disparage the pilots” it seems to me if the system recorded a physical manipulation of the switches, and the switch can only be flipped by a person, that along with the audio exchange between the pilots it seems more likely than not that this may have been a murder/suicide. It has happened before and evidently Air India is a sub-par airline so potentially could be less oversight on psych issues of it crews, stress levels, etc. Seems they are pretty slack on maint issues so not a stretch to fall short on personnel issues as well.

1) I've never seen a switch like those that has any kind of servo that moves it. It is a toggle switch with a mechanical rectangular bump between the On and Off positions. The switch tip is spring loaded down, and has to be pulled up to get over the bump, and then moved to the other position. Lift, move, release. Every airliner and bizjet I flew for 30 years had a multitude of those switches, and they were all the same design, and I have never experienced one anywhere near able to be accidentally moved without lifting it over the bump or gate.

2) Idk what exactly the FDR records. If the switch has multiple poles, one set could go to the engine control electronics and the other to the FDR. But my guess (that is all it is) is that the FDR records from the data bus for the state of all the switches. A digital system somewhere detects the state of the switch and then uses that information to command further downstream actions such as FADEC. Everything is data over buses in modern airliners. Even circuit breakers in the cockpit are remote control for physical breakers elsewhere.

3) The fact that there was about a second difference it time recorded between the two switches showing OFF, it suggests human physical action. That is well within the normal time used when shutting down the engines at the gate. However, I would not yet rule out some cascading system failure. Many backup or detection systems on modern aircraft have short delays built in, perhaps waiting for confirmation that a mechanical part responded properly (e.g. gear doors opened, then uplocks released, then hydraulic pressure routed to hydraulic actuators, then gear shows locked in position, then hydraulic pressures released). It is possible one thing glitched or failed, which started a brief timer, which then commanded the other system to go to OFF electronically. This seems to me quite unlikely, but the level of hardware and software complexity can cause some weird things.

4) Moving those switches becomes quite automatic after a while when you shut down engines. The checklist will have a bunch of things before it, e.g. set the parking brake, establish electrical power from the ground or from the APU. Then when shutting down the engines the pilot moves one then the other switch. If there was a reason, no matter how faulty, for one of the pilots to decide to shut down one of the engines, I can see the "muscle memory" coming into play. This inadvertent action seems extraordinarily unlikely, but I have seen inexperienced pilots do some unexpected things in a crisis.

5) The latest report is not at all conclusive, but it smells like the murder/suicide scenario if the report is not significantly incorrect. I don't know though why the offender would flip the switches back to ON. Off is off even for a moment, and then a restart will take minutes. There's no logical deception or technical reason to move the switches back to ON.