The black boxes from Air india disaster.

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DaveReading

Don't suffer fools gladly (must try harder!)
Location
Reading, obvs
Or maybe the locking mechanism wore over time if constantly used?

Maybe, but the issue highlighted in the SB concerned faulty installation, rather than wear.
 

Bonefish Blues

Banging donk
Location
52 Festive Road
1:09:40 as I posted

Thanks, I didn't notice the time.

I just listened to that. The pilot did not say that the switches moved themselves. He says that he noticed that his 737 fuel switch locking mechanism wasn't operational as they were taxiing so they returned to the jetty to get it fixed. That was the issue that was the subject of the notice to operators in 2018.
 

DaveReading

Don't suffer fools gladly (must try harder!)
Location
Reading, obvs
I just listened to that. The pilot did not say that the switches moved themselves. He says that he noticed that his 737 fuel switch locking mechanism wasn't operational as they were taxiing so they returned to the jetty to get it fixed. That was the issue that was the subject of the notice to operators in 2018.
In normal operations the switches are only operated twice during a flight - on engine startup and shutdown.

I can't see any situation where a switch fault would become apparent when taxying to the runway for takeoff, other than inadvertent/uncommanded movement and resulting engine shutdown (a scenario foreseen in the SB).

This happened on a 747, by the way, not a 737 - though the same considerations apply.
 

Bonefish Blues

Banging donk
Location
52 Festive Road
Here's the extract from the Special Airworthiness Information Bulletin in 2018:

The FAA recommends that all owners and operators of the affected airplanes incorporate the
following actions at the earliest opportunity:
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.

That was the check.

It would be hard for any pilot to miss a defective switch for very long, but as said, it could not be checked whilst taxiing so the captain's account doesn't make sense as he told it.
 
Speculation is human nature.

It gives us something to talk about.
 
Here's the extract from the Special Airworthiness Information Bulletin in 2018:

The FAA recommends that all owners and operators of the affected airplanes incorporate the
following actions at the earliest opportunity:
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.

That was the check.

It would be hard for any pilot to miss a defective switch for very long, but as said, it could not be checked whilst taxiing so the captain's account doesn't make sense as he told it.

If the locking mechanism was faulty then there was nothing to prevent the switches from being turned which could happen during taxying.
 
What I don't get is that you think that there would be some kind of a warning. When you get into your car and turn the ignition on you get hand brake, seat belt and door warning lights. If you shut your computer down whilst a programme is running you get a message to say that you haven't closed it and are you sure you want to shut down. So something critical like fuel to the engines you would think there would be a warning of some kind?
 

Bonefish Blues

Banging donk
Location
52 Festive Road
If the locking mechanism was faulty then there was nothing to prevent the switches from being turned which could happen during taxying.

The switches do not turn. As said earlier, the pilot would have used both switches in turn on start-up. Perhaps he embroidered a bit for radio, or his memory of 6-7 years ago may have been flawed. See also my post below regarding the ergonomics & operation of the switches.
 
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Bonefish Blues

Banging donk
Location
52 Festive Road
What I don't get is that you think that there would be some kind of a warning. When you get into your car and turn the ignition on you get hand brake, seat belt and door warning lights. If you shut your computer down whilst a programme is running you get a message to say that you haven't closed it and are you sure you want to shut down. So something critical like fuel to the engines you would think there would be a warning of some kind?

That is why the switches are positioned as they are and why they are both spring loaded and have metal detents. It requires a specific reach behind the throttles and conscious operation - and it is impossible to operate both at the same time. They are designed to avoid their accidental operation.
 

DaveReading

Don't suffer fools gladly (must try harder!)
Location
Reading, obvs
What I don't get is that you think that there would be some kind of a warning. When you get into your car and turn the ignition on you get hand brake, seat belt and door warning lights. If you shut your computer down whilst a programme is running you get a message to say that you haven't closed it and are you sure you want to shut down. So something critical like fuel to the engines you would think there would be a warning of some kind?

I think pilots are given some credit for common sense. The switches are used at the end of the flight to shut down the engines, and it's assumed that they will very rarely be used at any other time.

It would be a bit like having a warning placard on the control column saying "Don't keep this pushed fully forward for any length of time or you'll hit the ground". Pilots are assumed to know when to do and when not to do things.
 

markemark

Veteran
The stop/start of the fuel is the correct procedure to an engine failure (stall, fire etc). Apparently something pilots are trained to immediately and quickly akin to a reflex. Is it conceivable that there was a false warning for the engines and the pilots did what they’re trained to automatically do and restart them?

The transcript doesn’t tie in with that but I’m not putting too much weight on what we know so far as it’s two sentences out of 5 minutes. There’s a huge amount of dialogue we haven’t read, nor the intonation it was said (screamed, queried, muttered etc).

It’s all very unlikely, but before we blame the death of hundreds on a pilot (and as above potentially the wrong pilot) I’m sure the investigators will be exhaustive in their investigation.
 
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