Re: OT: air india crash

Er no. Preliminary report says both engines fuel switches turned to cut-off and then were restored to on again. Too late to make enough difference.

After one cockpit voice asked 'why did you turn the fuel switches off to which the other replied 'I didn't'...

Well cannot is a very definite and exclusive word.

Not quite, The engines take about 10 seconds to spin down. The rest is correct.

Unlikely, plus why would anyone touch a two fuel cut of switches that were already set correctly to provide fuel for take off? The switches cannot be accidentally moved and pilots have said (almost) impossible to switch both at the same time, so two actions to move both.

They are switches used at the end of every flight to cut fuel when the aircraft is parked. The pilots were trained and experienced.

The why and who, and maybe how, is just subject to speculation at this time.

Because mostly what they are intened for is an engine failure, especially a fire.

In that case a master isolation switch - like a car ignition - is handy to ensure no fuel is delivered.

AIUI it needs a lift and pull type action to move them. Once in place they are essentially locked.

Conceptually like a car handbrake [used to be]

On an aircraft both pilots had over 1000 hours on?

I would guess that the switches were not unmarked, and both pilots were trained and experienced with this aircraft.

The other pilot responded that he “didn’t”, according to the report.

The switches were then moved back to their normal position, which automatically started the process of relighting the engines.

One of the engines was in the process of regaining power at the time the aircraft crashed. The other was relit but was not yet regaining thrust.

I can see that you might want to turn one engine off if it caught fire, but *all* of them? During take-off, would it be better to keep the fuel on, risking a fire, or turn it off, risking almost certain death from a crash due to lack of thrust/lift?

Presumably the data recorder will contain information about the engines to determine whether there was an incident which would have warranted turning the fuel off. I imagine that is still being investigated and so has been excluded from the preliminary report. Likewise I imagine the investigators know who said what on the flight deck because the pilot's and co-pilot's voices are recorded on different, identified tracks on the cockpit voice recorder - they are being deliberately vague to avoid pointing a finger at either one of them, for the sake of their families.

Do all aeroplanes, worldwide, use the same convention (probably the American one of up=on) irrespective of the country which owns/operates the plane, to avoid this indecision?

I wonder if at some stage in the future, CVRs will start to record video of the pilots to show who did what - who turned the fuel to cutoff and who turned it back on (were they the same person or different ones).

On the other hand, would the interlock logic (electronic as opposed to physical barriers) allow fuel to *all* the engines to be turned off during take off? If a fire/bird-strike/blade-fracture occurs during takeoff, is it better to make certain that fuel cannot accidentally be turned off to the wrong engine (Kegworth), by disabling the second fuel cutoff switch once the first has been turned off and until the first (wrongly turned off) is providing thrust again. Or maybe disable fuel cutoff unless a fault (eg fire) is detected in an engine.

Not a simple solution whatever you do, but I wonder if the Indian crash will result in any changes to the logic that links the switches to the actual cutoff valves. Time will tell.

In general do planes have enough power to take off on one engine, albeit with a lot of yaw that needs to be corrected very quickly, if a fault occurs in the seconds after rotate?

Sequence of events, this chap usually does the best coverage of plane crashes

Yes. AIUI the yaw correction is automatic up to a point

One engine takeoffs are recommended if the aircraft is above V1 (no going back speed)

Apparently they use the same switches in 737s and there was a problem there of some switches being fitted without the safety mechanism - leaving them prone to accidental switching.

Strain gauges on the undercarriage to distinguish between 'on the ground' and 'in the air'? As soon as there is no weight on the undercarriage, 'airborne' rules could take over. I'm speculating wildly!

Would you want to cut off all engines in the critical first few seconds of takeoff? Is it better to cutoff and restart than to keep the fuel flowing even though the engines are on fire *in the situation where cutting off thrust and waiting for the engines to restart would almost certainly be fatal*?

What, two switches suffering a similar jam, at the same time?

Not strain gauges, as is commonly understood. Sensors that measure whether the wheels have compressed the struts, I think

You don't waste time and money compensating for a problem that has never ever occurred before and looks likely can never occur again.

But it would not be hard to do this.

The final report wont be out for 18 months.

The interim conclusion is that one of the pilots almost certainly deliberately crashed the aircraft, for reasons unknown.

It has been confirmed that this aircraft could have continued to climb on one (working) engine, with the undercarriage down and the flaps withdrawn.

Some of the controls were recoverable, and the flap control was set to

They are physically adjacent. I agree, its a very long shot indeed.

or excesive vibration?