Air India 787 crashes on take off 8

[LittleInch]

A full 787-8 has crashed shortly after take off in ahmedabad.

Basically barely got off the ground then look like its trying to land in this video.

Air India ordered to carry out ‘additional maintenance actions’ on Boeing 787-8/9 fleet – as it happened

India’s ministry of civil aviation orders airline to carry out safety inspections on fleet with GE Aerospace GEnx engines after crash of flight 171

www.theguardian.com

Specualtion that they pulled flaps up instead of gear up and basically didn't have enough lift so it looks like a gentle stall right into a built up area.

Looks to be flaps up, slats/ nose flaps down and gear down which is very odd.

 

[Alistair_Heaton]

Cockpit video has always been apposed by various western pilot unions.

The long length cockpit voice recorder's are still apposed mainly in the USA.

Personally I really don't care...

The knee jerk imposition of additional medical checks is more of a concern.

 

[LittleInch]

Cockpit video has always been apposed by various western pilot unions.

The long length cockpit voice recorder's are still apposed mainly in the USA.

Personally I really don't care...

The knee jerk imposition of additional medical checks is more of a concern.

Why?

Surely it's good for the pilot community to know what happened rather than pure guess work or speculation.

 

[TugboatEng]

If the FDR is logging at 1hz a simultaneous movement (a few ms of separation) may appear as one switch moved after another or that ms split straddles a measurement point.

 

[LittleInch]

If the FDR is logging at 1hz a simultaneous movement (a few ms of separation) may appear as one switch moved after another or that ms split straddles a measurement point.

True, but equally it could mean the switches were moved one at a time 1.9 seconds apart.

Not sure what is to be gained by thinking these were "simultaneous". They were close enough that both engines basically shut down at the same time, hence no visible yaw.

The issue of timing for me is crucial. If this was indeed a deliberate act to crash the plane then three seconds after lift off was spot on. Not too early so that it was possible to abort / land the plane on the runway or inside the airport, but not too late so that the landing gear was still down creating drag and not enough time / altitude / speed for any APU to start or relight of the engines if fuel control switches moved back to run.

IF it was deliberate it was actually well planned and thought out.

If it was not designed to happen then it was one of the Swiss cheese holes aligned. Five / ten seconds earlier or five , maybe 10 seconds later you might not have had such a total disaster.

 

[TugboatEng]

The importance of the simultaneous switch is that it may be an indication of an intentional or unintentional action. If the locks were not in place and a pilot accidentally brushed the switches that would be nearly simultaneous switch while lifting and operating each switch intentionally may take more time.

 

[BrianPetersen]

Having watched this type of switch being actuated on video, roughly a second apart looks about right for what one person doing each switch one at a time would take.

 

[MintJulep]

Here's NM-18-33 about the fuel cutoff switches, and the Honeywell datasheet for the switches.

I don't understand the statement
"The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel
control switches were installed with the locking feature disengaged."

Looking at the datasheet, I don't see any way to "disengage" the pull-to-unlock feature as part of installation.

It looks to me like the pull-to-unlock is built into the switch by part number. If switches with the right part number don't have the feature, that suggests that Honeywell messed up.

 

[TugboatEng]

They datasheet does mention silver alloy and gold plated contacts but doesn't explain which switch has what type.

It also does not list the minimum switching current. This is an extremely important bit of information for digitally controlled systems. I usually see 50mA for silver alloy contacts and 5mA for gold plated. Neither are rated for the very high impedance inputs often seen with digital controls. What is the current through the switch?

Switch data sheets can be very misleading as switches with gold plated contacts will often have current ratings of 3-15 amps. That's because under the gold plating is a silver alloy contacts. However, currents over 30 mA will flash off the gold plating and now the switch no longer retains it's low current switching reliability.

 

[Roga50]

I love when the lawyers get involved....
(from the datasheet that MintJulep posted):

PERSONAL INJURY
DO NOT USE these products as safety or emergency stop devices or in any other application where failure of the product could result in personal injury
Failure to comply with these instructions could result in death or serious injury.

 

[Alistair_Heaton]

The only thing special about these switches is the price tag.

Not that I think this is an issue here, but counterfeit parts is relatively common in some cultures and areas of aviation. The fuel pump on a piper tomahawk is off a car. The data plate is just riveted onto the replacement pump costing 50$ instead of the piper one at 600$ this is 2003 prices.

 

[JohnLloydJones]

The only thing special about these switches is the price tag.

... and MTBF and rated temperature range, I would guess.

 

[Alistair_Heaton]

They are the same as you will find in a range of military hardware. And industrial applications. Trains have them, boats use them...

Once something is certified unless there is a cost saving or weight saving it will be used forever more. It wouldn't suprise me if the AOA vane sensors on the 787 are the original ones from the 747.