Posts by user "Europa01" [Posts: 14 Total up-votes: 0 Pages: 1]

Simultaneous failure of both engines has to be very far down the probability scale particularly with no external signs. Surely unthinkable that thrust was retarded but what would explain the beginning of the sickening loss of climb at about 10 seconds after rotate?

Assuming the reported Mayday message is correct then a final message indicating a hopeless situation has to be a possibility.

Possibly the Captain did correctly perceive the information on the status of the aircraft

Possibly he did correctly comprehend the situation.

Possibly he did project the situation into the future

(Endsley &Jones)

The requirement to lift the cutoff switch out of the detent before moving it is an important point. However, those switches are close together and unless the the detent requires significant force I suggest that they could be operated together with one hand if that was an intentional action.

wonkazoo #963 Thank you for such a clearly reasoned and thoughtful post. Taken together with Capn Bloggs \x92 reasoning on thrust levers in his #955 I\x92d like to think that pet theories would be tested against these two posts from this point onwards before hitting the keyboard (although I suspect they won\x92t be)

Yes. Thank you tdracer. All those postulating TCMA / FADEC faults please read and understand this clear explanation.

Then, ask yourselves which extraordinarily low probability bundle of previously unrevealed faults could spontaneously manifest themselves on both engines simultaneously.

Also ask yourselves why these faults manifested at that critical phase of flight and not during taxiing or take-off roll when some of the TCMA sensors would have been primed.

Yes. Thank you Capn Bloggs. All those postulating flaps or preflight input errors please read, understand and ask yourselves does your theory pass this test? ( Bloggs Test 1)
Also please read the good Captain’s much earlier post along the lines of - if thrust runs back to idle wouldn’t the PF / PM simply advance the thrust levers to firewall? (Bloggs Test 2)

Yes. Thank you tdracer. All those postulating TCMA / FADEC faults please read and understand this clear explanation.

Then, ask yourselves which extraordinarily low probability bundle of previously unrevealed faults could spontaneously manifest themselves on both engines simultaneously.

Also ask yourselves why these faults manifested at that critical phase of flight and not during taxiing or take-off roll when some of the TCMA sensors would have been primed.

Yes. Thank you Capn Bloggs. All those postulating flaps or preflight input errors please read, understand and ask yourselves does your theory pass this test? ( Bloggs Test 1)
Also please read the good Captain’s much earlier post along the lines of - if thrust runs back to idle wouldn’t the PF / PM simply advance the thrust levers to firewall? (Bloggs Test 2)

Assuming the reported Mayday message is correct then a final message indicating a hopeless situation has to be a possibility.

Possibly the Captain did correctly perceive the information on the status of the aircraft

Possibly he did correctly comprehend the situation.

Possibly he did project the situation into the future

(Endsley &Jones)

Yes. Thank you tdracer. All those postulating TCMA / FADEC faults please read and understand this clear explanation.

Then, ask yourselves which extraordinarily low probability bundle of previously unrevealed faults could spontaneously manifest themselves on both engines simultaneously.

Also ask yourselves why these faults manifested at that critical phase of flight and not during taxiing or take-off roll when some of the TCMA sensors would have been primed.

Happy to accept any challenge to my post. The SAIB refers to 4TL837-3D switches which are explicitly covered in the Honeywell data sheet I looked at (p16). Given that the SAIB was based on some shortfall in the locking mechanism it maybe that all these switches have been replaced by something with an improved specification since the SAIB was issued and I’d be very pleased to acknowledge that. Those who know facts what do you think?

Not looking over my shoulder here but I should add that I know and respect Honeywell switches. Those I have worked with are well designed and well made plus Honeywell incorporate improvements based on field experience. As posted by another contributor upthread I am puzzled by the odd ‘down’ = engine off configuration though.

The excellent #724 post by user989 really should be seen as the defining statement on what is currently known.

I’d like to add a complimentary test to user989’s logic on TCMA faults.

Regardless of whether the ‘aircraft on ground’ signal was incorrect after rotation it would have been correct during the takeoff roll. IF there was an unrevealed fault in a thrust lever position signal THEN why didn’t TCMA activate during taxiing or the takeoff roll?

Such a fault occurring spontaneously in just the few seconds after rotation is way way down the probability table. Such a fault occurring spontaneously on both separate (think ETOPS) engine control systems is surely vanishingly unlikely.

They may be out there but you’d have to ask if TCMA is implicated where are the lower consequence precursor events in the 787 fleet? These might be spurious TCMA action on one engine or faults with ‘aircraft on ground’ found during maintenance or engines not responding to thrust lever position and so on.

Change Analysis would ask what happened differently in the few seconds after rotation on this flight that separates it from all other 787 takeoffs and why at that particular time ?The interim report will provide some answers until then please let’s confine this thread to fact based technical discussion and debate.

Re-reading this I did briefly consider suggesting engine overshoot of thrust lever positions and FADEC shut down on N1 overspeed but that leaves a lot of WHY and WHY both engines questions so I dismissed it.

Unattributed reporting in newspapers needs to be treated with caution - especially from a newspaper like the Telegraph which it is fair to say is no longer the institution it once was.

They are usually such nice sharks.

What is known so far certainly does defy logic but I struggle with the brain fart idea. Firstly (noting that the initial report does not mention positive rate or gear up calls) I can’t see any action cue for the PM to do anything at all at the time the switches were moved to CUTOFF. If some sort of random disorientation action is postulated then you’d have to ask why did it occur at that critical moment and not 30 seconds earlier or 30 seconds later?

Secondly, I can’t be the only one who has operated a control and then perceived an unexpected set of visual, audible or physical responses from something unrelated and instantly thought WTF have I just done followed by an immediate re-check of that action? Although the initial report is notable for what it does not say I can’t see the flat denial of any action is what would be expected given the plethora of cues in that cockpit following the operation of the switches.