Posts about: "Human Factors" [Posts: 58 Pages: 3]

Just for the record, there is no system on modern Boeing aircraft to prevent the accidental retraction of flaps when too low or slow when airborne. You wouldn't even get a warning on Boeing aircraft that is related to Flaps, you'd eventually get one related to Low Speed or Stall. The Airbus has a safety feature called "Alpha-Lock" which physically stops the Flaps from moving when the AoA or speed? is deemed too low. But that's not a safety net for all flap settings, just the lowest for takeoff. It will save the day in 95% of situations though Mr Boeing (hint hint)

Takeoff config warnings and checklists may not have helped if the flap setting was not enough given the weight and conditions. A good handling pilot could recover from an incorrect flap setting (providing there's no obstacles to deal with), by gently lowering the nose allowing the airspeed to build up before resuming the climb. However, various human factors such as startle and over reliance on automation (my thrust setting must be good) will not help the situation.

In order of likelihood:

1.) Flaps moved instead of gear
2.) Incorrect Flap settings and inability of crew to recover from that
3.) Double engine failure
4.) Some electrical event that distracted them

Item 1) On the 787, is the gear lever on the main panel facing the flight crew, or on the centre console? I'd imagine they'd (flap and gear levers) need to be adjacent to each other for that to happen. All good points though.

TE Flaps are extended, flap gaps between the wing and the flap element are observable. This is not an aberration of the spoiler position, you can see the nacelles through the gap, and that means the flap can not be in the retracted position.

An error of the TE flap deployed position, say between flaps 5 or 15 is not going to cause a stall event.

The flap has not been retracted instead of the gear.

Double engine failure... India. birds, always a latent threat. No rudder deflection, no aileron deflection, so it's not a SE problem, any engine issue is affecting both engines.

Pitch control and roll is not compromised in the video. The crew put out a mayday, not sounding like an electrical fault or distraction.

any funerals near by?

Incorrect TO thrust setting would not present in the video as recorded. Low thrust results in low acceleration, and extended distance to rotate. after rotate, low thrust results in low climb rate, and can result in the crew over pitching where the aircraft has obstructions that the crew have to avoid. the video appears to show the pitch increasing at a point where the aircraft is already unable to climb, not the other way round. An outside possibility.

For survivors, any from the aircraft will be a miracle, and mainly from the rear of the plane near door 3 area, if any. Plane is still striking tank traps at 70m/sec +, high ANU, it's not a high survivability event. Occupants in the buildings along the flight path will have a high fatality rate as well. This is going to be a high toll event in the aircraft and on the ground. Bad day at VAAH. RIP.

EICAS take off config + master warn...

The RAT appears out. Little asymmetry at any point. It has the ingredients of dual engine loss, whether from bids, electronic or human error reasons we will soon find out.

I think because human error is more palatable than a yet unknown fundamental failing possible in 1100 B787s.

Behind the horror of this accident there will be people and organisations secretly discussing whether to boycott Air India or ground B787s.

In the meantime the majority of us are considering the horrendous human cost regardless of the cause being faulty pilots or faulty planes.

Question to Human Factors experts or pilots having experienced/witnessed that.

Disclaimer: I never flew something with retractable undercarriage, just flaps. I also acknowledge that under substantial stress, and especially panic, your lizard brain awakes and takes over your Einstein brain. But on the other hand less so in routine handlings before things go south.

So - my question: If you look at the 787 cockpit layout (google, YT, your picture), how can Flaps Up instead of Gears Up be executed? It is a totally different activation of arm muscles, hand muscles, fingers even when not looking what you do ("three greens no red" anyone?). I mean, I totally understand the mishandlig of the switches and buttons on the Vilnius B737 - taking out hydraulics instead of anti ice. Switches are close, switches are similar. But gears and flaps levers - I just dont understand why still many people here set this on the high probability list. I absolutely don't buy it. At least it would be on my possible causes on a list far, far down. Considering the deck layout on a 787.

Do I miss some physiological/psychological human brain factors?
Because some of the professionals seem to have written here - "quite possible" in real stressfull world. Maybe on some GA aircraft where flaps select is also sometimes on the front panel. But 787?

NB: I am still on the symmetrical and significant thrust loss hypothesis ~10s into the airborne time.

I was in the jump seat on a 747 as 3rd pilot many years ago. The Captain was PF and after the positive climb call the Captain called \x93Gear Up\x94 and the PNF selected and stated \x93 Flap 10\x94. The PNF immediately reversed the selection before anything actually moved \x85. It is totally possible.
However in this case, I don\x92t believe this was what happened. Let\x92s await the investigation.

The sequence and timing of events has me concerned & saddened. The crew were along for the ride on this one.

Having said that, nothing happens in isolation.
What could have been done to break the event chain? Delay departure until deferred maintenance items were resolved? Line pilots feel this commercial pressure daily. On Time Performance is the R in Regular Public Transport & companies with the best OTP win the marketing high ground & customer $$$ to go with it.
The MMEL/DDG says we can depart with certain defects, so we often do, given the above.

Command decisions reached by applying years of knowledge & experience are the last line of defense against commercial pressures. Saying NO is important. Slowing down. The art of push-back is a feature of Human Factors training for a reason. (I\x92m not suggesting the event crew failed to do this.)
Command decisions need to be supported by a healthy Company culture, & supportive Flight Ops management team, from the Chief Pilot down.
I hope the culture at Air India (& your company) embody those ideals.

Hmm. Not sure where the idea comes from the gear was partially retracted... I can't see any signs for it on the video, nor can I see a RAT. and just to say "some event" must have happened is not very helpful, is it? Of course "something" has happened, but the question remains what.

Would it not make more sense to assume there is no RAT if no RAT is visible?

Could it be that we as pilots are in general biased to find a technical reason, although we all know the vast majority of accidents are down to human error?

it\x92s easy to explain that a small feature is not shown on a single frame of a low quality video when there are also frames where something can be seen where the RAT should be. It\x92s much harder to explain the RAT-like sound clearly audible though the whole video. My money is on that the RAT was out, but it\x92s not a fact.

Deployed RAT doesn\x92t rule out pilot error, so no bias there.

I was not aware that we have granular ADS-B data from the a/c itself showing airspeed post rotation (rather than speed interpolated from GPS). Apologies if I have missed it. If it does show acceleration after takeoff I tend to agree with you.

In no particular order, here are some more thoughts on TCMA having caught up on the thread:

If you cut the fuel from two big engines at take-off power, there must be some delay before n2 decays below the threshold for generation (below idle n2), the generators disconnect and RAT deploys. GEnx have relatively long spool up/down times as the fan is so large (and would be exposed to 170+kts of ram air). Perhaps someone has a view on how long this would be, but I imagine it could easily be 10s or more between fuel cut off and RAT deployment. On AI171 the RAT appears to be already deployed at the beginning of the bystander video. That starts c. 13s before impact and around 17s after rotation. This does not prove anything except that the supposed shut down must have happened very close to rotation and could have happened just before rotation while the a/c was on the ground.

As a thought experiment, imagine if ANA985 in 2019 had decided to go around. The a/c rotates and is ~50 ft above the runway, suddenly both engines spooling down, very little runway left to land on and no reverse thrust available. I am struck by how similar this scenario is to AI171. This theory would require there to have been unexpected thrust lever movement in the moments before rotation - but plausibly one pilot moving to reject, followed by an overrule or change of heart - or even a simple human error such as the recent BA incident at LGW - could achieve this. This is perhaps more likely that any sensor fault that you would expect to only impact a single engine given the redundancy of systems.

Tdracer writes that a key requirement of TCMA is to identify an engine runaway in the event of an RTO, in order to allow the a/c to stop on the runway. This will have been tested extensively - it is a big leap to imagine a false activation could be triggered. It did happen on ANA985 but through a very unusual set of inputs including application of reverse (albeit this latter point may not be relevant if TCMA logic does not distinguish between the reverser being deployed or not).

Incidentally there is an assumption the TCMA software version in place on the ANA flight had already been patched and fixed on AI171. That probably is the case but I am not sure it is a known fact.

In summary I remain baffled by this tragic accident. I have not yet read anything that explicitly rules out TCMA activation and it remains a possibility due to the vanishingly small number of factors that could shut down two engines at apparently the exact same moment when they have fully redundant systems. Fuel contamination, for example, has typically impacted each engine a few minutes (at least) apart. I am also cautious (as others have pointed out) of a form of confirmation bias about Boeing software systems with four-letter acronyms.

In my mind the cause could equally well be something completely different to anything suggested on this thread, that will only become clear with more evidence. All of the above also incorporates a number of theories, i.e. that there was an engine shutdown - that are not conclusively known.

Thank you to the mods for an excellent job.

Would moving the levers to idle during t/o not engage RTO? I.e. we would see spoilers deployed and maximum braking applied if that were the case?

Or are you suggesting the levers moved back but not exactly to idle for RTO to kick in?

I was not aware that we have granular ADS-B data from the a/c itself showing airspeed post rotation (rather than speed interpolated from GPS). Apologies if I have missed it. If it does show acceleration after takeoff I tend to agree with you.

In no particular order, here are some more thoughts on TCMA having caught up on the thread:

If you cut the fuel from two big engines at take-off power, there must be some delay before n2 decays below the threshold for generation (below idle n2), the generators disconnect and RAT deploys. GEnx have relatively long spool up/down times as the fan is so large (and would be exposed to 170+kts of ram air). Perhaps someone has a view on how long this would be, but I imagine it could easily be 10s or more between fuel cut off and RAT deployment. On AI171 the RAT appears to be already deployed at the beginning of the bystander video. That starts c. 13s before impact and around 17s after rotation. This does not prove anything except that the supposed shut down must have happened very close to rotation and could have happened just before rotation while the a/c was on the ground.

As a thought experiment, imagine if ANA985 in 2019 had decided to go around. The a/c rotates and is ~50 ft above the runway, suddenly both engines spooling down, very little runway left to land on and no reverse thrust available. I am struck by how similar this scenario is to AI171. This theory would require there to have been unexpected thrust lever movement in the moments before rotation - but plausibly one pilot moving to reject, followed by an overrule or change of heart - or even a simple human error such as the recent BA incident at LGW - could achieve this. This is perhaps more likely that any sensor fault that you would expect to only impact a single engine given the redundancy of systems.

Tdracer writes that a key requirement of TCMA is to identify an engine runaway in the event of an RTO, in order to allow the a/c to stop on the runway. This will have been tested extensively - it is a big leap to imagine a false activation could be triggered. It did happen on ANA985 but through a very unusual set of inputs including application of reverse (albeit this latter point may not be relevant if TCMA logic does not distinguish between the reverser being deployed or not).

Incidentally there is an assumption the TCMA software version in place on the ANA flight had already been patched and fixed on AI171. That probably is the case but I am not sure it is a known fact.

In summary I remain baffled by this tragic accident. I have not yet read anything that explicitly rules out TCMA activation and it remains a possibility due to the vanishingly small number of factors that could shut down two engines at apparently the exact same moment when they have fully redundant systems. Fuel contamination, for example, has typically impacted each engine a few minutes (at least) apart. I am also cautious (as others have pointed out) of a form of confirmation bias about Boeing software systems with four-letter acronyms.

In my mind the cause could equally well be something completely different to anything suggested on this thread, that will only become clear with more evidence. All of the above also incorporates a number of theories, i.e. that there was an engine shutdown - that are not conclusively known.

Thank you to the mods for an excellent job.

No pilots shift the source of human error to designers/engineers. You can't get an error-free environment. To achieve safety you have to accept the possibility of errors and design to deal with them.

Tata group chairman (majority owner of Air India) N. Chandrasekaran had a TV interview with Times Now, an English-language news group in India. I haven't seen the full video (blocked from the USA but someone will surely upload to YouTube soon), but there are some summaries and quotes from the interview appearing on various US sites.

Below are some interesting quotes from an MSN article ( https://www.msn.com/en-in/money/tops...ys/ar-AA1GYiEZ ), including a claim that both pilots but especially the FO had more experience than previously reported:


“There are speculations about human error, speculations about airlines, speculations about engines, maintenance, all kinds,” he said. “But the fact that I know so far is this particular aircraft, this specific tail, AI-171 has a clean history. As for the engines, the right engine was a new engine put in March 2025. The left engine was last serviced in 2023 and due for its next maintenance check in December 2025. Both engine histories are clean,” he told Times Now. “There were no red flags or maintenance issues,” Chandrasekaran said. “Never been safety concerns raised, Dreamliners have been operating for a long time.”

“Captain Sabharwal had more than 11,500 hours of flying experience, the first officer Clive (Kundar) had more than 3,400 hours,” Chandrasekaran stated. “What I hear from colleagues is that they were excellent pilots and great professionals. So, we can't jump to any conclusions. I am told by all the experts that the black box and recorders will definitely tell the story. So, we just have to wait for that,”

Interesting what is not said. While Chandrasekaran enumerates some of the theories about the cause of the crash ("human error, speculations about airlines, speculations about engines, maintenance, all kinds,\x94) the only speculation he goes on to refute is maintenance of the engines - leaving the other possibilities still out there..

Extracting meaning from what is NOT said isn't even speculation, it's pure guesswork.

Plus, what on earth would you expect of 'the boss' but that he talks up the competence of his company?

In my 40 years of Aviation Engineering / Ops management we've seen an incredible conclusion to the post WW2 / jet age strive for air transport safety. IMHO it peaked about 10-15 years ago and now what we see are the vanishingly small / unpredicted modes of accidents, hyped up by the new media age. I wasn't a fan of Donald Rumsfeld but despite the piss taking, he was actually right about known and unknown unknowns. The latest very small number (statistically) of very tragic accidents either bring out things we thought we'd sorted years ago, human factors or infinitesimally small occurrence latent conditions that no-one of any sanity (or ALARP minded) could have predicted.

This may well turn out to be poor design, maintenance, pilot error or act of just sheer bad luck given the 787's overall hours (possibly underserved or deserved pass to Boeing on that one). It won't stop me getting on a 787 or flying in that region any time soon.

Nobody here could answer that, but since the authorities in India have said the recorders themselves are there and not going anywhere, I would guess that if any data has been downloaded and shared outside the country, it will be for specific analysis purposes - GE for example.

There's no credible reasons 'three former accident investigators' in the US would have any direct knowledge, and if any third party in the US has been provided access to data, it will have been on the basis that it is not shared. Even that I would doubt, since involved parties are far more likely to already be in India as part of the investigation.

On edit, and mindful of the Mods comments around the closing of the thread previously: I don't speak with any direct knowledge of accident investigations in India, only the UK - and even then with only one experience of civil aviation accident work. But I have been involved (in human factors as investigator and lead) in several UK incidents of scale, and have some familiarity with how these processes are constituted and work... there at least.