So, I think this video too shows a prototype aircraft flown by extremely experienced test pilots.

From memory- production aircraft at an airshow.
As the Admiral mentioned- an aircraft with absolute minimum load (No cargo, No Pax, barely any seating etc, and minimum fuel load ). Hence, very, very high thrust to weight ratio...

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Grant
Darwin NT

another video from the airport fence:

https://www.youtube.com/watch?v=7OOdki6gXKY

There is a "tale-off configuration incorrect", but this doesn't prevent a pilot trying to take-off with the flaps incorrectly set.
Take-off is achieved once the wings are generating enough lift, and once flying climb should be possible. Unless the engines stop generating power, or the flaps are retracted too early.
Several things, none good, go through my mind:
Pilot retracted the flaps instead of the undercarriage.
Dual engine failure - all civil airliners are rated to take- off at max load on one engine (assuming a twin engine plane like a 787.
Big bird strike on both engines causing instant loss of power. Generally smoke and/or flames will be seen coming forom the enines, which is not visible in the video clips I've seen.
I hope this helps your understanding.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

another video from the airport fence:

https://www.youtube.com/watch?time_continue=6&v=7OOdki6gXKY

Yeah, it took off OK, looked as though it was climbing OK, then just started descending and kept descending till it hit the ground.
Stall? No sign of change in AoA (Angle of Attack). Reduced power from both engines? (no sign of Yaw or rudder to offset asymmetric thrust). Or the flaps were retracted when the landing gear should have been retracted?
CVR (Cockpit Voice recorder) & FDR (Flight Data Recorder) data will be very interesting to see.

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Grant
Darwin NT

Thanks for that video. It's a bit grainy but does look as if some flaps were deployed and there's no sign of multiple bid strikes.
Couldn't say if the flaps were correct for a 'hot and high' take- off, but the fact that it was flying suggests adequate; this points me to thinking sudden loss of power, either commanded or uncommanded.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Not all stalls result in a high AOA some can appear to be very flat for a few hundred feet, then suddenly one corner of the aircraft dips... Not to bad if there's enough of a gap between aircraft and ground.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Couldn't say if the flaps were correct for a 'hot and high' take- off, but the fact that it was flying suggests adequate;

Bob claimed 37°C is not 'hot' and Ahmedabad Airport is situated almost at sea level: 58 m (189 ft).

Strange accident; considering this is a major flag carrier; member of Star Alliance. Air India's previous total loss was 40 years ago, caused by a bomb (Sikh terrorists). The last catastrophic accident due to a defective plane (resp. pilot error, not noticing a stuck artificial horizon) occurred almost 50 years ago.

Pilot retracted the flaps instead of the undercarriage.

Going into totally uneducated conjecture mode, some of my guesses are:

• Yep, copilot pulled the wrong lever;
  
• Incorrect takeoff configuration (insufficient or no flaps) and the alarms ignored;
  
• Overloaded aircraft for too short a runway;
  
• Engine thrust set too low or even not adjusted from their previous airport;
  
• Too short a runway for the weather conditions;
  
• Pilot distraction/confusion;
  
• Mechanical/systems failure.
  

Note that airport altitude is not a problem (it's at sea level). However, high air temperature and high humidity might be... Also, if the wind was adverse for takeoff. Those three factors reduce the available lift...


A worryingly unexpected catastrophe...

And why-oh-why are there not sterile areas along the takeoff/landing paths to allow for a non-disastrous emergency landing?

One to watch for what happened and why...


Fly safe folks?
Martin

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See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

• Overloaded aircraft for too short a runway;
  
• Too short a runway for the weather conditions;
  

Ahmedabad's runway: 3,500 m (11,500 ft) should be sufficient for a fully loaded B787. I also assume on a route length at just half the B787's max range, you can't overload the plane with cargo and baggage. Weather looked fair as well.

The flaps vs. gear is unlikely as the controls arr in different areas, flaps on the copilot side of the "engine controls" binacle, while the undercarriage is central on the upright panel. For once good control separation.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

They took off, so flaps & power settings were ok if not correct
Distraction/ confussion - a good starter for 10, along with some sort of failure.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

It is extremely perplexing.

The aircraft was able to take off and was climbing. Then it started to descend, and kept descending. The only way that will occur as far as i can figure is due to reduced lift.

Lift is a result of AoA, and aerodynamic lift which is dependent on airspeed & wing configuration and atmospheric conditions.
Because of the distance and angle of the view from the camera, it's hard to be sure, but there doesn't appear to be any change in AoA prior to the aircraft starting it's descent (or afterwards).

Once an aircraft leaves the ground, it is still under the effects of ground effect, so if it has insufficient lift after climbing out of the ground effect, it will then descend again- that did not happen here. The aircraft left the ground and appeared to have a positive rate of climb (it wasn't just climbing, but climbing at or greater than the minimum safe rate of climb).
Once a minimum rate of climb has been established, the undercarriage is retracted, flaps & slats are retracted, and the aircraft continues to climb.
The ADSB data we have is spotty, but the aircraft reached 675ft and 174kt.

There were no storms about, so the odds of a massive sudden downdraft are non-existent, and the aircraft didn't suddenly loose altitude, it was more like coming in for a landing- a gradual controlled decent.
There doesn't appear to be any puffs of smoke, flame or anything from either engine at any time prior to it starting it's descent, so bird strikes on both engines impacting their power output are unlikely.
Electrics/hydraulics issues making it impossible to retract landing gear, affecting flaps/slats operations?

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Grant
Darwin NT

Flaps, 0, 1, 5, 15 ...
Video I have seen of the ground roll it is very obvious the flaps are less than 15. Flaps 1 the video wouldn't be able to see.

Video I have seen the ground roll is long but not excessive. Were they using a power de-rate for takeoff thrust?

Question does the CAS only alert if the flaps are up when takeoff power is selected? Or does it alert if they are set less than what the FMS calculates is required?

Question was the correct data input to the FMS so it would give the correct settings?

Question did the PF reduce power from takeoff to the climb or cruise detente before the gear was up?

Question was positive rate not called out hence the gear remained down?

Question was the fuel system mismanaged?

Then the questions become mechanical issues and the mayday call points to such a possibility.

We will have to wait for the FDR and CVR readout.

Seat back videos are a grade 1 reliability issue with many airlines and aircraft types, but not working isn't a safety issue, unlike overhead lockers.

But the air conditioning also wasn't working which indicate an electrical problem.

Now what if the main electrical distribution system in the aft electrical equipment bay had a total failure?

No power to the fuel pumps would be a big problem for starters and even though the engines can still syphon fuel at that point of takeoff they'd never syphon enough to produce the power needed to get the plane into the air not to mention the other systems that would go down such as flying by wire.

Then there's the single survivor comments about a loud bang happening just before the plane became a glider.

All just things to consider.

No power to the fuel pumps would be a big problem for starters and even though the engines can still syphon fuel at that point of takeoff they'd never syphon enough to produce the power needed to get the plane into the air not to mention the other systems that would go down such as flying by wire.

On PPRuNE, amongst all the rubbish posted by the ignorant, several qualified people have posted that suction feed is sufficient to keep the engines fed during take-off.
And more power is required during take-off than during the initial climb.

Then there's the single survivor comments about a loud bang happening just before the plane became a glider.

Unfortunately there are probably as many different versions of that quote as there are posts about it.
One of the earlier ones i read, the quote was long the lines of a bang shortly before he ended up out of the aircraft- which i took to indicate that the tail struck the building shorty before the aircraft broke up and he ended up on the ground. And then there are quotes about him jumping out of the emergency exit, and others about him not knowing how he ended up on the ground.
Unfortunately, there's way too much noise to place much faith in anything posted about what he said or did/happened to him, other than he survived the crash and was helped by others to an ambulance.

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Grant
Darwin NT

On all aircraft, the engines have mechanical fuel pumps, during critical manoeuvres, like take-off and landing, the backup electrical fuel pumps are switched on, and would be switched off after reaching a safe altitude, usually about a 1,000 ft above the runway height.

Then there's.

An leading aviation expert has put forward the bombshell theory on what caused the Air India flight to crash 30 seconds after take off.

An leading aviation expert has put forward the bombshell theory that the co-pilot on Air India flight AI171 pulled the plane’s wing flaps instead of retracting the landing gear, causing the plane to crash.

Commercial airline pilot and YouTuber Captain Steve, who analyzes plane crashes and close calls, gave his theory on the incident which killed 241 people on board.

The London-bound 787 Dreamliner began losing height moments after take-off and crashed in a fireball over a residential area in the Ahmedabad, Gujarat.

Steve said he suspected there had been an exceptionally simple error in the cockpit when the co-pilot was asked to retract the landing gear, with devastating consequences......

[deleted... same info as Wiggo's]

But the air conditioning also wasn't working which indicate an electrical problem.

I do not believe these claims by a passenger of the previous flight from Delhi.

Bob wrote:

I've flown in a frw 787 and wouldn't rate the hvac system as good, perhaps mediocre...

I think, a plane standing in the sunshine on the tarmac in Ahmedabad for an hour in 37°C (99F) ambient air temp... would quickly heat up to unbearable conditions without air condition; leading to many (seniors... children) passengers collapsing quickly. It was eventually uncomfortably warm or stuffy for whatever reasons, but I can't believe air conditioning was 'not working' at all; thus an electrical problem. I can't believe a captain would depart for a long range flight with a faulty air conditioning. They tend to even return to their departure airport, hours in flight, if a too large number of toilets malfunction.

On the other hand... Air India isn't a praised airline either... like e.g. competitors from U.A.E., Singapore...

The electrical system of such aircraft is multifold redundant; many busbars, fed alternatively by APU, engine generators. It's almost impossible all electric busses will fail at once.

Now what if the main electrical distribution system in the aft electrical equipment bay had a total failure?

In an eleven years old B787? Extremely unlikely.

Sigh. There is an "expert" that has said from audio that the RAT was deployed. If true, what are the ways the RAT gets deployed?
1) Push Button
2) double electric failure on flight deck
3) double hydraulic failure (engine pumps)
4) quadruple hydraulic failure (electric pumps)
5) engine failure plus hydraulic failure

My thought is what the heck could have happened between the ground checklist where all these systems are verified and the length of the flight?

We need the black box readout.