Civil Aviation Development & Discussion

[RCase]

3 points floating around :
1. Flaps setting given 37°C temp. Hard to discern from videos what was set. 0 or 5 or 10° . Hot weather reduces air density hence less lift, needs greater take off speed before rotation. 787 has an alarm if flaps left at 0
2. Gear down after take off - not clear how this contributed to the crash, it definitely increases drag but leading to stall right after takeoff doesn't seem plausible in this case. As a passenger I've experienced gear retracts on various similar ac much later than this flight was airborne. Needs hydraulics to work, which in turn needs engines to work normally.
3. Loss of thrust - both engines simultaneously remains a mystery. The videos are a bit low res, one can see a bit of dust spinning up behind the hot engine exhaust at the moment of take off and distortion due to refractive index change (mirage effect). A high resolution video can help determine at what moments thrust decreased and stopped based on hot exhaust decrease and consequent decrease of the mirage effect behind the engine/s. Not sure if any security cameras picked this up correctly - they aren't designed or set up for this.

From the videos, the take off seems normal. Sufficient thrust and rotation speed. The plane starts the climb and the initial climb seems normal. If the speed before rotation was insufficient, it would have dropped right away and not started a climb. Once air borne, if thrust was at same level. the aircraft would at least be flying at the same level or doing a sluggish climb. However, it seems like the thrust started dropping and the pilot was in a controlled glide downward with nose up. From the sequence of events, there wouldn't have been sufficient time to get the gear up given the sudden loss of power within a few seconds of being airborne. Even in routine takeoffs, it takes a few more seconds for the gear to be retracted up. (Only with fighters, you see the gear retracted almost immediately after being airborne and doing a steep climb).

[A_Gupta]

What Caused Air India 171 Crash, Mysterious Sound Before Impact
https://youtu.be/SbDJjgN7Xbo?si=Feon9ulNiHu5If0b

The sound suggests that the RAT deployed. "A Ram Air Turbine (RAT) is an emergency power source on certain Boeing aircraft, like the 777 and 787. It deploys automatically in certain situations, such as engine failure or total loss of electrical power."

[saip]

Anyone seen Akas Vatsa's video? He seems to claim that he traveled on the same aircraft from Delhi and deboarded at Ahmadabad because " the ac was not working". What is the truth?

[LakshmanPST]

Anyone seen Akas Vatsa's video? He seems to claim that he traveled on the same aircraft from Delhi and deboarded at Ahmadabad because " the ac was not working". What is the truth?

When on ground, AC does not work many times...
Also in-flight system of Air India always turns on after Take-off only...
It hardly proves anything...

[Dileep]

Folks, remember that the heaviest lift penalty is right at rotation among all the flight regimes. Speed is lowest, and drag is highest. If the aircraft rotated properly, and gained some altitude before gliding down means that neither flaps, nor landing gear affected the flight. The flight was normal till at least 400+ feet altitude. It is clearly a loss of thrust.
Bird strike can be eliminated. No smoke, fire or debris seen in the exhaust. A catastrophic failure due to bird strike begins with the fan blades being broken. If they are not broken, then the bird is minced to paste, and pass through the engine with no issue. This is actually tested for engine certification. If they are broken, you will see the effect in the exhaust. Impossible to miss even in the grainy video.
So, it must be dual engine shutdown only. How that is possible in normal scenarios? Quite impossible.
Anyway, FDR/CVR are available, and all the debris are also available. AAIB and NTSB will do a good job of investigation, and at some point we may know what happened. Or may not.

[arvin]

If signal lost at 625 ft, then APU also gone bad ?? Waiting for probe to confirm if RAT was deployed. If it indeed it was then its full power failure onboard.
787 also has Main battery and APU battery. So multiple redundancy here.

[williams]

If signal lost at 625 ft, then APU also gone bad ?? Waiting for probe to confirm if RAT was deployed. If it indeed it was then its full power failure onboard.
787 also has Main battery and APU battery. So multiple redundancy here.

What about the 2016 software controller bug? Is it possible some sort of maintenance oversight/glitch caused another bug to popup that caused massive electrical failure?

[Amber G.]

He was apparently in seat 11A...

[srin]

I saw one video which said that pilots could have retracted flaps by mistake instead of landing gear

[Cyrano]

FWIW...

https://prospect.org/economy/2025-06-12 ... air-india/

[SRajesh]

There is a video explanation from an American Boeing Pilot (who is still flying planes) explaining probably a human error.
Hi theory is : as the plane goes up from runway (2-3 degrees nose up and about 50 -75 feet up), the person who is flying says gears up.
And the co-pilot then leans forward and grabs a lever to activate the undercarriage to be lifted up. This makes the plane more aerodynamic as it is picking up speed and gets to about 10-12 degrees up and keep climbing.
His theory is Human Error : the Co-Pilot instead of grabbing the lever to pull under carriage up grabbed the lever to pull the flaps in. This resulted in loss of lift added with more drag from the undercarriage. The Pilot tried his best to get more lift but unsuccessful and the plane just glided down and crashed as there was no lift.
He had no time to dump fuel as well.
Now this is all speculation and theory
We have to wait for the investigation report mind you.

[SRajesh]

Any pilots on the forum please explain if this is plausible??

[ashthor]

There is a video explanation from an American Boeing Pilot (who is still flying planes) explaining probably a human error.

We have to wait for the investigation report mind you.

The pilot had already called a mayday...are they trying to deflect attention from boeing?

[SRajesh]

^^^Looks like it
The YouTube is getting flooded with this Anal Cysts coming as pilot error/human error

[sanjayc]

Sole survivor:

Ramesh said that soon after the flight took off from the runway, lights started flickering inside the aircraft before it rammed into a building. He added that the section of the aircraft he was in remained grounded and, unlike the rest of the plane, did not crash onto the roof of the building.

https://www.hindustantimes.com/india-ne ... 65081.html

[gakakkad]

There is a video explanation from an American Boeing Pilot (who is still flying planes) explaining probably a human error.
Hi theory is : as the plane goes up from runway (2-3 degrees nose up and about 50 -75 feet up), the person who is flying says gears up.
And the co-pilot then leans forward and grabs a lever to activate the undercarriage to be lifted up. This makes the plane more aerodynamic as it is picking up speed and gets to about 10-12 degrees up and keep climbing.
His theory is Human Error : the Co-Pilot instead of grabbing the lever to pull under carriage up grabbed the lever to pull the flaps in. This resulted in loss of lift added with more drag from the undercarriage. The Pilot tried his best to get more lift but unsuccessful and the plane just glided down and crashed as there was no lift.
He had no time to dump fuel as well.
Now this is all speculation and theory
We have to wait for the investigation report mind you.

Not a pilot . The most reliable YouTube channel on air crash is mentor pilot . He is a veteran instructor pilot and air crash investigation expert . He does Swiss cheese analysis of all aircrashes on his channel since 1970. He has a great video on this yesterday. Requests people to not speculate . He goes over that theory . Says it's one possibility not there is no evidence that happened . Moreover the wing flap levers and the landing gear livers look and feel very different. They are designed that way because such errors have happened in the past .

[A_Gupta]

Ahmedabad plane crash: Flight data recorder recovered from rooftop, confirms AAIB
The Aircraft Accident Investigation Bureau (AAIB) on Friday confirmed that the Digital Flight Data Recorder (DFDR), commonly known as the black box, was recovered from the rooftop of a building at the Ahmedabad crash site — not from the wreckage shown in widely circulated videos.

"Contrary to some reports, the video recorder being circulated is not the DFDR. The black box was located on a rooftop and has been recovered. Work began with full force immediately," AAIB said in a statement.

https://timesofindia.indiatimes.com/cit ... 799226.cms

[tandav]

Snip: the Co-Pilot instead of grabbing the lever to pull under carriage up grabbed the lever to pull the flaps in. This resulted in loss of lift added with more drag from the undercarriage.

Theory 1: Pilot Error Flaps up instead of Landing Gear Up, leading to loss of lift due to increased drag from landing gear and decreased lift from Flaps
My Comment: there is no discernable change in flap configuration on take off as seen from videos from ground. It is not possible that Pilot started with no flaps without lots of alarms going off in cabin. Sabotage Angle: A circuit breaker was pulled beforehand before take off preventing not only alarms but also misinforming the pilot that the flaps were set when infact they were not. Pilots took off assuming the flaps were ok and were probably puzzled why the plane took the whole runway to take off. But take off they did without flaps

Theory 2: Flaps set properly and everything was fine until rotation and climb to 600 ft ASL . The both engines quit simultaneously due to lack of fuel due to potentially sabotage/failure of fuel valves etc. Engine gone == all hydraulics were gone, the bang reported by the survivor is the auto deployment of the Ram Air Turbine (RAT) for emergency power only for critical equipment, note the whistle of the RAT in original video taken from balcony showing the starboard side (right side) of the plane. But with no power and no ability to do anything the plane went down within 1.5km of end of runway. Falling quite gently in the z dimension of 460 ft/min = 2m/s (which is like falling from 3ft height) showing Pilot professionalism however with a forward speed of 160 knots (140-150 knots is take off speed depending on load and air temperatures) after impact with buildings. The resultant fireball caused all the deaths... most would have survived if there was no fuel on board which unfortunately exploded on impact. Pilot could not dump fuel either given that the entire matter ended in 20 seconds post loss of control.

https://timesofindia.indiatimes.com/tec ... 801263.cms

[srin]

I don’t understand the conspiracy theories. Having watched dozens of Air Crash Investigation episodes, there are only a few occasions where malice caused a crash. The Swiss cheese theory says there are usually a lot of process failures that leads to crashes like this, and not a single cause.
Hope the black boxes have survived.

[Mukesh.Kumar]

I don’t understand the conspiracy theories. Having watched dozens of Air Crash Investigation episodes, there are only a few occasions where malice caused a crash. The Swiss cheese theory says there are usually a lot of process failures that leads to crashes like this, and not a single cause.
Hope the black boxes have survived.

One black box recovered.

[chetak]

Not authenticated but some sources say that this was the pilot's chilling mayday call, (from the French phrase m’aider, meaning “help me”), before contact was lost



"Mayday...no thrust, losing power, unable to lift"



https://www.financialexpress.com/india- ... p/3878194/

[vera_k]

On a different but related note.

Aircraft crashes were previously assumed to be unsurvivable. Therefore, very little was done to promote survival when building aircraft. That changed in the last 20 years or so with improvements like stronger seats.

Are there other improvements possible? Like perhaps fire suppression systems to help in a crash like this one?

[tandav]

There is a video explanation from an American Boeing Pilot (who is still flying planes) explaining probably a human error.
Hi theory is : as the plane goes up from runway (2-3 degrees nose up and about 50 -75 feet up), the person who is flying says gears up.
And the co-pilot then leans forward and grabs a lever to activate the undercarriage to be lifted up. This makes the plane more aerodynamic as it is picking up speed and gets to about 10-12 degrees up and keep climbing.
His theory is Human Error : the Co-Pilot instead of grabbing the lever to pull under carriage up grabbed the lever to pull the flaps in. This resulted in loss of lift added with more drag from the undercarriage. The Pilot tried his best to get more lift but unsuccessful and the plane just glided down and crashed as there was no lift.
He had no time to dump fuel as well.
Now this is all speculation and theory
We have to wait for the investigation report mind you.

Not a pilot . The most reliable YouTube channel on air crash is mentor pilot . He is a veteran instructor pilot and air crash investigation expert . He does Swiss cheese analysis of all aircrashes on his channel since 1970. He has a great video on this yesterday. Requests people to not speculate . He goes over that theory . Says it's one possibility not there is no evidence that happened . Moreover the wing flap levers and the landing gear livers look and feel very different. They are designed that way because such errors have happened in the past .

https://images.app.goo.gl/w3LkP7zsxQQK25PNA

Preposterous! Look up where the landing Gear retraction levers (yellow lever in center of panel) and flaps levers (starboard of the throttle) are positioned. No sane pilot could have mistaken Flaps up to Gear up on take off

All the evidence points to catastrophic loss of thrust in both engines and deployment of the RAT and subsequent crash 1.5Km away.

Why both engines cut off at the most critical point of the takeoff flight regime is to be investigated. Sully of Hudson river fame lost both engines at ~3200 ft /860m and landed safely after using 208 seconds to land in the river. Sully maintained a sink rate of 4m/s. The AI pilots held the 787 plane to a sink rate of sub 2m/s but had no time to recover. At maximum 200m ASL they were only 120m above the actual ground (80 ASL) when thrust loss occurred. Building top is at 95 ASL. At a sink rate of 2m/s they hit the building in 24 seconds covering 1.6Km at 150 knots ground speed.

[vera_k]

Boeing 787 identical to crash jet made four emergency landings in a month

[Vayutuvan]

Preposterous! Look up where the landing Gear retraction levers (yellow lever in center of panel) and flaps levers (starboard of the throttle) are positioned. No sane pilot could have mistaken Flaps up to Gear up on take off

You answered a question I was about to ask. If they were not far apart, then many more accidents would have happened. I have friend who done a PhD in designing dials and displays in the cockpits of aircraft. Positioning of Displays and controls is done by a team of ergonomics and visualization experts. A plane which had been in service for as long as Dreamliner proved itself that the controls/levers etc. are properly placed.

[chetak]

Air India crash: Black Box including the Digital Flight Data Recorder of the Boeing 787 found from roof of hostel building hit by the plane

https://apnews.com/article/air-india-pl ... 8922cc94b7

The plane’s digital flight data recorder, or black box, was recovered from a rooftop near the crash site and India’s Aircraft Accident Investigation Bureau said that it had begun its work with “full force.”

The black box recovery marks an important step forward in the investigation, Civil Aviation Minister Ram Mohan Naidu said in a social media post.

The device will reveal information about the engine and control settings, in addition to what the voice recorder will show about the cockpit conversations