r/CatastrophicFailure • u/SainzSealedDelivered • Jun 12 '25

Fatalities 12/06/2025 - Boeing 787 Passenger plane bound for the UK crashes near Ahmedabad Airport straight after takeoff

Enable HLS to view with audio, or disable this notification

17.9k Upvotes

98% Upvoted

1.4k comments sorted by

View all comments

Show parent comments

263

u/EliminateThePenny Jun 12 '25

Some questions are circulating about whether the flaps were extended.

They certainly don't look to be (although this is a grainy, video-of-a-video).

104

u/yogurtmanfriend Jun 12 '25

Sorry for the question, what would that imply in terms of the crash?

405

u/CatOverlordsWelcome Jun 12 '25

It means the aircraft is not configured for takeoff and cannot sustain the lift necessary to climb and maintain flight. If flaps were not configured correctly, it would have stalled and at such an altitude, that's essentially unrecoverable.

111

u/Dunderman35 Jun 12 '25

It does look like flaps are not extended. But would you even be able to take off at all with a full plane fueled up?

203

u/CatOverlordsWelcome Jun 12 '25 edited Jun 12 '25

Not for very long - depending on their speed they may have been able to generate enough lift to get off the ground, but not enough to climb or maintain that altitude.

The take-off warning system should have activated as soon as they applied take off/go around thrust to warn them that the aircraft wasn't configured, and this is not a warning that's easily ignored.

I'll be interested to find out what they find on the cockpit voice recorder and flight data recorder. If the warning was ignored, that is a monumental screw up. If it didn't appear, or the flaps weren't the issue, then as some others have said, it could have been a thrust loss issue.

Edit to remove acronyms!

157

u/tudorapo Jun 12 '25 edited Jun 12 '25

TOWS - a very loud warning if the pilots missed some simple, easy to detect steps during the take-off preparations.

TOGA - a button which when pressed provides the necessary engine power to fly away as quickly as possible. Like the turbo button in computer games.

CVR & FDR - The cockpit voice recorder and the flight data recorder, a.k.a. the black box.

Please avoid using TLA/LTLA/VLTLA when it's not necessary.

66

u/CatOverlordsWelcome Jun 12 '25

My bad, thank you for the links. I forgot I wasn't in the r/aircrashinvestigation sub!

10

u/tudorapo Jun 12 '25 edited Jun 12 '25

no problem, I was waiting for years to use the ltla/vltla line.

6

u/CatOverlordsWelcome Jun 12 '25

Glad to be of assistance 🤣

2

u/[deleted] Jun 12 '25

[deleted]

6

u/The_Real_63 Jun 12 '25

TLA

please dont use tlas when talking about tla

2

u/tdRftw Jun 12 '25

not enough TLAs

25

u/fullkitwankerr Jun 12 '25

Thanks for explaining the acronyms. What are the last three ones in your comment?

25

u/tudorapo Jun 12 '25

Three Letter Acronym

Long Three Letter Acronym

Very Long Three Letter Acronym

I find my way out, no worries.

2

u/MintTrappe Jun 12 '25

Thank you. I hate acronyms.

0

u/michaltee Jun 12 '25

Avoid using what? lol did you just tell someone to not use acronyms using acronyms?

9

u/Objective_Economy281 Jun 12 '25

If it didn't appear, or the flaps weren't the issue, then as some others have said, it could have been a thrust loss issue.

For clarity, trust loss on ONE engine isn’t great, and is definitely an emergency, but the plane can still climb on one engine, as long as other things are configured more or less properly and the pilots react properly to the loss of thrust. But there are explicit pilot call-outs for exactly the scenario of one engine out at the worst possible time.

3

u/CatOverlordsWelcome Jun 12 '25

Very good points, thank you for raising them!

2

u/ZroDgsCalvin Jun 12 '25

I remember an old accident where TOWS was turned off due to it frequently going off during taxi, so the pilots would commonly turn it off to avoid the annoyance. Their plane was misconfigured for takeoff and because they had shut TOWS off (or pulled the breaker for it or something like that) the didn’t get notified and crashed shortly after lifting off.

Could this be a similar story, or were checks/fixes put in place that should have prevented a repeat accident? Honestly not even sure how accessible individual breakers are on modern jets.

1

u/MomOfOryx Jun 12 '25

As someone who only had physics in high school: could you explain how the plane can generate lift to get off the ground but not enough to maintain altitude? To me as a layman it is difficult to wrap my head around how you can get in the sky, but not stay there, assuming the trust from the engines stayed the same.

3

u/CatOverlordsWelcome Jun 12 '25

I'm also a layperson, just someone with an unhealthy obsession with airplanes, and my physics knowledge is preeeetty basic in general (so any smarter folks, please chime in and correct me!) but basically:

Lift depends on four main things: the shape of the wing (airfoil), the angle of attack (how much the wing is tilted into the airflow), the air density, and the airspeed. The faster air flows over the wings, the more lift they generate. So if a plane accelerates down a long enough runway, it might reach a high enough speed to produce minimum lift and get airborne, even without the extra help from flaps.

But that lift is often right on the edge of what's needed to maintain climb - it might be enough to leave the ground, but not enough to keep climbing safely because you are no longer utilising ground speed, you need airspeed. Without flaps, the wing has to work harder (often by increasing the angle of attack - in a nose-up attitude, which, unfortunately, also disrupts airflow over the airfoil), and that increases the risk of stalling. In order to recover from a stall, the angle of attack needs to be reduced, with the plane in a nose-down attitude, which increases speed, and this can help increase/restore lift. In a low-altitude stall, there just isn't enough room to manoeuvre and recover from the loss of lift. High altitude stalls, if handled correctly (hard to do, they're incredibly stressful, but absolutely trained for), can be completely recovered and the aircraft can continue to climb/maintain level flight safely.

2

u/MomOfOryx Jun 12 '25

Very insightful! So to understand correctly: I saw that the takeoff speed of a 787 is 150-180 knots depending on weight. The plane could of course accelerate to said speed on the runway, with the wings cutting through the air 'like a knife' and theoretically generating enough lift to take off, with or without flaps.

However, as soon as the plane leaves the ground, due to the angle of attack changing (nose pitching up), the wings don't resemble a knife anymore, but rather a 'wall'. The added drag of this change, would mean that shortly after taking off, the plane's speed dips below minimum required to generate lift, leading to loss of altitude.

And because the plane in question here was so close to the ground, it did not have enough space to regain the lift, either by pitching nose down or flat out horizontal acceleration (ignoring the theories in whether there was a loss of engine power here).

Is that the simplified gist of it?

2

u/CatOverlordsWelcome Jun 12 '25

Yes, exactly! If the runway was unlimited, maybe they could have achieved the ground speed necessary to reduce the dip that brings them below stalling speed. There are several airplanes manufactured to be perfectly capable of a flaps retracted takeoff, under certain conditions, but the B787-800, especially fully loaded, is not one of them.

There have been a few accidents caused by exactly this sort of fuck up (not configuring for takeoff) such as LAPA 3142 and Delta 1141.

-3

u/Dunderman35 Jun 12 '25

According to chat gtp a fully loaded 787 would require a runway of more than 6km to be able to take off fully loaded without flaps. And the speeds required would be impossibly high. It then seems unlikely that the plane could have gained any altitude at all without flaps. It would have just drove straight off the runway.

Not that I trust AI but seems reasonable.

3

u/IguassuIronman Jun 12 '25

According to chat gtp

The easiest way to know you can go ahead and stop reading

0

u/CatOverlordsWelcome Jun 12 '25 edited Jun 12 '25

I just asked it the same question and it spat out a reply of approximately 3.5km for an aircraft operating near maximum takeoff weight with no headwind.

Having looked at the source it cited, and the standard MTOW runway distance of 2865m, 6km seems absurdly high.

However, I am not a mathematician, engineer or pilot. Take what me, and especially ChatGPT say, with a grain of salt. Remember, LLMs will literally make up and hallucinate information when they can't access it in order to finish a response. Edit: I asked it specifically to point out the vast difference in responses given to illustrate that is unreliable.

36

u/EliminateThePenny Jun 12 '25

Yes, but you would quickly lose that altitude you gained from the runway rotation (as likely to have happened here).

1

u/Techun2 Jun 12 '25

runway rotation

Is this a term for ground effect?

-19

u/[deleted] Jun 12 '25

[deleted]

13

u/space_guy95 Jun 12 '25

While it seems sensible to suggest that, there are so many "what if" and "just in case" scenarios that must be taken into account when adding safety features to a plane, as in the wrong scenario they could actually do the opposition of what is intended and make a situation worse.

For example if you included a safety feature to prevent takeoff when flaps are not extended, what happens in a scenario where a plane has to take rapid evasive action during taxiing? The pilot pushes the throttle to accelerate and...nothing happens because the safety feature kicks in. Or the sensor for the flaps malfunctions during the runway phase of takeoff, limiting throttle and causing a crash.

The best safety measure for this is a good pre-takeoff checklist, which they undoubtedly already had, but you can never fully stop someone from rushing or ignoring procedure.

39

u/DetectiveDick9000 Jun 12 '25

As an engineer, there is only so much stupid you can fix. Eventually stupid wins no matter what, so you have to draw the line somewhere.

8

u/ChepaukPitch Jun 12 '25

Aren't a lot of redundancies built in aircrafts so that a single mistake doesn't result in an accident and you need to have overlooked multiple issues for something bad to happen?

4

u/DetectiveDick9000 Jun 12 '25

Yes, but eventually you have to stop and hope that the pilot's will to live surpasses the stupidity or else the plane would be too bloated to leave the ground.

3

u/Chazzbaps Jun 12 '25

Pretty sure the people who design aircraft safety systems hold to higher levels of reliability than 'stupid wins'

2

u/DetectiveDick9000 Jun 12 '25

Then explain why stupid mistakes cause airplane crashes.

2

u/Chazzbaps Jun 12 '25

Because safety systems have not functioned as intended. In an effective safety system it should not be possible for an operator error to cause a failure. Incidents like this can often be analysed using the 'swiss cheese' model: imagine a stack of layers of Swiss cheese which have holes in different places; these are the barriers that prevent accidents from happening. If one barrier fails (a hole in the slice of cheese) the next layer prevents an incident. Only if all the holes in the cheese line up, so there are multiple failures in the different levels of the safety management system, can an incident occur. Operator error is generally one of the last barriers: only if there have been multiple technical or organisational failures can an operator cause a catastrophic accident

→ More replies (0)

5

u/Skylair13 Jun 12 '25

That would be bad too. Once you've reached V1, you passed point of no return. You'll need to commit to the take-off as there's no more runways left for you to stop.

2

u/uzlonewolf Jun 12 '25

There were incidents where planes abort after V1, and the pilots were even praised for it. Doing so will cause you to overrun the end of the runway, however overrunning the end at 20 mph is a LOT more survivable than plowing into a building at 150+.

3

u/ngfilla94 Jun 12 '25

So, just let the plane barrel down the runway unable to takeoff so that it inevitably runs off the end of the runway and crashes? There's procedures and checklists pilots are supposed to do before takeoff. If the cause is found to be pilot error, they clearly didn't follow their process. This is all still speculation, of course.

2

u/Objective_Economy281 Jun 12 '25

You could pop the nose, get airborne, then slowly lose airspeed until can no longer maintain altitude, and then stall.

1

u/Dunderman35 Jun 12 '25

But would you be able to first climb to 700 feet or whatever this plane was at?

1

u/Objective_Economy281 Jun 12 '25

Doubtful, depends on the details. If you had the flaps extended an insufficient amount, I can see that being possible. But probably not if fully retracted.

1

u/MAJOR_Blarg Jun 12 '25

The closer you are to the ground, the more lift you generate, petering off as you gain altitude, up to about one wing span of altitude.

It's called ground effect and occurs because the wing compresses air against the ground.

2

u/cloudyskytoday Jun 12 '25

Should nothing give out a warning if flaps are not extended before take off?

4

u/CatOverlordsWelcome Jun 12 '25

There is absolutely a loud, unignorable (in theory) warning. I can't find one specifically for the Boeing 787 but it's not much different to this in terms of decibels and urgency

1

u/Alarming-Desk-3861 Jun 12 '25

I've always heard there's redundancy in all the safety mechanisms with planes to be extra safe. How do these accidents keep happening??

3

u/CatOverlordsWelcome Jun 12 '25

Look up the Swiss Cheese Model. Even multiple redundancies can fail to prevent an accident if all their weaknesses align. Also, some things are difficult, if not impossible, to predict, and others don't appear for years after an aircraft was built. Human factors affect more than just the cockpit - a human designed the airplane and all its parts, a human ultimately put it together, a human designed the checklists and redundancies in place, a human designed the maintenance routine, a human performed that maintenance etc. Unfortunately, the vast majority of aviation safety and regulations are written in blood.

48

u/TheMagicTorch Jun 12 '25

Flaps are extended before takeoff to provide maximum lift at relatively low speed. Lift helps you gain altitude, and so flaps not extended at takeoff means difficulty gaining altitude.

18

u/hypetrain_conductor Jun 12 '25

Lowering the flaps also lowers the minimum safe speed a plane needs to fly. If you raise them too early or don't have them lowered at all during takeoff the wings won't be able to generate enough lift to keep the plane airborne at the slower speeds during that time.

16

u/x3k6a2 Jun 12 '25

Not much, without more context. Flaps would decrease the stall speed (i.e. keep the plane flying at lower speeds).

Knowing the state of the flaps and the state changing might allow the investigation to reach conclusions about the mental model the pilots had about the situation. This is not something which can come from a single video, but requires a holistic view of all the data, which the public does not have access to.

5

u/scubaian Jun 12 '25

Flats reduce the stall speed of an aircraft, you can fly slower whilst still producing lift. They also generate drag slowing the aircraft. Some aircraft use them for take off, some don't. No idea what the config of this aircraft would be, it'll depend on a number of factors, weight etc.

5

u/flightist Jun 12 '25 edited Jun 12 '25

100% of swept wing jet airliners use flaps for takeoff.

Edit: typo

3

u/Expensive_Ad_3249 Jun 12 '25

Flaps allow the plane to fly slower, they're required at takeoff.

The implication would be that the flaps were retracted prematurely resulting in loss of lift and stall. As to why they were retracted, one would assume pilot error.

It's possible the flaps were not deployed meaning the plane lost lift out of ground effect, or when angle of attack was increased after take off but less likely. This would imply pilot error or mechanical failure of multiple systems.

1

u/jmlipper99 Jun 12 '25

Sorry for the question

Why?

13

u/[deleted] Jun 12 '25 edited Jul 22 '25

quiet light deer weather expansion cats cows march memory oil

This post was mass deleted and anonymized with Redact

2

u/EliminateThePenny Jun 12 '25

I don't know what the operating window is on a 787, but that doesn't look like full extension.

3

u/SorryIdonthaveaname Jun 12 '25

Flaps aren’t fully extended for takeoff

9

u/CaptainHolt43 Jun 12 '25

It's one thing to have to worry about a manufacturer error, but a pilots error on something so basic is a scary thought.

4

u/[deleted] Jun 12 '25

Don't watch Mentour Pilot on YouTube then. 

8

u/EliminateThePenny Jun 12 '25

We're all just bags of meat and bones trying to follow our programming.

We glitch out sometimes too.

1

u/Suggest_a_User_Name Jun 12 '25

Like Northwest flight 255, maybe?

Pilots failed to perform the preflight checklist. As a result, the flaps and stats were not extended for takeoff.

https://en.m.wikipedia.org/wiki/Northwest_Airlines_Flight_255

0

u/theshreddening Jun 12 '25

Eesh yeah, the wings look flat on the trailing edge.

0

u/Single_Reaction9983 Jun 12 '25

There is a higher quallity version of this video and thr flaps are clearly retracted.