Clear skies, no LiveATC but reports of single Mayday call, gear out but no flaps and no control inputs visible in the grainy video. Something has to go really catastrophically wrong with a modern jetliner for that to happen, like the very dense flock of birds in Korea with the 737 a couple of months back.
The very short intersection takeoff seems like a good hint (and terrible practice), but all gears and engines look kinda OK from the outside. If they‘d scraped something on takeoff hard enough to take out both engines, there’d probably be some visible damage, or at least some gears sheared off.
EDIT:
Fully agree with the speculation in light of tragedy comments, but aviation is a bit of a special case. The reason it’s so safe is because an awful lot of people immediately start looking into potential reasons and then spend years getting to the bottom of it. The initial speculation is like an exercise: what could have happened? What if I’m in that situation, and need to act now, without knowing much of anything? If you do that a couple of dozen or hundred times throughout your life, it really builds a foundation for when an actual emergency ever happens to you.
It’s a bit like the reason most flight attendants in the emergency exit jump seat across from you won’t talk with you during the actual takeoff and landing: they‘re mentally walking through a potential emergency and what they‘d then need to do. Every single time. So if it ever happens, there‘s muscle memory, 10000x over.
EDIT 2: see the Flightradar24 comment below, it looks like they did backtrack and use the full runway.
That is normal and standard procedure if you're having issues lifting the plane, because retracting the gear means _increasing_ drag for a crucial 10/15 seconds as the doors open and thus slowing the plane further.
> but no flaps and no control inputs visible
Standard Dreamliner operating procedure, you take off at flaps 10 or 5, they are barely visible from the outside, see many random videos of 787s takeoffs on Youtube like this:
> That is normal and standard procedure if you're having issues lifting the plane, because retracting the gear means _increasing_ drag for a crucial 10/15 seconds as the doors open and thus slowing the plane further.
Oh fascinating! I would not have considered that but it totally makes sense.
True on both counts, was a quite early comment and initially thought they're coming back in to land vs barely having taken off. Only leaves control inputs but given how short the video is it could also be that there simply wasn't much to input/correct anymore despite the slight rocking.
Can't edit anymore, but the general gist of catastrophic failure needed to prevent a 787 from climbing out of this situation still holds.
I don't think you'd expect any control inputs in that scenario. They were level with a reasonable pitch angle. Aircraft attitude was fine, they just didn't have enough power to arrest the descent. Such a loss of power with a full load of fuel definitely indicates a swift catastrophic failure to the engines at least.
Regarding the intersection takeoff, Flightradar24 just tweeted this:
> We are continuing to process data from receiver sources individually. Additional processing confirms #AI171 departed using the full length of Runway 23 at Ahmedabad. RWY 23 is 11,499 feet long. The aircraft backtracked to the end of the runway before beginning its take off roll.
The engines power the hydraulic actuators in an aircraft an aircraft of that size cannot be trivially controlled without that hydraulic system. The APU should have been started to provide backup power in the case of engine failure but during take-off there is already very little time to do anything and it's possible that the sudden workload overloaded both the pilot and copilot or some other human factors were involved.
That being said, in the video I saw, the aircraft was already going too slow to realistically recover. And all you would get at that point is just an extended duration of glide which at best would let you find a less populated area to crash into.
You can hear what sounds a lot like the very distinct sound of the RAT having been deployed in one of the videos. There is also no main turbine sound. This really seems like dual engine failure, for whatever reason.
I saw you mentioning this but the RAT on the 787 sticks out of the bottom and should have been visible at around :04 seconds into that video when the aircraft silhouette is visible clearly against the background.
Although it's possible I am just missing from the video. You are right that the sound is quite distinct and can be clearly heard in the video.
The RAT is surprising tiny on the 787, and this is a phone video of a monitor, then run through Reddit compression. I am of course not 100% sure about any of this.
Yeah I saw that picture and came back here. I think you are 100% right that the RAT is deployed.
From the video of the runway it also seems like the aircraft didn't do a short takeoff (ADS-B location data is always crappy on the ground in my experience so this is entirely unsurprising).
There was a "smoke cloud" from behind the left engine which could also have just been a dust cloud right after rotation.
The flaps allegedly could be at only 5° (which is why they're so hard to spot) because of the runway inclination.
Air conditioning is powered by bleed air from the engines (or the APU or a ground source). The APU wouldn't be running during any normal flight, it's normally only ever used on the ground when the engines are off and there's no external power source.
So I am not sure what you are trying to say here, sorry.
I don't really know enough about this, but what would you expect the pilots to do with that control if they don't have any thrust? Unless there was a suitable landing spot very, very close I don't see what they could do even if they have full control of the plane. There is nothing they can do except getting the engines to work to avoid a crash, the only thing controls would give them is the option to choose a slightly different place to crash.
But also how long after take off do you retract the flaps? Can it be a pilot error (took off without flaps?). It happened more than once in the past, though I thought a modern plane like the dreamliner would make that mistake nearly impossible.
An intersection takeoff is a takeoff where you do not use the full length of the runway. When you are a large aeroplane with a full load, reaching the necessary takeoff speeds required to rotate (pull up and begin lifting from the ground) can take longer than normal, at which point the climb speed will also be reduced if not properly compensated for (e.g. you miscalculate something and set the wrong elevator trim/takeoff thrust/something else).
When you are taking off, you have a short portion of the runway which you can use to abort the takeoff depending on failures, but that portion can become even shorter depending on the length of the runway.
Usually the first part of takeoff you would abort for almost any reason, and the second part you would only abort in a serious emergency, once you reach a certain point you simply cannot afford to abort because you will not stop in time to crash into whatever is at the end of the runway at which point you must take-off even if you are going to immediately request an emergency landing afterwards.
So if you are heavily loaded, with a lot of people on board, and you do an intersection takeoff, you are taking a risk that if you made a mistake or something goes wrong you will not have the ability to safely recover. That's why it's a terrible practice in this case. All it does is save a little bit of time which would be spent taxiing to the actual start of the runway.
Why is it a thing? Everything else in aviation seems to have good amounts of checks, balances and buffers. It feels the same to me as skimping a couple percent on fuel or doing less frequent maintenance. Both also reduce turnaround time.
Depends on the circumstances. Probably not the case with a jet like a 787, but sometimes ATC will allow small planes to 'cut the line' with an intersection takeoff.
This runway was over 2 miles long. If you are in a smaller commuter prop plane or small jet, you don't need half that space for the takeoff. You call up ATC and they give you the option of taking off at an intersection now, or being #15 in line behind the heavies, its totally fine to do that if you are within the operating margins of the aircraft. The pilots have already done the math to know exactly how long of a runway they need for the worst case scenario (rejected takeoff just below V1), so if they know that they need 5k feet worst case scenario, and are offered an intersection takeoff with 7k feet of an 11k foot runway, there is already pretty big margin built in.
The thing to remember is that the aviation community and manufacturers have decided that once a jet is past a certain speed, you are committed to taking off and climbing out no matter what is going on. There is no circumstance where airliners will go beyond that speed and then try to reject the takeoff, and land back on that same runway.
As far as fuel, you might be distressed to know that you rarely fly with full tanks. They typically fly with the amount of fuel their route uses for the load they have + a margin for diversion. This is both a cost savings measure, as well as an operational concern (for example at Denver during a hot summer day, a lot of planes can't be loaded to maximum weight and still be able to do a rejected takeoff)
Good question. False sense of routine, experience? Definitely a pet peeve.
Was flying as a passenger on a really small airline (8 seater plane, Green Air) out of San Jose in Costa Rica. We got cleared for takeoff ahead of a United 737, at most 500 feet into the humongous runway for that plane. Yet the pilots still put in the 2 minute effort to taxi back to the beginning of the runway, even though they could have easily taken off from where we entered it. Don’t know if it was their protocol or the pilots decision, but I will trust this airline for a very long time.
Pilot here: even in my small Cessna I will backtrack do you know why? Because it gives me that money more options to work with in case something goes wrong with my take off.
If something large had just taken off ahead of you, it was probably not safe to go anyway. Wake turbulence can kill you. If you need to wait 2 minutes, why not back taxi? It'll feel like doing something vs nothing and you get the extra extra runway.
Usually some form of mis-management which in this case may have put pressure on the pilot to accept a shorter take-off option due to some minutes of time saved. Sometimes pilots also might get their priorities wrong. There's a concept of "get-there-itis" which is also a common cause of crashes but it's currently unclear if it was a factor in this case.
I imagine in a while we will all be able to read the investigation reports, since the aircraft crashed shortly after take-off the black box recorder should contain all the information we need to figure out most of what happened including possibly the reasoning for the decision to make an intersection takeoff.
Less time on runway means more throughput for a given buffer time between planes or larger buffer for a given throughput.
Now, obviously there's a discussion to be had about where the line is and what should and shouldn't be standard operating procedure but there's basically no safety improvement to have even a fully loaded 757 or Learjet or whatever drag it's butt to the very end of a 15000ft runway.
A pilot may be trying to scoot out of there ASAP because he knows based on the radio and who's where that's gonna make everyone else's jobs a little easier. An airport is run by professionals all of whom are trying to make things run smooth. It's at the complete opposite end of the spectrum from a school or Starbucks parking lot.
„Runway behind you“ is drilled into your head as one of the useless things in aviation. You always want to make sure to use the most runway available to you, exactly for cases when something happens. Hypothetical in this case: you realize something’s wrong with the plane, but you’re already too fast and close to the end of the runway to reject the takeoff because you wouldn’t be able to stop in time anymore.
Large airports with heavy traffic sometimes have operational constraints to send a plane out ahead of another from some intersection, but if the ADSB data is correct, taking off from half the available runway in a fully loaded 787 isn’t a good idea. You just give up a ton of margin for errors.
it means using less then the full length of runaway available. I'm not a pilot but i'm guessing that it's not good because it adds an unnecessary potential complication to the take off.
Clear skies, no LiveATC but reports of single Mayday call, gear out but no flaps and no control inputs visible in the grainy video. Something has to go really catastrophically wrong with a modern jetliner for that to happen, like the very dense flock of birds in Korea with the 737 a couple of months back.
The very short intersection takeoff seems like a good hint (and terrible practice), but all gears and engines look kinda OK from the outside. If they‘d scraped something on takeoff hard enough to take out both engines, there’d probably be some visible damage, or at least some gears sheared off.
EDIT:
Fully agree with the speculation in light of tragedy comments, but aviation is a bit of a special case. The reason it’s so safe is because an awful lot of people immediately start looking into potential reasons and then spend years getting to the bottom of it. The initial speculation is like an exercise: what could have happened? What if I’m in that situation, and need to act now, without knowing much of anything? If you do that a couple of dozen or hundred times throughout your life, it really builds a foundation for when an actual emergency ever happens to you.
It’s a bit like the reason most flight attendants in the emergency exit jump seat across from you won’t talk with you during the actual takeoff and landing: they‘re mentally walking through a potential emergency and what they‘d then need to do. Every single time. So if it ever happens, there‘s muscle memory, 10000x over.
EDIT 2: see the Flightradar24 comment below, it looks like they did backtrack and use the full runway.