Comment by chzblck
Comment by chzblck 11 hours ago
Sorry for ignorance but why is the right thing to continue to take off with an engine on fire?
Comment by chzblck 11 hours ago
Sorry for ignorance but why is the right thing to continue to take off with an engine on fire?
Being untrained but spending a little bit of time in a full motion 737 simulator that’s used to train and certify commercial pilots, I was amazed at how quickly things happen even in a scenario with no faults.
This situation (single engine failure at V1) is something that commercial pilots are certified in at every recurrent certification since it’s one of the most difficult you can be in. The crew now need to climb and go around for a landing on one engine while simultaneously running through the engine failure (and also likely fire) checklist. I don’t know if a double engine failure at V1 on a fully loaded 3 engine aircraft is technically survivable or if it’s something that’s trained on. They were put in an incredibly difficult situation just based on what reports we’ve already seen.
I would be astounded if there was anything the pilots could have done to prevent this.
The plane was two engines out and a main fuel tank on fire, fully laden with a full fuel load. No amount of training or improvisation was going to fix that.
If anything it's lucky/professional they crashed into an industrial park and didn't have time for a go around. It would have been an even bigger disaster if they'd crashed into the town centre or a residential area.
V1 is the speed at which you can still stop the plane before the end of the runway. (It is computed for each takeoff based on runway length, aircraft mass, takeoff engine power setting, flaps, wind, runway condition, etc.)
When the plane reaches V1, pilots take the hand off the throttle: they're committed to takeoff, even if an engine fails. It is better to take off and fix the problem or land again, than to smash into whatever is beyond the end of the runway.
Isn't there any margin? Does it calculate stopping before end of runway or before causing damage?
Surely uncertainty about the situation contributes to defaulting to committing, but what if it's a passenger plane and at V1 pilots know they've lost power? Wouldn't veering into highway at 30 mph be weighted against certain, big loss of life?
Edit: I now see that this has been partially answered by uncle comment
There is some margin in the calculations. But the training is very very clear, before V1 you must abort and after V1 you must continue. No discussion, no decision to make. You call V1, hands go off the throttles and no matter what you're going to fly.
The margin is for example that the plane must not just be able to fly, but also reach a minimum climb gradient to clear obstacles with a bit of safety margin. There is also an allowance for the time it takes from calling abort to actually hitting the brakes. And for example headwind is part of the calculation (it makes the takeoff distance shorter) but only 50% of the headwind is used in the calculations.
But all of those margins are not for the crew to use, the crew must just execute the procedure exactly as trained which means at V1 you're committed to continue the takeoff. And before V1 in case of an engine failure you have to hit the brakes to make sure you can stop before the end of the runway.
V1 is the decision speed with respect to a single engine failure in a multi-engine aircraft. It's the speed below rotation speed at which the decision to abort safely can no longer be made.
Captains can make the decision to abort the takeoff in the case of absolute power loss or for 'failure to fly' (where the aircraft is clearly not going to fly, e.g. the elevator/pitch controls aren't responding). But the training is adamant: if you're uncertain what has happened after V1 you try to fly the plane away from the runway.
After you reach V1, you take off.
Between V1, Rotate and V2, there’s like a 2-3kts difference (between each of them).
I am not familiar what the procedure is if you have dual-engine failure at or above V1.
To avoid mass casualties at the end of the runway - on the road, or the buildings that the runway points to. Check the layout on google maps.
More specifically, V1 is the max speed at which you're about to take off, but you can still abort from. They hit that max speed and realized there was a major problem that hypothetically, they could have slowed down from, but realistically was not possible. They had no choice.
It depends on whether or not, at the point in which you realize you have an engine on fire, you have room on the runway left to stop.
As I understand it, there is a low speed regime, under 80 knots, where are you stop for basically anything.
Then there is a high speed regime, where you only stop for serious issues, because you now have so much kinetic energy that stopping the plane, while still possible, will involve risk. (i.e. fire from overheated brakes.)
At a certain point, called V1, there’s no longer enough room to stop, no matter what your problem is. You’re either getting airborne or you’re crashing into whatever is ant the end of the runway. In general, getting airborne is the safer option, while obviously still not risk free.
However, this calculation also assumes that the engine fails in an isolated fashion, and its failure did not affect the other engines. If the failure of the left engine threw off debris that damaged the middle engine then we are now talking about a double engine failure. I’m sure the pilots knew there was a problem with the engine when they made the decision to continue, but it’s possible that problems with the middle engine weren’t apparent yet and that it only started to fail once they were committed.
Obviously, this is just speculation, and we will have to wait for the preliminary report at least.
RIP