Footage of the crash circulating in the aftermath may suggest an issue with the plane’s flaps. Ahmed Busnaina, a university distinguished professor, says the engine might have been the problem.
More than 260 people were killed when an Air India flight crashed shortly after takeoff in the western Indian city of Ahmedabad on Thursday. One of the 242 people aboard the plane survived the crash, which also killed dozens on the ground, according to reports.
Footage of the crash circulating in the aftermath suggests a potential issue with the plane’s flaps — a device designed to create lift.
Determining the potential causes of such a disaster no doubt requires a lengthy investigation. But for Ahmed Busnaina, university distinguished professor and the William Lincoln Smith chair, who studied the design of jet engines, engine failure is — at first glance — among the leading culprits.
We spoke to Busnaina about what could have caused the London-bound Boeing 787 Dreamliner to crash just seconds after takeoff. His comments have been condensed and edited for clarity.
There may have been some issue with the flaps. If you fly as often as I do, you know the pilots always extend the flaps down, which increases the area of the wing and the curvature of the wing. The lift is a function of wing area, and the speed of the air over the wing. That also lets you take off at a lower air speed.
I understand the gears were down, too. Usually, the gears are retracted at a certain point — at 1,000 feet, or a little higher; but it’s not especially strange that the gears are down because they just took off. So, that’s not an issue. But if they took off with the flaps retracted, for example — that would be very, very strange. It’s almost never the case.
It could be a combination of things — and it usually is. It could have been an engine stall, or a compressor stall. Typically with a compressor stall, you’ll have a loud bang or a fire in the engine. When the authorities review the black box, that will be something they can determine.
Somebody may not have set the engine thrust at the proper thrust. You don’t have to have maximum thrust, but you have to have some thrust sufficient to get you through the takeoff speed. Maximum thrust is usually required when you have a short runway. But, again, if the flaps were not used, that would make it worse, because that means you need much higher thrust on takeoff.
It could have been engine failure, corrosion, a blade breaking, for example — that would cause the plane to lose thrust right away. There are many reasons for an engine failure, all of them mechanical. Overheating, oil leaks, not enough fuel going to the engines, for example. Bird strikes are very possible. It could be a variety of things. It could also be a throttle system failure. Many of these new airplanes have an automatic throttle; so there could have been some kind of malfunction there.
It could be human error in that the pilot may not have set the flaps down, or it could be a problem with the hydraulics. In the 1970s, for example, everything — the flaps, the gears — was hydraulic. Now, that’s not the case. We have hydraulics, but it’s fly-by-wire. That means that there is a motor extending the flaps. In that sense, it could have been a mechanical failure. But, the flight crew would have known they had a problem before they took off, as you typically extend the flaps on the ground before you take off.
It signifies an emergency and very likely points to the engine; that the pilot wasn’t getting enough thrust. If there were pressurization issues, they’d have to be a lot higher than they were. Most likely it is the engine because takeoff is when you need the engine the most. Let’s say you’re at 10,000 feet or 20,000 and one of the engines breaks down. It’s no problem: you can fly on one engine. You cannot take off with one engine: you need both.
The crash was certainly a result of the plane not having enough lift and stalling. So, the question is, what stalled it? In my view, engine failure is the number one possibility. The other possibility is improper handling of the engine: let’s say somebody cut the thrust off, and it was too late to fix it. But it’s not obvious what happened here, just based on the video. There’s still a lot to learn here.