Last Wednesday an Emirates 777 crash landed in Dubai. I haven’t really been following the play-by-play on this too much (well, aside from the painful-to-watch evacuation), though up until now I haven’t really heard any reputable theories as to what happened. In this instance the pilots are alive, there are lots of eyewitnesses, and presumably it’s easy for them to recover all the recorders, so I’m surprised by the lack of information so far.
— Alex Macheras (@AlexInAir) August 3, 2016
Well, my friend Jim passed along a fascinating article from The Australian which is written by a pilot with over 45 years of flying experience, and who was a senior captain at Emirates for over 15 years. He has a pretty straightforward explanation/theory of what happened to EK521, which he says could happen to anyone. Not surprisingly, automation is to blame.
Based on what we know, the plane’s wheels touched the runway, and then the pilots attempted to perform a go around, which should be a pretty standard procedure. However, during the go around the plane fell to the runway.
In case you haven’t heard it, here’s the ATC audio from the incident:
So, what’s the pilot’s explanation of what happened? Basically when you initiate a go around, you simply push a “TOGA” switch (which stands for “Take Off, Go Around”), and then the plane automatically powers up its engines to sufficient power for the go around, while you make sure you maintain a positive rate of climb and raise the landing gear. It’s one less thing for pilots to worry about in a go around, so that they don’t manually have to push the throttles forward.
But according to this pilot, that also ended up being a problem, since the plane’s wheels had already touched the ground, which meant the “TOGA” command wasn’t activated as usual:
But in the Dubai case, because the wheels had touched the runway, the landing gear sensors told the autoflight system computers that the aircraft was landed. So when the pilot clicked TOGA, the computers — without him initially realising it — inhibited TOGA as part of their design protocols and refused to spool up the engines as the pilot commanded.
Imagine the situation. One pilot, exactly as he has been trained, clicks TOGA and concentrates momentarily on his pilot’s flying display (PFD) to raise the nose of the aircraft to the required go-around attitude — not realising his command for TOGA thrust has been ignored. The other pilot is concentrating on his PFD altimeter to confirm that the aircraft is climbing due to the aircraft momentum. Both suddenly realise the engines are still at idle, as they had been since the autothrottles retarded them at approximately 30 feet during the landing flare. There is a shock of realisation and frantic manual pushing of levers to override the autothrottle pressure.
But too late. The big engines take seconds to deliver the required thrust before and before that is achieved the aircraft sinks to the runway.
What remains to be seen with this theory is what caused the go around, especially after the plane’s wheels had already touched the ground. Not that a go around as such is unusual, but it’s certainly rarer to have one after the wheels already touched the runway. Apparently there was a sudden wind gust, which may be to blame.
I recently had the opportunity to fly a full motion Boeing simulator, and even did a go around. The process was indeed very easy — I pushed the “TOGA” button, pulled the nose up, and put the gear back up. It’s perfectly plausible to think how both pilots could have been busy and not realized that the auto-throttle hadn’t actually been activated. After all, pilots are taught to rely on their systems.
It’ll be some time before we get an official report of what happened, though this explanation from a former Emirates captain and pilot with 26,000+ flying hours sounds plausible. As pilots are increasingly taught to rely on automation, it presents a whole new set of dangers.
What do you make of this theory on EK521?