My heart goes out to the families of the passengers and crew who’s lives were lost. The airline’s employees also have my deepest sympathies. For the next year and beyond, they will question everything about an operation that 24 hours ago was a source of deep pride.
I flew the 737 for 20 years. Most of that time was in the -800, the type destroyed in the tragedy yesterday. We, mainly me, have opined to the tune of thousands of words about the Max crashes and the debacle that Boeing has become. But the airplane is a great one. What makes it great is its utter simplicity. Other airliners become lawn darts when hydraulic pressure is lost. The 737 remains perfectly controllable through cables, servos and (maybe?) anti-servos. Much of the technology that resides inside a new Max as it rolls out of the factory is unchanged from the first 737 in 1964. I write this to set up what has me so baffled by the accident. Here’s what we know at this early hour while crews are still searching for survivors:
A video I’ll not post here shows the airplane landing smoothly with none of the gear extended. It barely decelerates before exiting the right edge of the runway and immediately striking a concrete wall and exploding. All but about 10m of the tail section is practically atomized by the impact. Apparently the crew reported a bird strike before they attempted the landing. That’s all I know to this point.
Why is the gear up? There is no explaining it. There is never a reason that a pilot would not want even just one extended; the others refusing to extend. A single main gear provides much-needed braking while the other side is kept off the ground until full aileron no longer is able to do so. A nose gear without the mains (might) provide some steering capability. I do not see how it is possible to not be able to extend at least one. And I find it unlikely to the extreme to be unable to extend them all. With both hydraulic systems inoperative, the gear simply freefalls. There’s a little door on the floor of the flight deck. You open it and pull three long cables which release the uplocks. Why not land fully gear up instead of a partial extension? Because the metal belly and engine pylons provide very little friction against asphalt. Metal melts away almost viscously and the result is more like hydroplaning than breaking, at least initially. Another odd thing about the video, at least as far as I can tell after a dozen views, is that the speedbrakes do not seem to be extended. This is absolutely to very first act of the crew the instant the metal hits the pavement. Normally it’s automatic. But without wheel spinup, the handle has to be pulled. Is it possible that there was no hydraulic power to drive the speedbrakes? It’s possible if both engines were so wrecked by birdstrikes that they had nothing. (Sully’s scenario). The landing APPEARS to me to be with at least some flaps and/or slats extended. If so that would mean at least one engine was running.
But not necessarily at touchdown. It could be, in fact I hope it turns out to be, that some event (birdstrike) took out both motors early on the approach, leaving the crew insufficient time to pull the handles and no way to configure further. On glidepath, even engineless, they would have enough potential energy to continue the approach to the runway surface. With a strong enough right crosswind, at some point the cable-driven rudder would be unable to overcome the weathervane tendency of the airplane. If this is what happened, then the crew AND the Boeing did the very best they could with the hand they were dealt.
[EDIT] Responding to @Troll below. That’s wild about the KLM over-run! It is just the type of incident where full knowledge benefits us most WHILE likely being the one we will hear nothing more about. This lack of communication is the biggest barrier to the elusive goal of perfect safety. Even internally within my airline, we’re mum about incidents like the KLM one. We blame lawyers and, yes, that’s part of it. But really it comes down to the very complex business of safety investigation. So what do pilots do?
They speculate. Which is what I’ve done above. We simply have to do it. To stay mute and not process the horror of it is not the answer. Neither is throwing the crew (or the plane) under the bus. I hope I’ve done neither with what I wrote above. To reiterate @Troll’s point, and I agree completely, the above is one of dozens of scenarios and almost certainly it is wrong. But wrong in a technically informed sense if you get the distinction.
