Boeing 737 MAX 8

I can well believe that the Chinese have opted for certain repair options that weren't authorized by Boeing (and when you get into issues about repairing aircraft, there's complexity even in the US, for example, the engines on planes are rent by the airlines that own the planes) and those were the things that led to the crash. Not that the Chinese government would admit to such things, of course.

It doesn’t, but one of you needs to actually do the math to prove the point.

From the graph posted earlier, it looks like the plane goes into a steep dive that gets steeper at the end. Call it 70° to start. But the velocity doesn’t change. Since they haven’t found the black box yet, I’m guessing that’s ground speed. So with and initial ground speed of, what was it, 465? knots, a 70° angle means there’s suddenly a 437 knot downwards speed (it’s very unclear to me how the horizontal speed didn’t change for so long given the much larger drag profile of a diving plane, but maybe the air is so thin at that altitude. Or the graph is wrong). Given the sharpness of the turn, it’s entirely plausible that the pilots were unable to get to the controls. But that only lasts a few seconds. Once the pitch is complete, you have the thrust of the engines now going into downward, rather than horizontal speed. You do not stay at 437 knots downward. You are not in free fall either. Unfortunately the only way to calculate the acceleration is to know the weight and thrust, and then add gravity. The initial 437ish knots doesn’t matter to the “unable to get to the controls” hypothesis, only to how soon they hit the ground.

Video shows the final seconds prior to the crash:



Nobody on that plane had any doubt of what was about to happen.

The plane looks intact. It's not trailing smoke. It's not spinning.

Can someone please post a link to the video of the alleged plane crash?

I don't think I've seen one in this thread yet.

I hope everyone is alright.

OOOOOOOOh! God's lawn dart.

I am thinking that was deliberate.

I think Paladin has that issue covered.

Maybe there are survivors at the bottom of that crazer?

I'll ask the Mayor of Portland if he has a link.

So that's interesting. Either the tracking data got bad, or the plane was climbing briefly between nosedives. Someone tried to regain control of the plane and was stopped. Maybe a thwarted hijacking? Or a temporarily delayed suicidal pilot.

A reply to the previous tweet, translated.

That's more than a 90° angle. What the hell?

The newer data shows the plane's descent was halted and (briefly) reversed before resuming, so it's looking more like a control problem than a deliberate crash.

Maybe whatever maneuver slowed the descent led to a stall. It could be that something went wrong and the pilots, in their desperation, made things worse. That's pure speculation, of course.

Some guy had shorts

Agree with you completely. A abrupt directional change can result in pulling multiple Gs even in a tame 737 without ripping the wings off.

As for the vertical descent, there is also air friction. Eventually the plane reaches terminal velocity even with thrust from the engines, acceleration might approach 32ft/sec^2 for freefall with the engines thrusting for a while, but no, they aren't going to be plastered against the bulkhead.

At 450mph though, a fall from 30K ft takes about 45 seconds.

Tuck's theory requires criminally inattentive pilots, both leaving the flightdeck, or at least their seats at the same time. Airport '79 makes more sense.

Haven't read the news today, but with no reports of radio distress calls, it's either a major explosion (video appears to show an intact aircraft) or a suicidal pilot that murdered 130 people including the other pilot.

I agree. It was likely the guy with the shorts.

wait and see, monkey boy.

I wouldn't get too hung up on that quite yet. Who is to say that the camera was perfectly level? If the camera was slightly rotated around the optical axis, that would make the plane's angle seem off.

A lot of former NTSB investigators are being quoted in the media as saying the flight recorder ("black box") is likely toast due to the severity of the crash.

So, we may never know what really happened.

You know it's a bad crash when the black box doesn't survive it.

Bad choice of words on my part. Let me rephrase:

We know what happened; we don't know why it happened.

With up to 216-242kN of thrust behind it, the chances of the plane hitting terminal velocity in a vertical orientation before hitting the ground approach 0. If it was horizontal, sure, but it came in like a missile. Anyway, they appear to have pulled up before diving again so they weren’t pinned, but it doesn’t seem impossible they could have been in other circumstances.

I was gonna suggest O2 system failure, but if there was maneuvering during the dive, never mind.

Does terminal velocity apply during a powered dive?

Terminal velocity is the speed an object attains in free-fall when air resistance becomes large enough to prevent further acceleration. Different objects (a skydiver with a deployed parachute, an anvil) can have different terminal velocities if they have different amounts of drag.

This plane hit the ground at a much higher speed than it would've in any kind of free-fall.

That the plane didn't maintain a straight track once the descent began and that it momentarily climbed out of the dive suggests that it was a control failure. If this was a deliberate action (which I now doubt), there would have to have been a struggle for the controls to explain the pitching up that occurred near the end.

It seems reminiscent of the MD-83 jackscrew failures from twenty years ago.

Yes. Acceleration is acceleration, drag is drag, doesn't matter whether the former is from gravity or an engine. Considerably harder to *reach* the now-much-higher terminal velocity before hitting the ground, but certainly theoretically possible (though perhaps not for a 737-800 on Earth - maybe on Titan or definitely on a gas giant though (if one had sufficient oxygen) - would need to do more math than I care to right now to figure it out).

When I was in Seventh Grade, my class took a trip to Put-In-Bay island in Lake Erie. It was a really neat trip because on the way over to the island we got to fly on small planes, rather than taking the ferry. So, there I am in the rear seat of the plane, with one of my friends sitting in the co-pilot seat, and I ask him how high we are. He looks at the altimeter and then turns around to tell me. As he does so, his foot bumps the control stick and the plane dives down, the pilot grabs the stick and pulls back, then wags his finger at my friend, telling him, "Don't do that again."

Dude didn't intend to bump anything, but he did, and if it weren't for the fact that we were in a slow-flying prop plane, then things might have turned out pretty bad for us. I don't remember how high we were, or how fast we were going, but it was certainly nothing like what a modern jet aircraft could travel. And when you watch the video of the Chinese plane going down, you can't help but notice that it's about 90 degrees to the ground. If you're not strapped in at the controls, how the fuck are you going to get to them and pull back on the stick to get out of the death dive before you hit the ground?

So clearly there's no possible way they weren't strapped in.

You have far more knowledge of aircraft and this situation than I do to make such a claim. All I know is that the video of the plane shows it going straight down and that it's not terribly hard for things to unintentionally go sideways which can have bad results.

To me, it seems like the possibilities for what caused the crash can fall into four categories:
1.) Some kind of mechanical/software problem.
2.) Deliberate destruction of the plane by someone onboard (possibly a member of the flight crew, but actions by a passenger can't be ruled out).
3.) Pilot/crew error.
4.) Some combination of the above.

Without recovery of the black boxes, we might never know. Maybe it's a Flight 93 type situation where hijackers crashed the plane rather than letting the passengers regain control of it, maybe it's a situation like Air France Flight 447 where something went wrong and the flight crew was too rusty to be able to handle it, or some other possibility.