Breaking news: Ethiopian Airlines flight has crashed on way to Nairobi

[Gabriel]

I watched them at the beginning of the video struggle with manual pitch and yoke forces. Nobody thought to retard the thrust levers.

15:30 into the video he finally mentions that, as an alternative to the 'roller coaster maneuver", you could always reduce speed.

I involuntarily shouted out "Duh!"

Why are we talking about a procedure to escape from a mistrim at these speeds that is anything other than reducing the speed?

The MCAS scenario is deleterious to situational awareness and results in tunneling concentration to the pitch control rather than the thrust/speed situation. That is the real danger it represents. If the Ethiopian crew had simply reduced thrust, especially at the Vmo alert, they would not have gotten into a mistrim situation that exceeds manual trim ability. You can't fix that. You have to REMOVE the possibility that an erroneous MCAS activation will ever happen, or at least limit the amount of mistrim it can create.

I would prefer to reduce speed by pulling up first. Put the plane 20 degrees nose up.

The reason is that the throttles are a double-edged knife. When you pull back on the throttles the AoA and pitch will tend to reduce immediately due to the effect of the (loss of) thrust on the underslung engines, forcing you to apply more back pressure to prevent that. Then as (if) speed goes down the plane will again tend to pitch further down due to the speed stability. The bottom line is that while the speed will reduce initially, the trim speed without thrust will be higher than the trim speed with thrust (due to the thrust-pitch coupling), so you will have limited time to react and turn the wheel quickly while the transient reduction of speed lasts.

If you have enough strength to briefly pull up (eve if it takes the effort of both pilots together) and establish a 20 degrees climb (or why not 25), the things will only go better from there, and you are gaining altitude at the same time than reducing speed which is another plus.

[Evan]

I would prefer to reduce speed by pulling up first. Put the plane 20 degrees nose up.

The reason is that the throttles are a double-edged knife. When you pull back on the throttles the AoA and pitch will tend to reduce immediately due to the effect of the (loss of) thrust on the underslung engines, forcing you to apply more back pressure to prevent that. Then as (if) speed goes down the plane will again tend to pitch further down due to the speed stability. The bottom line is that while the speed will reduce initially, the trim speed without thrust will be higher than the trim speed with thrust (due to the thrust-pitch coupling), so you will have limited time to react and turn the wheel quickly while the transient reduction of speed lasts.

If you have enough strength to briefly pull up (eve if it takes the effort of both pilots together) and establish a 20 degrees climb (or why not 25), the things will only go better from there, and you are gaining altitude at the same time than reducing speed which is another plus.

Well, fortunately, the instinct is to first pull up anyway. Fine. But for god's sake, if the thrust is at or near take-off setting, reduce that immediately after. It might require a higher trim speed but this is achieveable, whereas recovering from a high-speed mistrim may not be. This seems so much more sane and practical then the so called 'roller-coaster manuever'. The MCAS upset happened at around 250kts. You have plenty of time to pull up, trim up (manually), and reduce thrust before getting anywhere near an unrecoverable mistrim situation. Not a word about this until 15:30 into that video.

[elaw]

If you're talking about instinct, good luck getting pilots to reduce power when the nose is dropping. One of the most basic things that pilots are taught (and which occasionally is incorrect as we've seen here) is that power is what makes the plane fly, and if the plane wants to head toward the ground, adding power is one of the first and most important things to do.

[Evan]

If you're talking about instinct, good luck getting pilots to reduce power when the nose is dropping. One of the most basic things that pilots are taught (and which occasionally is incorrect as we've seen here) is that power is what makes the plane fly, and if the plane wants to head toward the ground, adding power is one of the first and most important things to do.

One of the first things pilots are taught is that overspeed = death. We are talking about a take-off power setting propelling the aircraft beyond Vmo (despite the speed tape and the alert). There is no issue with reducing power at that point. It wasn't done because it was overlooked. Tunnelling.
Any procedure to deal with the combination of high speed and excessive trim forces must involve reducing thrust as a memory item.

[Gabriel]

May I remind you that the plane flies very happily at about 180 knots steady with take off thrust, after take off and with the nose pointing up. Gravity is much better than drag at reducing speed, and again with the 2 pluses of gaining altitude and no pitch-down thrust coupling.

[Evan]

May I remind you that the plane flies very happily at about 180 knots steady with take off thrust, after take off and with the nose pointing up. Gravity is much better than drag at reducing speed, and again with the 2 pluses of gaining altitude and no pitch-down thrust coupling.

Why are you talking about this as if it's one thing or the other. Moderate ANU attitude & reduce thrust. Together these things reduce airspeed (or prevent it from increasing). You can ALWAYS trim manually if you keep the speed under control. The problem is excessive airspeed. The aircraft automation is pitching you down. The goal is to stabilize BOTH attitude and airspeed.
Yet no mention of reducing thrust until a brief mention at 15:30.

[flashcrash]

I guess you can't reheat an omelet without breaking a few eggs.

Boeing Q1 earnings coming up at market close tomorrow.

[3WE]

Evan:

Pitch controls airspeed.
Power controls altitude.

Don’t go all black and white on me, but I don’t think it would have slowed the 737... underslung engines and all.

I’d tell you to ride a bike, but this one requires some time in a 152.

[Evan]

Don’t go all black and white on me, but I don’t think it would have slowed the 737... underslung engines and all.

The intent is not to slow down, it is to not speed up. You forgot:

Speed-on-elevator doesn't work so well when you are fighting to keep the pitch above neutral while at 98% N1.

[Gabriel]

The intent is not to slow down, it is to not speed up. You forgot:

Speed-on-elevator doesn't work so well when you are fighting to keep the pitch above neutral while at 98% N1.

Of course it does. Why not? Please explain.

[Evan]

Of course it does. Why not? Please explain.

Well, I mean, yes, it works, if your intention is to aggressively accelerate beyond Vmo, until the aircraft becomes uncontrollable. In fact, it's perfect for that.

If your intention is to live, I would advocate some thrust reduction, some elevator and pitch trim management and some flaps as soon as possible.

If your intention is to live, your goal should be to stabilize, get below 250kts and get flaps 1 back out.

As opposed to speeding up in a roller-coaster sort of way.

[Gabriel]

Well, I mean, yes, it works, if your intention is to aggressively accelerate beyond Vmo, until the aircraft becomes uncontrollable. In fact, it's perfect for that.

If your intention is to live, I would advocate some thrust reduction, some elevator and pitch trim management and some flaps as soon as possible.

If your intention is to live, your goal should be to stabilize, get below 250kts and get flaps 1 back out.

As opposed to speeding up in a roller-coaster sort of way.

What's the problem with setting pitch to 20 to 25 degrees nose-up? I am not saying do not reduce the throttles too, but if you did just pitch gravity will take care rather quickly, you will have no thrust-induced pitch-down tendency, and you will move away from the dangerous hard surface below called Earth.

[Evan]

What's the problem with setting pitch to 20 to 25 degrees nose-up? I am not saying do not reduce the throttles too, but if you did just pitch gravity will take care rather quickly, you will have no thrust-induced pitch-down tendency, and you will move away from the dangerous hard surface below called Earth.

Ok, at this point I have to ask what we are even talking about. I thought we were talking about technique to recover from a scenario in which the trim has run amuck (in an ANU way) and the speed has reached the level at which it is very, very, very hard to use manual pitch trim. I don't see how that is going to happen with 20° of pitch. If you can manage to set (and maintain) 20° of pitch, I don't think you are having the problem we are (were) discussing.

I'm watching the man who calls himself Mentour Pilot running through a sim session in which he cannot maintain 20° of pitch, is flying beyond 350kts and never thinks to pull back on the two big fire-breathing turbo-cannons under the wings that are propelling him into an unrecoverable situation. It's not just him. The Ethiopian pilots never seemed to think of this either. As I've said 5.4 billion times already, I attribute this to tunnelling, but I'm rather astounded that nobody seems to be focused on it as a prime causative factor, and that Mentour Pilot only quickly mentions it as an option to the absurdly traumatizing 'roller coaster' maneuver that time forgot.

[Gabriel]

Ok, at this point I have to ask what we are even talking about. I thought we were talking about technique to recover from a scenario in which the trim has run amuck (in an ANU way) and the speed has reached the level at which it is very, very, very hard to use manual pitch trim. I don't see how that is going to happen with 20° of pitch. If you can manage to set (and maintain) 20° of pitch, I don't think you are having the problem we are (were) discussing.

I am talking about any point where you suggest the pilots should or could have reduced the throttles.

Do you realize that keeping 0 degrees of pitch requires the same effort than keeping 10, 20 or 30 degrees of pitch?

You do need at least a little bit of extra authority to pitch up from one to the other, but Ethiopian had that extra authority all the way to the last activation of the MCAS (see proof below), and after that point reducing the throttle would not have helped the tiniest bit in any way anyway, the only solution by then was to trim up with the thumb switch (duh!).

[3WE]

The intent is not to slow down, it is to not speed up. You forgot:

You forgot "Underslung engines"

Power back.

Less thrust/more drag from big engines located below the CG.

More nose down.

More speed.

More pressure on the bound up trim mechanism.

The ground comes up more faster.

I'm not seeing any advantage to powering back.

(This does not dismiss additional, fairly powerful phugoid-behavior tendency to largely maintain airspeed in spite of power changes- that also is working against your efforts to slow down.)