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Comment by roxgib | Hacker News Reader

It's weird to me that the pilots didn't notice that the engine thrust hadn't increased. I realise they have a lot to monitor and it all happened quite quickly, but it seems like not having your engines at 100% when they're supposed to be would stand out. I'd be interested to see what they would have seen and how obvious it was.

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The engines don’t immediately go to 100% - it takes time for them to spin up, 5+ seconds sometimes.

The engines are also very far from the cockpit, and behind them. They hear them, but not well.

So it’s not that surprising they didn’t immediately notice the problem.

That they did notice, and relatively quickly, is a sign of how well they did. But seconds matter in this scenario, and by then the lag to spin up resulted in no significant change of thrust before impact.

There is a feedback mechanism to engine throttle that is immediate and physically obvious: The thrust levers. They will move to indicate the amount of thrust the engines are ordered to produce, even when under autothrottle control.

If a pilot doesn't pay attention to where his thrust levers are when appropriate thrust is critical to safe flight, that is pilot error.

A go-around isn't complicated enough to merit reliance on automation anyway: Max thrust (or whatever is appropriate), pitch up and climb according to ATC orders or go-around procedure at airport, landing gears up, and come back for another landing attempt.

There is a button they use on go around that turns on auto throttle up, which they hit. In the scenario they thought they were in, they don’t directly interact with the throttle levers. They were paying attention to other things, like they were supposed to.

In this scenario, the auto throttle doesn’t auto throttle up because unexpectedly, they were partially wheels down for a moment, and that disables auto throttle up.

Oops.

In the "Children of the Magenta Line" video they tell you to hold the throttles physically in place in similar situations, but not this one exactly. They want you to hold all the controls when turning on or off autopilot, changing modes, or if you think something is going wrong (this kind of plane has multiple autopilots, so weird stuff can and has happened). I guess what you could do in this case is touch the throttles to make sure they are doing what you want, and retain the ability to grab them and push them forward if the auto-throttle system is not doing it.

However the levers do physically move forward and the EPR indication should spool up when the TO/GA button is pressed. Many moons ago, one of my instrument instructors was insistent on physical verification of control status even in light(er) aircraft. You didn’t take your hand off the gear lever until you saw 3 green. On takeoff or go-around, especially go-around, you kept one hand on the throttle levers until after positive rate of climb was achieved. Had the PF here had that practice, the accident would not have occurred. That said, if the TO/GA button is unavailable in a given flight mode, a more obvious verbal annunciation of that mode should be made by the aircraft.

Nod, and they changed their training to make many of those changes after this accident - one of about 40 changes.

Definitely one of those ‘if the PIC had been a little more paranoid, and a bunch of other rare/weird things had not happened, it would have been fine’ type accidents. The first officer was supposed to also verify things, but the specific step wasn’t in the training either, and wasn’t normally applicable because of the TO/GA automation.

Luckily no loss of life from the crash directly. If the firefighters had listened to prior crash issues and fixed them in their own response, likely no firefighters would have died either.

> On takeoff or go-around, especially go-around, you kept one hand on the throttle levers until after positive rate of climb was achieved.

On multi-engine jets, common training is to remove your hand from the throttle at V1 (takeoff decision speed). Most problems after that speed are to be taken airborne and dealt with there.

Moving to high thrust is felt by the gravity vector shifting off your butt a little toward your back. There's another thing that has this effect: pitching up. The two can be really hard to distinguish.

(In fact, this idea of gravity-relative-to-butt is very strong in people and when that fails to be a useful model is often when we see accidents happen.)

Diving straight down, can feel like driving forwards, which is why the https://en.wikipedia.org/wiki/Primary_flight_display is absolutely vital. One can not trust your senses when flying a plane.

On the same theme, inverted flight feels like a rapid change of pitch downwards (both accelerate you kind of toward your head), so the natural response is to "pitch back up" and get the acceleration back under your butt (which of course inverted means you actually start diving for the ground).

Not sure about that, if there is no additional thrust the aircraft will be decelerating because it's running "uphill", pulling the gravity vector forward. It'll be balanced, so you don't "feel" acceleration or deceleration.

It's the same in a car, if you are coasting in neutral and encounter a hill, even though the car will be slowing down there is no "perceptible" longitudinal acceleration because it's caused by gravity (equally acting on the car and the occupant), just like in space or one of those zero-G flights.

There would be an increase in drag when pitching up, that would also cause deceleration.

And that's why full-motion flight simulators "work".

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