Comment by eh_why_not
13 hours ago
So many mistakes. A notable part is this:
>> CVR: 00:15 A pilot called for a go-around.
>> FDR: 00:15 Brakes were released at a groundspeed of 120 knots and throttles were increased to a value consistent with go-around thrust.
>> FDR: 00:11 The throttles were reduced to idle power and the brakes were re-applied. The groundspeed was 117 knots. The throttles remained at idle, and brakes remained applied until the end of the recording.
So they decided to go-around (i.e. do not land and climb immediately, going full thrust), then 4 seconds later changed their mind and went back to power idle and brakes (unclear how speed didn't increase).
While they were still late in calling a go-around (they should have done it before being anywhere close to touching down due to their unstable approach), guessing those 4 seconds contributed to the disaster by a lot.
> unclear how speed didn't increase
How can you comment as if you are knowledgeable enough about aviation to speak on this with authority, but you aren't aware that turbofan engines don't have instant throttle response and need time (up to 8 seconds) to spool up? I think a little more restraint is warranted in something like this if you don't know something that basic.
You can actually do the math to work backwards and approximate how much thrust the engines were producing during that time, which was about 15,000 lbf (vs ~120,000 lbf max thrust for a 767-300er) which reduced how quickly they were decelerating by... Maybe a few % or so. But they didn't start accelerating yet. They would have in another second or two, however.
I'll agree that they should have gone around far earlier; getting non-spurious GPWS callouts on final because you're trying to dive and find the glideslope is... Crazy, and configuring landing flaps over the numbers is also crazy, and so is landing 10-20kts faster than the highest possible Vref value for the type, and everything else. But that's fairly obvious...
> How can you comment as if you are knowledgeable enough about aviation to speak on this with authority, but you aren't aware that ...
This is par for the course for HN; smart people applying first-principle thinking on unfamiliar domains for about a minute, which confirms the biases of other outsiders who vote the plausible, but not-quite-right comments to the top.
This is par for the course for HN; smart people failing to interpret a comment in a charitable light, preferring instead to author a condescending reply in an apparent effort to score imaginary points at the expense of intellectually stimulating conversation.
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This sounds about right to me, so I upvoted.
Lots of armchair experts incorrecting each other
HN is particularly notorious for armchair aviation experts. I am an aerospace engineer having worked in airworthiness & certification as well as maintenance/repair/overhaul on multiple different aircraft types both fixed and rotary. I mention this only to establish my bona fides as someone who knows their shit:
The comments here during the 737 MAX MCAS thing were fucking wild. So many randoms spitting out confidently incorrect nonsense.
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HN = A bunch of weirdly aggressive nerds who fail to explore nuance living in the same prison cell.
We're not jurors or NTSB investigators - this is just a public messageboard on a tech-focused platform. It's totally fine to speculate and wonder here ... and to be corrected respectfully.
Not having handles where they should be at 1000 callout should have been an instant toga party.
That they passed their minimums and still weren't set up correctly is shocking, yes. How can you commit to landing instead of going around when you're not configured for landing?
The more egregious thing to me though is ignoring the GPWS callouts on approach because they were chasing the glideslope. If you can't maintain a stable approach, you need to go around, it's the first thing you learn.
You expect this behaviour from a first-timer in the sim, not a commercial cargo pilot.
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> How can you comment as if you are knowledgeable enough about aviation to speak on this with authority, but you aren't aware that turbofan engines don't have instant throttle response and need time (up to 8 seconds) to spool up? I think a little more restraint is warranted in something like this if you don't know something that basic.
I'm a pilot, and I don't fly turbofans/jets. Not claiming any "authority", but qualified to comment... It's not "something that basic" unless you fly in that category, there's a lot more to aviation experience than knowing a fact about an engine you don't use. (But hey, congrats to you that you know it!)
> I think a little more restraint is warranted in something like this..
More restraint than saying "unclear <i.e. to me> why ...", an exact statement about what I didn't know, which harms no one and led to several informative explanations by people who know (most of them in good spirit)?
This is what good conversation is about.
...
Anyway, the point I was making holds and is this:
Orthogonal to whether they could/should have gone around at that point, and given that they stayed on the ground after all, it may turn out that that 4 seconds of indecision (instead of pure deceleration) may have directly contributed to the fatalities at the end of the crash.
> While they were still late in calling a go-around (they should have done it before being anywhere close to touching down due to their unstable approach)
Barring a massive tailwind, they had enough groundspeed to go around at touchdown (158 kts).
I think we'll find throttling to G-A and then aborting the G-A caused the crash. If they'd committed to landing they at least wouldn't have overshot with that much energy. If they'd decided to G-A even at 00:15, they may have been well within margin to take back off.
They didn't have much runway left at 00:15 and were far slower than 158 at that point. They came in far too fast, descending too rapidly; first touch was >50% down the runway, and they didn't get the left gear down, so the spoilers and brakes didn't apply until even later.
Should have had a better approach; should have gone around before they even touched the ground; conditional on the bad approach and first touch, they should have gone around after the initial touch 50% down the runway. But they made the wrong choices at all of those points.
Yea, they couldn’t get the left gear down because they they had enough airspeed to execute a go-around!
Literally 5 consecutive minutes of making 100s of wrong decisions snatching defeat from the jaws of victory.
According to news reports, a magistrate judge at OSHA has been sandbagging an investigation into retaliatory firings by this airline (of pilots who reported unsafe practices with maintenance, CRM, training, scheduling, everything). I wonder if the NTSB will include that judge in the investigation. It seems like he or she has a lot to answer for.
https://www.cbsnews.com/news/miami-plane-crash-21-air-safety...
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> But they made the wrong choices at all of those points.
This tends to be something we see in most incidents, because the cases where someone makes the right choice at one of the points tend to not become incidents.
An interesting thought is that the more obviously bad/incompetent/terrible decisions or (in)actions were involved in an incident, the better it is, because it means more things had to go wrong for a disaster to occur (more slices of cheese in the Swiss Cheese model).
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> They didn't have much runway left at 00:15 and were far slower than 158 at that point
You're correct. When they first annunciate G-A, they've missed the chance. (They almost certainly had enough airspeed to G-A even after touching down, though.)
My question is whether throttling up for G-A at 00:15 is what caused the overshoot to extend out of the airport (versus if they'd committed to braking). This will come down to runway conditions, braking performance and the throttle responsse of their engines.
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> I think we'll find throttling to G-A and then aborting the G-A caused the crash.
Not even a chance.
> (unclear how speed didn't increase)
Large high-bypass turbofan engines take several seconds to spool up from idle (as they would be on landing) to full thrust. The 4 seconds that the thrust levers spent in the full thrust position in this accident was not long enough.
The go-around decision was far too late. Remember the engines need significant time to spool up. The decision to cancel the go-around was correct (conditional on the preceding series of terrible decisions).
They were over takeoff velocity at that point and could have bounced up in the air and waited for the thrust to come. Would have been sketchy but better than what did happen.
They were not over takeoff velocity at that point. They were at 120 knots when they initiated GA and slowed to 117 knots before aborting (again, the engines take time to spool up despite full thrust configuration and no braking over those seconds). Takeoff is at least 130 knots, I don't know for their exact configuration. (At max takeoff weight it's something like 153 knots, but at the end of their flight they aren't carrying a full fuel load.)
mind you those numbers are seconds until the cvr stopped recording. they were a few hundred feet from the end of the runway when they initiated the go around and like the other poster said the turbines do take time to spool up from idle. they were so far out of normal spec for landing that it was absolutely pilot fault but not at the far end of the runway. they were not stabilized on approach way further back about 5 min or so. (if you're not stabilized on approach you are required to go around). they even called for flaps 30 halfway down the runway which is also not allowed for a stabilized approach.
Spool up time is 8-10s on high-bypass turbofan engines. They tried to go around maybe 1000ft from the end of the runway? It was far far too late to even try it at that point.
Sadly if they had made the call earlier they were going so fast they were basically at rotation speed when they touched down so could have just pulled back and gotten into the air.
They landed flat (and the left wing refused to come down) because they tried to force the plane onto the runway. That just doesn't work. The wings are creating too much lift when you're that fast.
Disclosure: Pilot but not ATP or Jet rated.
Isn’t there a regulation for idle to full go-around thrust in a maximum of 8 seconds?
If so, it’s tight… but i feel like they should have made it if they had stuck to that plan. They commanded full power 15 seconds before the crash, and were pretty close to (if not slightly above) their stall speed (depends on load). I suspect they just needed another 10-20 knots and enough energy to climb.
> They commanded full power 15 seconds before the crash
Not 15 seconds before the crash, 15 seconds before the end of the recording. Then overran the runway 10 seconds before the end of the recording, then started crashing into objects 7 seconds before the end of the recording.
Thrust was reduced back to idle 11 seconds before the end of the recording, so just before departing the runway.
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You’re imagining a last minute perfectly executed response after what appears to be a series of gross errors of judgement. Rarely works that way.
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The fact they were even in that situation is only worth philosophizing about to a point. Because they were only in that situation due to what appears to be a series of totally unacceptable decisions that got them there. Based on everything that's come out, I'm comfortable saying as a former military aviator that in my opinion, this crash happened due to a complete failure of airmanship on the part of both crew members.
- a) Flying an unacceptably sloppy approach that put them on short final going that fast, high, and overpowered. Professionalism is being on airspeed and/or angle of attack and on glidepath . . . no excuses.
- b) Responding to a) by trying to force the jet onto the runway, when any aircrew member with half a brain should understand how badly you're going to float in ground effect when you're that fast and that overpowered. And what that's going to in turn do to your spoilers and thrust reversers that depend on weight-on-wheels before activating. Professionalism is recognizing a botched approach, swallowing your ego, and taking it the hell around.
- c) The pilot not flying sitting there like a coward and not taking the controls from the pilot flying. If someone hits a go-around criterion and isn't going around, YOU TAKE THE CONTROLS AND EXECUTE ONE. Professionalism is proper crew coordination and proper assertiveness in the cockpit.
This whole thing seems to just boil down to a complete failure of airmanship and a complete failure of professionalism all around. If I'd done that or allowed my pilot to do that, I'd expect to have had my wings pulled. If the investigation reveals more, I'll change my mind. But it ain't looking good.
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