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[Gabriel]

I don't remember a significant PIO in either of those, neither before nor after touchdown.
Proposing and PIO are different phenomena.
I suppose that you could say, linguistically, that proposing is a type of PIO because the oscillations are caused by what the pilot is doing and not doing, but it is totally different of what is normally categorized under PIO because the pilot is not doing out-of-phase control inputs....

[Gabriel]

No. You can see:
1) Significant quick rotation immediately after touch down. Ad ground effect and you have a combined significant increase of lift.
2) The pitch-down rate builds right after the bounce, not during it.
3) Large nose-down inputs after the touchdown.

This has all the signature of being exactly what I said.
If I had to guess I'd say that the pilot first freaked out with what was about to be a very hard landing and pulled up hard but then he realized that he over-reacted and freaked out again fearing a tail strike and pushed down hard. But it's just a guess....

[Gabriel]

I am sure that what we see in the video is not the result of the pilot not trying to make a smooth landing, more likely it's the result of trying and failing....

[Gabriel]

In general no. It is a myth (at least in airliners) that bounces are the result of hard touchdowns or that hard touchdowns result in a bounce, as many super rough landings with no or minimum bounce can attest.

Oleo-pneumatic shock absorbers in transport category planes are close to critically damped, so no bounce.
The biggest factor in a bounce is the late and/or large flare rotation (many times to mitigate a hard landing, and many times not succeeding hence the correlation), which causes that after the landing gear (mainly the shock absorbers) reduced the vertical speed to zero, the plane has more lift than weight. So up we go. It is more a "re-take-off" than a "bounce".


Yes, in airplanes with nosewheel landing gear configuration the main wheels are slightly behind the CG, and also below the CG, so the normal force (up) and the friction force (back) during touchdown both contribute to a nose-down pitching moment. But that effect...

[Gabriel]

IOE? That's what I thought. I was very surprised to heat that Lufthansa stated that either the pilot was in training or that it was a training flight.
Even if that's the case, that's not normally what airlines tend not release to the public. They would not want the public to know that training takes place in revenue flights, or that that fact is misinterpreted.

IOE could be an experienced captain in a previous type that is moving to a captain position in a new type and, after going through ground school and sim training, is doing his initial operation experience flights in the left seat with another experienced captain/instructor on the left seat and a check pilot + another pilot in the jumpseats. But the public and the media will say "Lufthansa was using a revenue flight with a plane full of passengers to train a new pilot and they screwed up!"...

[Gabriel]

Ok some sources, more or less copy-paste one from another. More than "pilot in training" they seem to refer to a "training flight". Again, whatever that means...
https://simpleflying.com/luthansa-bo...rough-landing/
https://www.foxbusiness.com/lifestyl...ing-lax-runway
https://ktla.com/news/local-news/dra...ttempt-at-lax/
https://www.avweb.com/aviation-news/...-hard-landing/

The Aviation Herald doesn't even have an entry for this "occurrence"....

[Gabriel]

I can't find it now but I rad somewhere that the pilot flying was a pilot in training (whatever that means, you know the media...). Apparently tat was part of a Lufthansa statement.

[Gabriel]

Interesting. Thank you!...

[Gabriel]

Of course. t's not an error on / off switch. But there are probabilities and frequencies involved. CFIT cans till happen with EGPWS. Mid-airs can still happen with TCAS. Yet, these technologies reduced A LOT the frequency of these accidents....

[Gabriel]

I am going to be extreme and propose that, until someone figures a life-saving mistake-proof method or technology, only the tower in control on active runway can clear ANYONE to use that runway, be it take-off, land or cross.

In this way not only all the traffic using the runway will be coordinated by the same parson avoiding coordination mistakes between controllers, but also all the pilots using that runway would be in the same frequency so will have a chance to detect a now-more-unlikely mistake by the controller.

I acknowledge it is not very practical since that would require frequent frequency changes by pilots taxiing, but it is a small price to pay compared to having a 777 taking off into a crossing A350.

[Gabriel]

What changed since your prime days to today? It is just my impression or we were not having anywhere near the amount of runway incursions back then? (especially ATC- caused ones)...

[Gabriel]

And yet another one...

https://www.youtube.com/watch?v=KW6lAwLy_Os...

[Gabriel]

Yes, I was thinking the same thing. Any plane can have catastrophic failures. A total loss of all electric systems would kill you in any modern plane. Not to mention the explosion of the center wing tank. The question is how extremely unlikely it is.

Seeing how fatal accidents where the pilots could not have saved it almost never happen, and how fatal hull losses happen at a rate of about 1 every 10 million take-offs for all types, FBW or not, Boing, Airbus or other, I think we are in the good way. In particular, the original A320 and the 737 NG are exactly equal in this metric.

Page 10 - https://www.boeing.com/content/dam/b...df/statsum.pdf...

[Gabriel]

I am really curious about this. Can you please elaborate? What did the instructor throw at you? Did you die because you didn't know how to handle it, or because it was an unhandable situation?
Also very curious about the fatal hydraulic logic flaw you mentioned earlier....

[Gabriel]

Before I watch it.. Is it true os is it one of those conspiracy theories?...

[Gabriel]

I am not sure if it would have not made a difference since the pilot was pulling fully back anyway. This nose down command (to simulate what happens in non-FBW plane when entering in ground effect, and to stimulate the pilot to pull up to flare) is jut a bias, not a "hard input" (i.e. not like alpha max) so it can be overridden with control inputs....

[Gabriel]

Nobody's. That was not intended. Unlike the other crazy things they did which were intentional and hence somebody's idea....

[Gabriel]

Known human factor. It has a name and all: primary - backup inversion. As all human factors, it affects humans, not just pilots....

[Gabriel]

Well, they had to, given other decisions that were made: make the pass at V-alpha-prot. That was never going to work with Alpha floor active.
So for me the real question is who's bright idea was to palan the pass at V-alpha-prot.
They could have decided to do the pass at VLS instead. Then:
- They wouldn't have needed to disable Alpha floor.
- They could have done the pass on autothrottle which would have avoided the inadvertent loss of speed below the target speed.
- They would have had more energy margin overall (for example, to pull up to avoid trees).
- The pass would have been just slightly less impressive, the difference was not worth the risk (yeah, I know, hindsight).



I think it was because it is inhibited below; 100ft you don't want the warning during the flare. Also at some point (too late) they firewalled the thrust lever which also inhibits the warning because you already took the corrective measure.

...

[Gabriel]

Alpha floor. Since they intended to do a very slow pass (at V-alpha-prot, which is below VLS, and hence has to be manually maintained since you cannot select a speed below VLS in the autothrust), and V-alpha-floor is just a hair below V-alpha-prot, they disabled alpha floor to avoid that the FBW sets TOGA and ruins the low/slow pass. That was a big factor, because they allowed the plane to go well below the intended V-alpha-prot, which the alpha-floor protection would have not allowed, and hence they didn't have airspeed to pull up.

The chain of factors were:
- The pass was intentionally done on a runway that was not the one they planned and briefed (so nobody assessed the trees as a factor)
- Alpha floor disabled (intentionally and as planned and briefed)
- Airspeed inadvertently allowed to go well below the alpha prot intended target.
- Altitude inadvertently allowed to reduce well below the 100ft target.
- Engines at idle (because they were...