bubbers44

Any competent pilot could have hand flown just fine. Pitch and power until IAS comes back. Any pilot should be able to do that. Couldn't you?

bubbers44

TT, I assume you always fly on auto pilot, right? If it can't do it you can't.

TTex600

Maybe if I post it twice, you'll read it the second time. We're talking about the information needed to fly the airplane, specifically to fly the airplane at that exact moment, not about the ability to fly the airplane.

I think 99% of the pilots posting on/reading this string agree that all Bonin and Robert had to do to live was fly pitch and power. So you got that going for you.
I also think that 99% of us want to understand why they didn't. We get it that you think they were incompetent, at least part of us would disagree. The accident pilots were all properly qualified and experienced. I for one, and trying to understand just how their qualification and experience failed them.

As to my abilities, I'll venture that you've got more time hand flying a 7n7 than I have total in an Airbus. I'll also venture that I've got 100% more time hand flying a flybywire narrowbody airbus than you. If it makes you feel any better, I'm sure you flew heading/alt/airspeed better than me. Now can we get back to chasing our tails to understand why 228 people died?

PJ2

TTex600;
"Now can we get back to chasing our tails to understand why 228 people died?"

Lyman

Bubbers44

You fall back on the same tire phrase, yet I do not believe you fully understand what you are saying.

What you mean to say, i believe, is Fly SELECTED Pitch and power...

And ROLL. You make it sound like 447 was smokin along in still air, no turbulence. They were not familiar with "selected value/Pitch". Have you flown in turbulence? Wind shear?

Select a Pitch, and it is instantly incorrect, modify your demand, and that too becomes wrong, now you are further off flight path.

The autopilot was actively manouvering the aircraft when it stopped making control inputs, and the a/c was off flight path. Had Bonin been instantly sceptical of speeds, he may have considered why the a/p quit on him. Would he have input rote values for PP? Why? The plane was moving, and we are taught to control in certain ways in turbulence. If your heavy was rolling and Pitching and you lost the auto, would you select a Pitch, a BANK, and HOLD it?

How? More importantly, why?

gums

I must be missing something about the flight control laws and the A/P.

Seems to me that A/P disconnect should result in stick commands to the system and not keep the jet rolling or pitching up or.... using last commands from Otto. In other words, no stick input then zero roll rate command or change in Nz from the basic control laws. Almost an "attitude control" mode.

So some here have advocated " don't just do something, just sit there".

My own experience in our primitive FBW jet ( have to bow down to Doze-breath about our system, heh heh) was the sucker handled turbulence really well if you simply relaxed pressure on the stick. In fact, at low level and 500 knots over the thermals the sucker felt more like an Aardvark than the light jet it was. The computers smoothed out the ride like you would not believe.

So question is: does HAL keep commanding the last A/P inputs or not?

RR_NDB

Hi,

Question made:

DW:

Quote:

Because it's one of the most difficult situations to reliably work out

An early warning alerting the crew, BEFORE System degrades was feasible long time ago. We can implement it even without a DSP algorithm. Early warning is SIMPLE.

Your answer shows:

1) Your focus is only in an automatic System
2) It was not clear to you the approach i am defending on UAS

The idea is to immediately HELP the crew to diagnose it before chances of GIGO

Quote:

Garbage in, gospel out is a more recent expansion of the acronym. It is a sardonic comment on the tendency to put excessive trust in "computerized" data, and on the propensity for individuals to blindly accept what the computer says. Since the data goes through the computer, people tend to believe it:
Decision-makers increasingly face computer-generated information and analyses that could be collected and analyzed in no other way. Precisely for that reason, going behind that output is out of the question, even if one has good cause to be suspicious. In short, the computer analysis becomes the gospel.

PJ2

Hello gums;

Re, "So question is: does HAL keep commanding the last A/P inputs or not?"

No, it doesn't. As you'd expect, AP orders stop the moment it disconnects.

However, flight control orders (C*), maintain the last pitch and bank attitudes until manual control input order a change. Roll is a roll-rate request until Alt2 Law and pitch remains a gee request until Direct Law. I know you know all this...just reviewing!

That means the controls on the wing and stabilizer are "busy" maintaining the last ordered attitudes...they're making tiny movements, but only for this reason. The AP has no input and neither does the stick so long as it is in the neutral position.

Should manual input be made, the controls will move according to such orders, while "on-the-fly" maintaining last ordered position. Once the orders stop, the airplane stays in that attitude.

I can't say whether a slight NU input is made to counter the slightly-increased gee at higher bank angles, (say, 20deg), but I know in Normal Law beyond about 33 degrees one has to pull a bit to maintain altitude in the turn.

So flying in turbulence, even moderate, is straightforward and is done with tiny stick movements because the airplane is already attempting to maintain last attitudes, in Normal Law and is doing so with exactly enough aileron and elevator. Maintaining bank isn't the case in Alt2 as we know and Roll Direct is sensitive but no big deal in terms of control. The airplane isn't about to roll over to 45deg+!...not unless the pilot does it and Bonin got the roll under control very quickly. It's a very stable airplane. It flies very well at cruise altitude under manual control.

By way of emphasizing this point, I've flown the airplane manually in turbulence a number of times (A320 as well), and really, it's not a big deal. One makes tiny inputs, just like the AP! Everybody out there on the wing is already doing their job trying to keep the last ordered attitude!

In Roll Direct (Alt2) that isn't happening but that doesn't mean the airplane is about to roll over! Tiny SS inputs again, and like I said Bonin got the hang of it really fast and had stopped the roll oscillations.

The question of Why the sustained pitch up?, may never be answered. For the record, in July 2009 in a response to stepwilk I stated that the correct response was to "do nothing" and initially got some flack for saying so mainly because the phrase "do nothing" was misunderstood as really "doing nothing", when of course maintaining pitch and thrust was what I had meant! Anyway...

DozyWannabe

Thanks for the support - appreciated. And I do agree with that point and always have.


I'm less inclined to agree with that. I'm sure some come out of the cadet programme with inadequate handflying skills and aeronautical knowledge, but I'm loath to tar a large group of people with the same brush without evidence.

It's already been mentioned numerous times that the least experienced F/O was a sailplane pilot in his spare time, so you'd expect a higher degree of aeronautical savvy than average on his part.

The point I've always tried to put across is that no matter how good you are, how many hours you've logged - handflying or otherwise - and how calm you usually are under pressure, there are times when you can have a bad day at the office regardless. Being that the flight crew aren't here to answer for what happened, I think it's fair to give them the benefit of the doubt there.

Because the pilot has the ability to solve problems dynamically in a way computers can't. It's always going to be harder at night, because you can't get a fix through the windscreen, but during the day it should be a relatively simple matter of comparing the attitude on the instruments with what can be seen outside. Sadly, the AF447 crew didn't have that option, but judging by the report, the instruments were functioning correctly through the majority of the accident sequence.

If you think the MD-80 can't throw a crew into disarray, think again:

West Caribbean Airways Flight 708 - Wikipedia, the free encyclopedia

TTex600

There was no problem to solve. The automation knew it had a bad input and decided it could no longer fly the airplane. Why not tell the pilot which input was bad? Announcing an ADR problem is not adequate.

Somebody recently said that the A/S indicators were covered with a red X. My A320 manual states that the A/S scale will be replaced with SPD

Interim 1 reads (to me) that we don't know if the FO A/S scale indicated SPD or was a normal looking tape. I'm sure someone who has all thousands of pages of reports memorized will know, but from what I can see the airplane never gave a clear signal indicating that speed inputs were suspect. I still hold that the aircraft knew that UAS caused the A/P to disconnect, it just didn't tell the pilots that little fact. The final report avoids the question by graphing CAS, not IAS. If I read these report correctly, the A/S indications were wildly fluctuating but they did not ever show SPD

The die was cast in those initial few seconds, and the airplane wasn't showing all available info during that time. It was however, chiming, clicking, honking, flashing, etc. EVERYTHING was demanding attention EXCEPT the important thing. That important THING was curiously silent and invisible. Go figure.

TTex600

There you go again.

I never said that a Diesel9 can't throw a crew into disarray. I was using the Diesel9 as an example of a raw data airplane that I've flown. I made the point that I too might well have second guessed the AF447 crew if I only had raw data/analog experience; but now that I have Airbus experience I won't second guess. I assumed that pilots would understand the comparison.

That's nothing more than a little glimpse of who I am. Would you like for me to start analyzing you? Maybe we can switch places and I can mis-characterize your positions for a while. That might be fun. Lucky for you, and Tullamarine, I'm heading off into vacation. Enjoy.

TTex600

Thanks. On the 320, the SEC's don't have any aileron input, that's my experience. I didn't mean to muddy the water. (I did look it up :-) )

gums

Yeah, PJ, like I thought.

The one thing I question is loss of roll rate command in Alt 2. Looked to me that as we go thru the reversion sequences we lose bank angle limits and you have to add some back stick as bank angle gets to maybe 20 or 30 degrees.

I keep seeing "attitude" versus rates - Nz and roll rate. True that the jet may seem to "lock" on an attitude except in "direct", but that's what we saw in the Viper except for the pitch attitude correction to the Nz. The basic laws are still Nz and roll rate until in "direct", right?

I would dearly love to get some of the 'bus drivers up in my trusty Viper to show them how our system worked and "limited" you ( hate that word "protection", heh heh). Very small pressures required unless hassling in a dogfight. Our pitch gradient was about 4 pounds per gee and all pressure, not stick movement even after they increased the throw to 1/8 of an inch. The roll command had a limit I was not aware of until my LEF folded up. So HAL was commanding zero roll rate, but turned out I had another pound and a half of pressure left to keep the wings level. Gotta admit it was disconcerting. I also kept the speed up, as previous dude crashed and burned while getting slow during his "flare" for landing. He ran outta air molecules to help roll, and I prolly got ten knows slower than I should have, but my HUD tape shows that it looked pretty good to me.

The second thing I would demonstrate would be the AoA limiter. Pull as hard as you wanted, but even on STBY GAINS when air data went FUBAR, we still had that working for us. By the time we got to 27 degrees AoA we were at 1 gee and could pull as hard as you wished, but that was where you were gonna be.

The biggest difference between the 'bus pitch and ours was the correction for pitch attitude. So the 'bus actually reduces the Nz command, but ours kept striving for whatever gee we had trimmed for, normally one gee. Hence, at extreme pitch the one gee command kept raising the nose and we could fly into the "deep stall" with a neutral stick.

DozyWannabe

@TTex600:

I totally follow what you're saying - however, the idea that the systems weren't relaying useful information (in that it could be processed by the flight crew) simply does not square up with the PNF saying "We've lost the speeds" at approximately 02:10:15 on the CVR - at least to my mind.

And I'm not trying to analyse you or anyone else. The fact is that every airliner from at least the '60s onwards has had some form of electro-mechanical device between the raw data and what gets displayed on the instruments - whether that device is as simple as a three-way switch or a more complex setup, such as a digital voting mechanism.

No matter how old-school or modern the system, the onus is on the crew to work around the problem and try to overcome it. The gradual shift from steam-gauge to digital technology has altered the nature of the problems to be solved - that much is certain. Also certain is the fact that the accident rate has consistently come down since the introduction of the new technology. What is less certain is how to approach the new problems that raised their head in that time.

I don't think any of us will get a satisfactory answer as to why the PF pulled up. Because his display was not recorded and because he did not survive we will never know conclusively. From my point of view, even if the pull-up input was triggered by something he saw, far more important to me is why the PNF did not feel he had the authority to command the PF to hand over control while he was waiting for the Captain, and to a lesser extent, why the Captain did not delineate the parameters that would have given the PNF the confidence to do so when he went for his rest period.

Lyman

"I totally follow what you're saying - however, the idea that the systems weren't relaying useful information (in that it could be processed by the flight crew) simply does not square up with the PNF saying "We've lost the speeds" at approximately 02:10:15 on the CVR - at least to my mind."

Wrong, it was 2:10:16. For eleven seconds the PF may have been following duff data. Your statement is nonsense, unless you ignore the possibility that eleven seconds means nothing, which you would do....



PJ2 you say the a/c would not keep rolling after ap loss, but I think you mean in the context of Normal Law. In Roll Direct, it would keep rolling, NO?

You mention the PF quickly controlled Roll, so I assume you mean his input was appropriate.

The Nose Was Low. We know it was trending UP, but he may not have been cognizant of that, hence the Pull.

It is probably noticeable that I am trying to establish that the PF may have started his manual handling with inputs that while demonstrably inappropriate, might have seemed correct given the conditions.

It is also possible that PF believed the Flight Law was NORMAL LAW. Since this would explain perhaps his apparent ham fisted inputs, I go with that conclusion, for purposes of discussion.

It has always been a challenge to separate conclusions from their bias, and their consequent growth into 'fact'.

I readily admit to looking at everything, however I do not represent that they are conclusions, especially as they are absent from BEA reportage. BEA suggests ICE, the thread assumes Fact. The pilots seem somewhat incompetent, that becomes fact, and subject to constant repetition.

My assumption is that this accident became almost instantly un recoverable, due to many factors. The proper discussion involves a look at everything, even if it is somewhat exculpatory, imho.

DozyWannabe

It was 02:10:15.9. How you read that depends on whether you're working in decimal places or significant figures. PF calls for control at 02:10:06.4, meaning that it's more like 10.5 seconds.

We know that the CAS was actually indicating *low* speed rather than high, so increasing pitch angle does not tally with what may have been displayed on the speed tape. We know that it's likely that the erroneous drop in altitude might have led to a pitch up command, but not of that magnitude and not for that length of time.

No. The flight surfaces would return to neutral, and the aircraft would passively attempt to hold bank angle in the same way as a traditional airliner. It won't actively try to hold a lateral flightpath.

With all due respect, that's pretty rich coming from someone who's thrown accusations of broken vertical stabs, snapped jackscrews and stuck autopilots at the aircraft without a single bit of supporting evidence!

(I know my position is largely theoretical too - but at least the phenomena of pulling up due to startle effect, confirmation bias and flight deck command gradient are known and have been studied!)

That's how you're choosing to read it. The crew made mistakes in terms of handling and CRM, certainly. But that's a long way from claiming they were generally incompetent.

Lyman

You have never wanted to accept my pov, fine. My purpose in the discussion was to move some people off of precipitous thinking.

No. The flight surfaces would return to neutral, and the aircraft would passively attempt to hold bank angle in the same way as a traditional airliner. It won't actively try to hold a lateral flightpath.

They were deflected?

HazelNuts39

Figure 64 of the final report (download separately from the BEA site) shows in a simulation what the airplane would have done without pilot input with reconstructed wind.

DozyWannabe

It's got nothing to do with who the POV comes from, all I ask is at least *some* evidence to back it up.

To the best of my knowledge, very few folk on these threads ever did so - in fact none who stayed around to discuss things did. Even those who actively bemoan the quality of low-hour pilots today have seen it as a system-wide issue rather than pointing the finger at this particular crew. The BEA wrote up the factual evidence, were very clear about system-wide issues and also did not disparage the crew. Throwing random "what-if"s into the mix serves to harm credibility as far as I'm concerned.

Lyman

HazelNuts39 Figure 64 of the final report (download separately from the BEA site) shows in a simulation what the airplane would have done without pilot input with reconstructed wind.


So now we know.... What a relief. When did Bonin know it?