It isn't about whether the AOA's were faulty because they weren't. No fault nothing to detect. Something external to the sensor affected them.

This is why accident investigation must encompass more than the flying aspect.

The aircraft had been painted and washed. This involves following strict procedures for good reason. You can affect sensors in an unpredictable way.
Just as pilots have procedures which must be adhered to so does everyone else.

The aircraft departed and for quite a bit of the flight everything was fine, then something happened to 2 out of 3 AOA's. The AOA is an extremely reliable sensor so 2 behaving badly at the same time is unheard of. This needs investigating. It isn't about my input is more worthy than yours, its about finding out what happened here and what happened involves more than just flight crew.

Something was technically wrong with that aircraft, we need to know what and why otherwise it will happen again.

I think you should read my post.

And while i'm at it DW, the simple facts of the matter were that in the final seconds of the flight, while the captain had the side stick in the full nose up position the elevators were full nose down. This may have been a result of summation (in that the stabiliser was full nose up) who cares? If a pilot is ordering full nose up on the elevators, shouldn't he get it?

Absolutely, SC, hence my #1169. I must be remembered, however, that once all the designers and engineers are done, and something is wrong with what they have done, that we have, for the foreseeable future at least, one human there who SHOULD be able to do some old fashioned flying (that is without software) and save the a/c and lives.

Yes, if something prevents them doing that it must be investigated and designed/engineered out - see para a). I have yet to see any evidence that such existed, but the F/O's sidestick trace would be of interest to me - or have I missed it on the traces? On an AB, does the 'Captain's sidestick position' always represent that or the master stick position?

EDIT: Picking up on Scotty: I think from what I have learned the sidestick is a rate demand rather than a position demand? Hence if the nose-up stab effort (at 263kts) was producing at least the designed max pitch rate, the elevators would be in opposition? Whether the airframe would have withstood max elevator as well I do not know. The nose was pitching up fairly rapidly after all at impact

Once again we appear to have the excessive stab trim/pitch couple causing the major upset. Is it time this was eliminated in the software? Perhaps some over-rideable limit on trimming range? As we know this is certainly an area where crew training needs to change.

BOAC,

For the pitch control, the flight law is a load factor demand law.
Most probably, for the final dive, the pitch demand was limited by the load factor protection.
This could be the reason the BEA was not interested in publishing the vertical acceleration graph.
... could be more fonded that we might think.


The F/O's sidestick trace would be of interest to me too.
Who thinks the F/O remained of ice in those extreme attitudes ...
Me being in his seat it would have been "dual input" all over the place, or at best "priority right" ... if I could stay cool enough.

Thanks for the clarification, Conf. The emphasis has to be on how they got to 51 degrees nose down at 1620' (a real 'coffin corner!) and not what the controls did thereafter.

You're right BOAC - I suppose 97°of bank might have something to do with it...
Re sidesticks - there is no "master", the inputs are summed algebraically unless one pilot presses and holds the "takeover pushbutton" (same as AP disconnect pb). You should be able to tell from the FDR trace whether there is a dual input in Direct Law (if the control positions don't accord with capt. sidestick position) - can't see one. But in Normal/Alternate Law I reckon you need the FDR info on dual input.

What interests me is the lack of CVR information in the BEA interim report once it all went wrong- I would like to know whether the crew said anything about:
a) being in Direct Law
b) moving the THS from fully nose-up
c) why they raised the gear
d) why they looked at ECAM HYD system.
I like to think the final report will tell us....

Indeed , it proves two things - use of aileron on a stalled wing is not a good idea and the best way to drop the nose is to apply lots of bank.

I suspect the CVR is not 'pretty' and may therefore not reach the public domain.

Do you deduce that they deliberately 'looked' at the HYD page or is there some automatic call or could someone just have 'missed' on a selection? Likewise why the ENG page later?

This is still nice to understand why the elevators did the opposite to the sidestick ... s(?) request.
Now, 17 seconds earlier, the airplane was at 3800 feet in a 57 degrees nose up attitude and virtually no speed. The emphasis could be on how they got there first.
It is amazing to consider that for a full minute, that airplane was out of control before it finally crashed.

The most interesting part should be to analyze what role played those two frozen AoA sensors in this flight.

- well, I would think as per my para3 (italic) in #1177 that the elevators were attempting to limit the g caused by the THS setting?

Regarding 'how they got where' the '57 up' is all part of the route to 51 down. I think we are all pretty convinced, are we not, that the '57 up' was power/pitch?

We are ... but the power/pitch was not manageable due to the excessive THS up position which got there because of the faulty AoA sensors that were telling the same lie and silently discarded the only probable (?) reliable AoA data.

BOAC
Good question - no thoughts either way now, although my previous post assumes they selected it, it's just one of the events that the CVR might explain a little. The HYD key is next to the F/CTL key, but if that was the target I would expect it to appear almost immediately after the wrong selection was realised.
Re the survivabilty of 50°pitch, to me it all hinges on the THS - was it stuck or did they just not move it (Direct Law = Manual pitch trim)? With the trim in a more normal position and the a/c in Direct Law a recovery should have been possible - and they probably would not have reached that attitude and the resultant low speed in the first place.

"the parameter is recorded every four seconds" says the report and 4 seconds later displays 'ENG'? Does that mean anything to you?

In a Boeing with competent pilots this could not have happened. Once again I think automation took over and the pilots were along for the ride. They probably were trying to use the proper recovery but automation overrode their inputs. The pitchup was probably a result of too much thrust being generated at critical speed. The pilots on a Boeing would have reduced the power to control the pitch and recovered with little problem. Pilots know how to recover from low speed stick shaker situations. They also know how to not be (to) agressive with thrust until they can control pitch.

too, not to. I hate those errors.

Like in AMS ... ?

I think p51guy wrote.... "competent pilots"

bear

More Boeing drivel. So any crash that occurred in a Boeing occurred because the pilots weren't competent? And anyone who flies an Airbus isn't aware of the thrust arm with underwing engines? Or standard stall recovery?

Anyone on a public forum making such comments should first start off with "my experience on both types is............"

So P51 guy, were the pilots in the Cali accident competent?

AI v BCA drivel
 

I feel the occurrences of multiple crashes over the years of AI aircraft during training/test flights point more towards a misunderstanding of the protections and automatic functions of the computerized flight control system rather than indicating a critical defect in design.

A deeper understanding of the FBW protections as they apply in complex degradation scenarios seems to be called for if we are to avoid future incidents and crashes.

The question "Why does it do that?" should never be a part of a crew's standard vernacular.

Being competent doesn't mean you can't make a mistake. The Cali captain was considered quite competent but no one will deny they made a huge mistake that night. Being competent means you understand how to manage an aircraft properly and can demonstrate it. CFIT has been accomplished by quite a few crews considered competent.

It wouldn't have happened in an A320 with competent pilots either. Or an Embraer or a Bombardier or a Piper.

No doubt the accident crew was competent, but unfortunately not for what they what they got themselves into. As with the "competent" Cali crew in P51guy's post, they made a huge mistake that day. It might be borne out by the CVR and FDR that through most of the flight, they did things well. Save for one. And that one thing was the one that killed them.

Digging up Cali is a sign of desperation, the causes of Cali are well understood and had zilch to do with anything discussed here.

Maybe we should be discussing Nagoya... or all the other mode confusions/envelope protection incidents/accidents.. of which there are damned plenty... and none of 'em Boeing.

This would not have happened to a competent poster - he/she would have simply edited the previous post...
Edit: so that we knew which "to" was referred to.

You can edit a post after submitting? I have never flown an airbus so was just saying letting pitch because of too much thrust reach an uncontrollably high attitude without quickly reducing power before reaching an unsafe attitude wouldn't be possible in any of the 72 different types of aircraft I have flown. The only way would be to let the power stay high and not do anything about it until it was uncontrollable.
If this line is here I now know how to edit and must be declared worthy of editing old posts.

Whoops ! Define competent.

This is getting ridiculous, better things to do.

This discussion mentioned automation and protections of which the airbus has lots and the most modern Boeing has very little. Still trying to figure out why an aircraft would be designed so that you could fly with max thrust and the speedbrake out. Boeing designed it like that why exactly?

I don't think any air transport aircraft over 50Tons irrespective of who designed it could have been in that training flt energy regime and recovered within the height available.

Advancing power levers on a 757 on the ground will retract the speed brakes automatically. It was to assist in a go around after touchdown. Boeing didn't deem it necessary in flight. Procedures were changed after that incident to verify speed brake retracted on all GPWS alerts. It might have let them clear the ridge but it would have been so close.

I flew that night in the same area and with no moon coming over the hills you could not see anything with unlimited visibility. A month later Cali offered us the same straight in approach down the Valley they were offered and I declined it to overfly and do the ILS. If it wasn't for their crash I would have taken it but it was an easy non precision approach and shouldn't have ended up like it did.

Why . . . ?

We declined it because a month before almost 200 people died doing that. It was a safe approach but it was too close to the tragedy and out of respect for the dead we didn't want to show how it should have been done. We respected the crew that died that day and proving it could be done easily didn't seem appropriate. It took 5 minutes and we had an ILS approach at night.

Most of the passengers probably knew what happened the month before and would have preferred what we did. Flying into Cali dozens of times that was the only time I was offered a straight in approach.

Due to the faulty information sent by two of the AoA sensors, it is probable that the speed tape as presented to the crew was erroneous, bringing some confusion. The indicated airspeed was correct, but the protection speeds which are based on aerodynamic data were misplaced.

http://i35.servimg.com/u/f35/11/75/17/84/nz_spe10.gif

The FACs have been duped by the AoA sensors for the representation of the protection speeds on the PFDs. The ELACs have been duped as well, as the protections did not activate.

Point to be clarified ?
 

1. Page 9 of the report mentions that the THS went to the pitch-up stop.
2. Page 20 ... that the THS moved to 11.2 degrees NU and remained in this position.
3. FCOM mentions that the maximum THS deflection is 13.5° nose up.

What's going on here ?

Airbus denial?

For a full 25 seconds, the Captain sidestick has been almost constantly to the full forward position ... did he say anything on the fact he was trying to manually move the trim wheel ?

The CVR data published by the BEA are too little. Many things have been told on this flight deck except that the NZ pilot was putting pressure on the XL crew to proceed with the alpha floor test and the XL crew was unprepared to do so ...

There is a possibility the crew was also facing a STABILIZER JAM.

The point surely still remains that in the middle of all this the a/c was flying quite happily unstalled but was then allowed to pitch up out of control. I believe 7 nose up and 144kts was achieved at one point? It would seem (with the usual 20/20) that had the power been pulled back then there would have been some time to think.

True, but that would be only the second thing to try after an attempt to trim didn't work. As you say, at that point the situation seemed under control, probably was also the feeling for the pilot, but the very temporary release of the stick at time 15 45 20 has been fatal.

Question remains : During the first 10 seconds after stall warning, airplane was still in normal law, sidestick was mainly forward, but the autotrim didn't move ... Why ?

Was the THS jammed ?

Indictment of the button pushers
 

Airbuses are fine machines when ever thing works properly. But when faults happen, they don't always clearly annunciate to the crew what's wrong in a clear fashion. For example, the predecessor aircraft the A310/300 the trim would move without the stabilizer motion audio sounding when it was on autopilot.

Why?

As Captain eating dinner, I'd like to know when the damn tailplane is moving. Old boeings always gave me a visual, moving trim wheel or audible trim motion horn that I could see out of the corner of my eye or hear softly in the background. I'd get a warning that something was wrong. I'd sure like some warning that a runaway stab is likely in progress. I'd sure like some noise to know if the autopilot is over trimming because a sensor failed. It would give me a few extra seconds to worry that a trim miss match with the THS is possible and I would be on guard for a wild pitch up or down when I disconnected. It would direct me to look at the pitch trim to see if it made sense. On the first airbuses, the motion was only audible after five seconds or so. It was way too long a requirement, and since the trim wheel didn't move, and the autopilot trim system trimmed in short bursts most of the time, I never knew when the machine was trimming; so I couldn't easily detect cross controlling the trim on the tailplane.

Ah yes, Thrust Latch and a wild desperate struggle between the auto throttles and the FCP (who apparently were different departments at airbus.) The airbus "Bob Hoover" tailslide pull-up never made sense to me either. The silly thing would go to deck angle 90 degrees straight up if you let it. All it knew was to protect overspeed at all costs. And all the autothrottles knew was full rated power. It never occurred apparently to the french flight control programers to try to sync the disparate systems together? All I could figure out was that the bird didn't have a reasonable target deck angle to shoot for, since it was always hopelessly behind in the pull up (gradual for pax comfort you see), and would invariably always overspeed, requiring desperate airshow elevator and trim actions to keep from busting red line. Or maybe the original Autopilot logic was designed for smaller engines?

All I know is that Boeings, Douglas, BAe's, never did this to me. With Airbus however, you had to always be on guard to disconnect both A/P and A/T anytime Outto was groping his way through the air.

The brands are distinctively different, despite some of the "airbus denials" you read on these threads.

I have no experience on airbus sidestick models, but I always hated sidestick airplanes for the simple fact that you can't switch hands. What if you need to adjust your seat and wiggle: there you are; when hand flying, cemented into position like a statue unable to drink coffee with the right hand if you're an F/O or unable to turn your approach plate with your left hand if you're a Captain.

On jets with a yoke I constantly would switch hands as one become tired, use both for the takeoff, push on the tops of the ramshorns for more leverage, "fly on the trim" button alone.

In hand flying, you receive a real "feedback" with the physical motion of a large control column lever that a pressure side-stick just can't duplicate. Humans, studies have shown, are poor at monitoring automation or at judging pressure. But more importantly, being able to physically see with your peripheral vision what the other guy is doing with the huge yokes of the old Boeings was a huge benefit to understand what inputs your cpt or f/o is putting in. Instead of trying to figure out what he's doing or not doing over there in the airbus corner, with big throw/large travel yoke right next to you, there is no doubt.

And over riding the other guy is instinctive if he's losing it. You don't have to think about "Gee, how do I assert control of this thing?; push a button wait a bunch of seconds and bla bla bla.

There isn't time for that crap. In the Boeing control columns world, if he doesn't let go the differing forces with snap the two apart leaving the capt in control. But it never goes that far; that never happens because handling pilot can already see the Body English of the other pilot leaning forward and grasping the yoke, indicating that he's about to take over because he's unhappy with the flightpath.

What happens, pray tell, when the flight path goes bad on a democratic Airbus with sidesticks? Take a survey? Take a vote? Split the difference? Push buttons and hope to regain control? Who the hell's flying the thing? Both of you? Is it the autopilot or the guy guarding his secret stick with his arm in a crack? Nobody knows! Maybe he's dead over there... Slumped down on the armrest with crumby posture like he's donating blood at the Red Cross....

Side sticks suck, they are the bygone relics of a single pilot age. They belong in tandem fighter jets, not multi-pilot airliners, imho. You should be hand flying in a conventional fashion, adding back pressure in the turns on a regular basis; preparing for the day when the AOA sensors, or all three Pitot probes fail like with AF 447, and you will, (gasp), have to use your hand flying skills in manual law.

On that day, when all those nanny protection devices go on strike at the same time because of simple sensor failure, you will be glad that you did not count yourself in the ranks of the great button pusher pilots of tomorrow, so many of who post here claiming just more training or "understanding the systems better" is all that's required to avoid a similar fate. You will instead, be able to actually hand fly your way out of a wet paper bag, if that is required of you.

No one will thank you, and the public will assume that these new computer machines just fly themselves. You however, a real pilot, will know differently since you recognize and uphold a one hundred year old tradition of actually manually hand flying the actual airplane on the line! :eek:

Or alternatively, you can lie to yourself and parrot the airbus marketing hype that flying is safer not worrying about flying on the back side of the power curve since alpha floor is here to protect everybody.

It's your choice.

Crunch - out

Crunch...

Putting aside the various (and often vehement) opinons re AB v/s Boeing, your post above is a superb summary of one particular aspect of human factors and human performance. Well done.

grizz

cant we change the record on this subject.

757 with blocked pitot probe crashes
757 with blocked static ports crashes
Trident stalls on take off out of heathrow, crashes
Korean 747 exceeds bank angle due to faulty instrument, crashes
A320 stalls during test flight at low level, crashes

It may surprise you but it ain't the technology.

SC...
With all respect.
If you're referring to Crunch's post, (or mine) I think you missed the point.

Basically, if you don't understand the way your aeroplane flies, stick to a less-demanding occupation, I would suggest.

Why on earth would you want some stone age trim wheel rattling back and forth every time your autopilot makes a trim change? Just because that's what it did on ol' Bubba Boeing's 707 isn't really a legitimate reason.

Ah, bless.....

You don't need to cling on to the sidestick like grim death like you apparently did to the yoke in your stone-age Boeing. But if you need to use that hand for some other reason and really are petrified of letting go of the sidestick, then the words "You have control" spring to mind.