JD-EE

HazelNuts39,

I am rather wondering what the performance of BUSS might be in "unusual attitudes". It is intuitively obvious to me that if the plane can be expected to stay flying "normally" on pitch and power one could work backwards from altitude, pitch, and power to get an airspeed indication when the plane is more or less in a steady state. At reduced accuracy it might even be able to make good guesses while altitude is varying. What's not obvious is what could have been derived from the plane's movements and power settings once the upset had begun. At that time the velocity vector becomes more interesting than mere speed.

BUSS would be good for getting through an upset period if you don't do anything stupid.

JD-EE

rudderrudderrat, "Pilots can only sense accelerations - not speed. The sensation of high speed was due to the unusual air noise around the cockpit sounding like they were going very fast."

Indeed, and they're not as good at it as they think they are. He was leaning back. That felt like acceleration to him. The comment made makes it seem like he was pulling back on the stick to get the nose up to slow down and it wasn't happening. The acceleration was continuing. His brain froze solid.

A full motion simulator can show you this effect happening. And if the training program includes a module to explain how such simulators work maybe then the idea that you cannot trust even the pressure on your back or seat when flying with no visibility at all outside the plane. That brain freeze prevented him from recognizing the stall. (Darnedifiknow what led the PNF to be so meek about breaking through PF's fog. It cost him his life, whatever the reason.)

JD-EE

Now ask the important question. Could the THS deliver ENOUGH lift at any setting to eventually produce an ND attitude? It's not sufficient that the THS and elevator produce lift. It must be sufficient lift to materially affect the orientation of the plane.

As a thought experiment a stiff sheet of cardboard held outside the car window tilted at 60 degrees produces some lift. But it's very small compared to the lift when it is nearly horizontal. And it depends highly on the velocity of the car. Memory if playing with such stuff when I was MUCH younger suggests the curve involved is not a simple lift proportional to some constant times the cosine of the angle relative to horizontal. The upward force needed is, however, proportional to the cosine of the angle of the plane to horizontal.

Can the THS/Elevator combo win this race? I don't have the data to know one way or another. I am sure simply generating lift "ain't enough."

rudderrudderrat

Hi JD-EE,
I disagree.
He would know that with a nose up attitude around 15 degs that the sensation on his back felt normal. Most of the time he held around 15 degs pitch - they didn't exceed 20 degs of pitch at any time. If he was confused about acceleration and pitch attitude he would have pitched up even higher.

Pilots recognise the difference between horizontal accelerations felt on take off and the sensation at some nose up attitude - by using the PFD.
This crew simply used the wrong pitch attitude.

I think he's used the pitch attitude he's associated with TOGA power. OK at low level - but completely inappropriate at cruise FLs and they never recognised the fact they were stalled.

JD-EE

jcjeant, you're annoying. You're starting to ask my kind of questions.

(grinning ducking and running ---->>>>>> that way!)

JD-EE

Really ---

I wrote and posted 520 BEFORE I wrote and posted 519. Something glitched!

Spooky!

JD-EE

What do the pilots know that the computers don't already know? In fact everything the pilots see is filtered by computers. The AF447 pilots were just as blind and bereft of real data as the pilots. So there really is a valid question here. Why DID the pilots have to take over?

The only valid excuse that comes to mind is that the designers did not know this particular failure mode existed. Until this crash the doctrine was that such errors could not happen.

Now, the computer actually has more information than the pilots saw, it appears. At the very least it has AoA. It also has GPS, raw and processed and the inertial system that it can use to work with. It HAS altitude. It never lost it. So it can monitor its pitch and thrust and fiddle both to maintain altitude. It might be a "lumpy" process. But it would keep the plane flying. The pilots may have had the GPS/INS data displayed somewhere. It appears it was as little in their scan pattern as the trim wheels. So it might as well not have been there if it was. The computer would scan these things if the software design had it doing so.

JD-EE

rudderrudderrat - that's the theory. His actions and words suggest he plain forgot, fell back on seat of the pants flying, and died.

02:11:40 "I have the impression (we have) the speed."

How did he get that impression?

rudderrudderrat

Hi JD-EE,
Good question.

If the Autopilot could have remained engaged controlling both pitch and roll - but with a Health Warning such as "ATT", then it would have freed up more brain cells.

What is the point of playing "Keep the Wings Level" with roll direct when faced with UAS?

I would guess from the unusually loud air noise. If they thought they were accelerating, they would have closed the Thrust Levers.

Lyman

JD-EE, rudderrat. He wanted evidence for overspeed, he found it, and acted accordingly? Brain Lock, dangerous, lethal, at times.

Sometimes, and I have been guilty of it here at times, The human Brain makes up its mind, then looks for evidence in support of conclusion.

Doubt everything, especially one's own opinions. Advice to self.

"I have the Impression...." Linguistically, that is a statement in want of a supporting opinion. If supported by either of the other two pilots, he is affirmed. Then the group can act. PF is too fond of the plebiscite, the election. "Wrong, My Airplane....."

Like the AD's Three, a vote, then?

Chu Chu

JD-EE,

You're the expert on this, but trying to program the computer to recognize every possible failure mode (and to avoid confusing them with each other or the failure modes you inevitably failed to anticipate) seems like a much taller order than just progressively shutting down the automation when it becomes apparent something's wrong. Maybe something you could do if starting from scratch today, but not with the technology the A-330 was designed around?

PJ2

Yes, I agree with that - a nominal 5 degrees pitch, held fast and gently achieved with tiny stick movements, and thrust levers in the CLB detent would not stall the aircraft.

PJ2

One way of perhaps making a change which retains the essential and necessary actions in the original drill is to modify the qualifying condition at the start of the memorized drill, which is, "If the safe conduct of the flight impacted". There is little guidance on how to make this decision in a hurry. In some explanations, the "safety of the flight is impacted" if all three airspeed indications fail". While such an assessment is probably a wise and accurate one, I disagree that the automatic response to this qualifier in the drill should be a pitch-up to 5deg.

The drill was originally conceived to deal with pitot or static system failures close to the ground, the takeoff phase being the obvious and most critical phase. The memorized items, as I have argued, cater to the takeoff phase, and, I have argued, the "Above FL100" caters to the climb, perhaps even out of high altitude airports, but not to cruise levels where the aircraft is already in stable, level flight. I submit that it is a mistake of interpretation and lack of clarity in the drill, to execute the 5deg pitch-up using this qualifier. This qualifier is followed by three items and the statement, "When at, or above MSA or circuit altitude, level off for troubleshooting". Well, one is already well above MSA and is already levelled off. Why divert from that qualifying condition, only to return to it "quickly", as the "How to do this drill" notes require?

If the memorized items are to be correctly placed and the subjective, very individual assessment as to whether the "safety of the flight is impacted" avoided if the memory actions are qualified not by "the safety of the flight" but by flight phase and by altitude. Then the drill is much more clear as to what actions to take. Qualifying by flight phase and altitude are the first memory items after the "safety of flight" qualifier anyway.

So it might look like this:

DRAFT - DO NOT USE - FOR DISCUSSION ONLY:


As Clandestino has pointed out, these drills and checklists have been created carefully by test pilots and others who know this work thoroughly. The suggestion for change will have implications not imagined or considered and clearly needs examination by many others. But the basic notion is removing the initial qualifier to define more precisely, where different behaviours, (crew responses) will occur. I think that confusion and the training resulting from this confusion is at the heart of the initial pitch-up - what cannot be explained in this view is the immediacy of the response and the absence of SOPs and CRM.

Changing drills and checklists occurs all the time as new knowledge and experience emerge. This is normally done through meetings between checkpilots, standards pilots, flight safety/flight data people and so on and is otherwise a process with heavy vetting of such changes.

In fact, the UAS memory items and ADR Checklist have perhaps half a dozen iterations from around 2001 on - the first drill did not mention "levelling off" at all and was a straight response to the Birgenair and Aeroperu accidents. However, the B727 pitot-icing event pointed out by a poster recently, was not considered, nor, I believe, were pitot failures at cruise altitude until after 2002 or so even though such failures had been occurring since 1996.

There are other serious matters at hand which this accident has made clear. But the accident sequence began with the instant pitch-up, with no SOPs followed, and it is important to establish why this occurred and to take measures to examine and change those reasons.

HazelNuts39

Which computer? The AP and A/THR disconnected, and handed 'control' to the FCPC, which reconfigured to Alternate law. The purpose of 'pitch and power' is to "keep the plane flying", not to maintain altitude or airspeed (in UAS and in turbulence). The FCPC does just that - maintain pitch and power. Why can't it maintain bank angle?

Ian W

JcJeant
There is another question - to what extent do simulator exercises provide sufficiently real training for emergencies?

There is a considerable psychological impact that the human factors people seem to have ignored. That is that transferring computer game simulator learning into handling 'real world' emergencies does not work well with all people. In the 'old days' before clever simulators all such training was in the air and if a trainee repeatedly 'lost it' under pressure it became immediately apparent. This weeding out will not happen with sim rides where trainees learn to pass the sim ride.

It could be said that the only reason that pilots are required is for when the automatics fail.

Several posts here have statements like: "The simulator does not perform like the real aircraft after a stall" or "the simulator cannot behave as the real aircraft does outside the normal flight envelope" and even "the simulator does not fly like the real aircraft in Alternate Law"

So the simulator is being used to train pilots in how to handle emergencies, upsets and LOC, despite actually not behaving like the real aircraft in emergencies, upsets and LOC?

The current approach of only using simulators for training pilots to fly simulators does not seem extremely logical. I am sure that the accountants love it.

BOAC

PJ - the problem with your suggestion is that it does not cover all bases, in that with a total baro data failure one could see a crew 'floundering' for a pitch attitude, whereas 5 is SAFE, will not cause a stall from steady cruise and will then give time to enter the trouble shooting phase with pitch/power from the QRH. I really see no need to change OR to worry about the definition/interpretation of 'danger' either. It will work, it will give 'breathing space and it is easy to remember without having to try and find a pitch attitude that produces a steady GPS altitude! Heaven knows the ship is complicated enough without adding to it.

Ian W - indeed - and the exercise is self satisfying in a circular way, since it can be demonstrated that with improved sim time and training sim performance is improved, and it is there that thankfully 99% of our aviation 'nasties' happen. When they happen in the real world we discover the holes.

Zorin_75

To my understanding, PJ's suggestion should be in effect exactly the same as the current procedure, just making it easier to decide how it should be applied...

http://tinyurl.com/3or72nd

PJ2

Thanks BOAC. Yes, I knew there were "holes" and perhaps that's one. The intent is to examine the drill, for all reasons given.

PJ2

Zorin_75;

Yes, my thought was to keep it as close as possible to the original. Thinking about it, BOAC's critique applies equally to the original drill.

gums

I am disturbed by some here that believe you can handle an emergency situation or an "upset" ( love that term, and cracks me up and guess it really means "WTF?, over") by following rote, memorized procedures for more than a few seconds.

I am a "professional pilot" or would not have joined the fray here. Granted, folks like me and RF4, Wolf, 'bird, Smilin', et al flew way beyond the envelope I would expect for a pilot hauling SLF and trying to get the zillion $$$ jet safely to the destination. Nevertheless, we had our "boldface" procedures to rely upon for the first few seconds. Then we tried to figure out exactly what was going on and what we could do about it. The ol' OODA loop.

Make no mistake, great cockpit displays and unambiguous caution/warning indications are extremely important. I don't believe the AF447 crew had such.

The stall warning implementation deeply disturbs me. No "stick shaker" gizmo, no clear display of AoA, etc. AF447 was above that 60 knot speed that disregards the AoA, and even if the pitot system was FUBAR and output was zero, the AoA should have been provided in a clear manner to help the crew. Some jets have very benign stall entry characteristics, preceded by mild buffet sans wing rock, little yaw moments, etc. hence the 'stick shaker/rudder shaker" and other gizmos. They told you, GET THE NOSE DOWN!!!

A few here have noted that at high speed the AoA only needs to be changed slightly to get really large changes in gee and pitch changes. True, but the 'bus FBW major pitch law is mainly gee, so big deal. OTOH, once getting slower and approaching or actually in a stall, the AoA is the best gauge, and friend, you have!! It's also super when flying an approach and something is awry with your weight versus approach speed calculations. in other words, it tells you something is wrong. And remember that the plane flies on AoA and not airspeed ( which can go Tango Uniform, as has happened numerous times in the 'bus"). i might add that the Viper AoA versus gee command function reduced available gee command from 9 to 1 as our AoA increased. So at max AoA we could only command one steenkeeng gee!

So I shall still not let Airbus off the hook. Neither shall I let the crew off the hook.

I would pray that current and future crews have a requirement to fly the jet in the alternate laws under strict supervision. Not depend upon simulators. Actually "feel" the plane and maybe even the buffet associated with an approach to stall.

Sorry if I have ranted.