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Centaurus
18th Apr 2010, 11:38
A friend of mine who flies A320's said that Airbus had just published a Memo to all Airbus type operators on the subject of training for unusual attitude recovery in the simulator.

Basically it said that unusual attitude training should not be taught in simulators and that a theoretical knowledge of Jet Upset recovery techniques is all that is needed. Rather like saying to a child I won't teach you how to swim but I will train you not to go near the water, instead.

The rationale appears to be that because aerodynamic forces associated with Jet Upset cannot be reproduced with proper fidelity in a simulator, it is therefore negative teaching.

Of course, G forces cannot be reproduced in an airliner simulator. But the flight instrument indications of a Jet Upset are easily demonstrated. An inverted nose low attitude will reproduce quite normally on the ADI and the airspeed and altimeter readings work also as expected. I have observed this many times in a Boeing 737 Classic simulator. Recovery action follows the recommendations in the FCTM.

While the comments in the Airbus Memo (which I have not seen, but only heard about) may well apply to fly by wire types, it seems to me Airbus have their head in the sand if they think the comments apply to other types.
Perhaps Airbus pilots who have read the Memo from the manufacturer would care to comment

Microburst2002
18th Apr 2010, 16:46
Haven't read it.

From your report of it, it seems that Airbus thinks it is not advisable to practice upset recovery in sims because they can't be properly simulated.

It is like practicing a looping with a 747 in the sim. The sim cannot simulate it. It can only "extrapolate". And the feeling cannot be reproduced, of course.

However, in many upsets in IMC body feelings are misleading so you can well use a simulator to practice instrument flying out of the upset using the displayed information only, regardless of what the seat of the pants says.

It is good to know that too steep a pitch down attitude with speed rapidly increasing requires you to first level the wings and then pull the nose, but it is better to practice that manoeuvre and see the difference. And by the way, what to do with thrust, and when? I recall a joint Airbus-Boeing memo on upsets, but in this regard, it left it to each model depending on where the engines are mounted.

lomapaseo
18th Apr 2010, 17:01
It is good to know that too steep a pitch down attitude with speed rapidly increasing requires you to first level the wings and then pull the nose

admittedly I don't understand, as a non pilot, but what is meant by leveling the wings when you are in a significant nose down attitude:confused:

What kind of pitch are we talking about in an upset? 10, 50 or 90 deg?

Tmbstory
18th Apr 2010, 19:28
Centaurus and Microburst:

It is a pity that Airbus cannot see the "woods for the trees". I am sure that they could contribute if they wished to and somethig would be better than nothing.

Regarding the point about thrust, it helped in our recovery by assisting in getting the nose to fall and also in the recovery, by helping the nose to rise.

Tmb

Air Tourer
19th Apr 2010, 05:11
Mm. Centaurus mentions "INVERTED nose-low attitude", and that's the last I read of it. And yet some accident reports are of airliners in unusual attitudes and pilots seemingly making things worse.
Don't know about airliners, but in the above situation, pulling controls back is going to get you into a very fast dive.

Microburst's example, "level wings, pull the nose" would be if not inverted.

Laomapseo, wings level first in this regard is to get them horizontal while yet still in the pitch down position, THEN pull up. (gently)
Otherwise, with a high angle of bank, as in a recient indonesian crash,
the up elevator will be pulling the a/c around into a spiral dive, as at 90deg angle of bank it would work as a rudder.

Airline pilots could do all this in light aircraft, but some of the accidents started with the pilots not reconizing which way was up.

vapilot2004
19th Apr 2010, 06:29
I have been told that the Airbus rationale is many an unusual attitude is beyond the capability of the sim for the simple reason that it is outside programmed parameters and protections integrated into the fly by wire system.

This is not to say that the Airbus will fail where a non-Airbus type FBW or conventionally controlled aircraft will succeed here. It is just that the UA recovery situation is contrived in the first place and there is no amount of programming that could recreate such a recovery with reasonable fidelity.

galaxy flyer
19th Apr 2010, 07:15
My current mob goes to NTPS in Mojave every three years for upset training in a Impala, a poorly powered military trainer. Stall, spins, and recoveries from all angles. I found it a useful refresher, but nothing new as I have 1200 hours of tac fighter time.

But, nothing in the sim will be equal to 45 minutes in a real plane, inverted.

GF

Microburst2002
19th Apr 2010, 08:27
If I ever find myself in inverted flight in the airbus, I am not confident that I will be able to recover, as I have never had any aerobatics training, even theoretical. My instincts can kill me due to the lack of training.

Airbus FBW logic has accounted for upsets. There is an abnormal attitude flight control law.

Anyway, Where is the airbus memo, bulletin or "getting to grips with" where I can learn what to do in the different upsets we could find ourselves one day?

I would love to do that training in the Mojave desert, but I am afraid no airline will not sponsor me...:{

rudderrudderrat
19th Apr 2010, 10:16
Hi,

The only information I can find on this is:
here (http://www.ntsb.gov/events/2001/AA587/exhibits/240005.pdf)
Is there something else?

Pugachev Cobra
19th Apr 2010, 11:13
When I first heard that big simulators used only pre-computed values, I got a little concerned. Why would top of the line world class simulators training airline pilots still use this old method only?

Maybe it's because it's the same model when the first sims were made, when it wasn't possible for real time calculations?

But nowadays is a different story.

There are models, most notably Blade Element Theory, that with a simple basic home computer, could compute many times per second the vectors of the forces in various parts of the aircraft.

So it is possible to simulate upset recoveries. Maybe it won't be perfectly accurate, but it will give good guidelines on how the aircraft would react.

If it's a certification problem with the old aviation industry rationale "if it's working, don't mess with it", we could use pre-computed values for normal attitudes, and change to real time flight models with unusual attitudes.

Technically is really simple.

I still get amazed on how the aviation industry walks 30 years behind the rest of the world when it comes to using new technology that we see on everyday use. FANS/CPDLC comes to mind.

Mad (Flt) Scientist
19th Apr 2010, 18:56
When I first heard that big simulators used only pre-computed values, I got a little concerned. Why would top of the line world class simulators training airline pilots still use this old method only?

Maybe it's because it's the same model when the first sims were made, when it wasn't possible for real time calculations?

But nowadays is a different story.

There are models, most notably Blade Element Theory, that with a simple basic home computer, could compute many times per second the vectors of the forces in various parts of the aircraft.

So it is possible to simulate upset recoveries. Maybe it won't be perfectly accurate, but it will give good guidelines on how the aircraft would react.

If it's a certification problem with the old aviation industry rationale "if it's working, don't mess with it", we could use pre-computed values for normal attitudes, and change to real time flight models with unusual attitudes.

Technically is really simple.

I still get amazed on how the aviation industry walks 30 years behind the rest of the world when it comes to using new technology that we see on everyday use. FANS/CPDLC comes to mind.

Simply put, I would trust a flight-matched model, using empirical data, over some theoretical model any day of the week. The idea of using something like blade element theory to model post-stall behaviour of an airliner is ridiculous, frankly.

All the OEMs use CFD - and real, Navier-Stokes, versions, not simplified approximations - during design. But we also use wind tunnel testing - and a lot of it, and its bloody expensive - because, frankly, even full NS isnt up to the job sometimes. And then we go and test - extensively - the real thing, because again there's no substitute for reality.

I've seen CFD and wind tunnel data be a LONG way off reality - several degrees of error in the onset of a stall, for example, or tens of percentage points in a stability derivative. Empirical data is still the way to go.

Pugilistic Animus
19th Apr 2010, 20:38
Pay some guy/gal to take you up in a T-38, L-39 or F5 ,...then you can really do jet upsets:)


. Empirical data is still the way to go.

you don't say :D

Rick777
20th Apr 2010, 05:22
I have done upset training in the A320 as well as most of the Boeings. I am also ex-USAF and have flown upside down a few times. Except for the lack of G-force and things flying around the Boeings fly pretty well doing aileron rolls etc. The A320 sim does not it is very jerky and not like an airplane when you get to extreme attitudes.

PBY
20th Apr 2010, 05:44
I had a great instructor the other day in England. He was an ex Boeing guy. He broke the taboo and let me do some barrel roles, loopes, flying upside down and some unusuall attitude recoveries in an A320 sim. Even though it might not be politically correct according to the Airbus, I think it did not hurt my scanning ability nor my situational awareness. The history of Airbus thinkers seem to be more reactive than proactive. But I feel much better after this session. You learn to use the skypointer in those situations.
I am just saying, that some more training in the sim never hurts. I guess we are intelligent enough to understand, that simulator is not an airplane, but it can teach us not to pull through when nose down and on our back.

Pugachev Cobra
21st Apr 2010, 22:51
Simply put, I would trust a flight-matched model, using empirical data, over some theoretical model any day of the week. The idea of using something like blade element theory to model post-stall behaviour of an airliner is ridiculous, frankly.

All the OEMs use CFD - and real, Navier-Stokes, versions, not simplified approximations - during design. But we also use wind tunnel testing - and a lot of it, and its bloody expensive - because, frankly, even full NS isnt up to the job sometimes. And then we go and test - extensively - the real thing, because again there's no substitute for reality.

I've seen CFD and wind tunnel data be a LONG way off reality - several degrees of error in the onset of a stall, for example, or tens of percentage points in a stability derivative. Empirical data is still the way to go.Mad Scientist, it's good to have input from someone who's obviously an insider in the field.

I reckon it will be most certainly never fully possible to have 100% accurate CFD's.

Actually I wasn't aware that studies of comparison between CFD's and a flight-matched model were being done, and that CFD's were several degrees off as you put it.

The scientific principle of what applies locally, also applies broadly (sorry the name of the principle has slipped my mind) should be used.

Still, all I think is that the approach the industry is having, "don't fly on that regime, just do as we tell you, you don't need to experience it" because of a gapping hole in our knowledge - I assume we don't have out of the envelope pre-computed values because of too many variables - isn't a good excuse for not finding a way to train flight crews in every situation possible, to expect the unexpected.

That's my 2 cents, and thank you again for your insight.