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New (2010) Stall Recovery's @ high altitudes

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New (2010) Stall Recovery's @ high altitudes

Old 29th Jul 2010, 20:48
  #101 (permalink)  
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Originally Posted by john_tullamarine
Hence, for all Type specific discussions going beyond a bit of a yarn on PPRuNe, one MUST

(a) check the TCDS for the relevant frozen Design Standard revision(s) applicable to the particular certification

(b) refer to that/those (generally now superseded) documents rather than the current words
Yes, indeed!

In fact, I'm dealing with such issues this very week.

PBL
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Old 29th Jul 2010, 21:59
  #102 (permalink)  
 
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One of the problems in this matter has been the poor wording in Manuals and similarly, yet different, the view taken by the FAA – three views at least, certification, regulatory, and training/checking.
If the objective is to train to the approach to the stall, as may have been the case, then this requires specific aspects of awareness and flight techniques.
With more recent focus on Loss of Control, then training has been diverted to ‘upset recovery’ vice a stalled aircraft. This training is very context dependent.
Only now is stall training being considered again in detail, and this too depends on context and may require specific awareness and ‘aircraft type dependent’ techniques.

Attempting to unravel poor descriptions, undo weak training practices, and simultaneously introduce new programs will be fraught with problems – thus we have arrived.

As much as BOAC might not like certification regulations , a good understanding of these will aid training requirements and an understanding of manufacturers’ recommendations.
Although the requirements in CS25 / FAR25 etc, might not be in accord with academic theory, they are the basis on which particular aircraft have been judged – what aircraft do in practice and not what they should do in the classroom.

Of the commercial types which I was associated with, the stall evaluation was extensive. It progressed well beyond any training stall or concept of an upset manoeuvre, in search of the academic T tail deep stall (wind tunnel predicted), but which as far as we know, is not encountered – (from Vss, hard stick back, 5 deg/sec pitch rate, resulting in at least 5 deg stall alpha over-swing).
Turning stalls did induce a wing drop, for which lateral control can be used to aid recovery (as per CS25), but this may not be generic advice as control response in such conditions will be type dependent.
It’s nice to ensure that the inner wing stalls before the tip and thus enable conventional ailerons to be used.

Of course things don’t always go as planned. With development and increasing weight the stalls became more variable with a notable roll off. Extensive aerodynamic instrumentation failed to disclose a reason and the wt/cg certification was limited by the maximum roll angle with use of full control (aileron and rudder) in the stall.
Subsequently, slight wing twist at high weight has been identified as the likely problem.
None of the above would be of direct relevance to a training program, except perhaps a better understanding of why this manufacturer in this particular aircraft type includes the use the aileron or rudder control as required to control roll angle during a stall recovery.

IMHO the issue which the regulators (training) should be looking at is why aircraft are deviating from safe flight into the speed/manoeuvre safety buffer prior to stall warning and an actual stall; what’s generating these problems.
Also, as noted by BOAC, understand trim; there are some significant differences both in theory and application amongst modern aircraft types.
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Old 29th Jul 2010, 22:34
  #103 (permalink)  
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three views at least, certification, regulatory, and training/checking

And that's been a sticking point for years probably in just about every Contracting State.

The training paradigm traditionally has been about minimum loss of height without regard to how the design, certification and FT processes intermesh. The need for a reduction in alpha to get away from the main stalling problem as a first action appears never to have got into the training regime's thought processes and that has been the main safety disconnect in the whole thing ....

(stands by for JF to wade in with technical TP stuff ...)
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Old 30th Jul 2010, 07:38
  #104 (permalink)  
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SP - noted. I have absolutely nothing against the certification requirements - there has to be a base-line, be it right or in need of 'tweaking', against which a/c can be judged. My comments on this thread against the 'theoreticians'/certificators' has been that we are seeing more and more near or complete LOC at excessive pitch angles which arrive at FULLY stalled a/c.

I know from airtests that you cannot properly 'stall' a 737 in line with the airtest schedule- there is no more 'up elevator' available to stall the wing and we settle for declaring a benign gentle nose drop as the 'point of stall' when in fact it represents the limit of pitch control, so the 1g clean stall really has merit only in checking that the stall warning functions correctly and that there are no adverse excursions in roll, yaw or pitch NEAR the stall. The actual airtest stall has no relevance to the situations in which crews seem to be finding (?placing?) themselves.

Unfortunately the 'training system' has followed this philosophy and in my view, as I have often said, we need to thoroughly overhaul the training system for the glass cockpit and I completely endorse SP's last paragraph. Wittingly or unwittingly we have allowed ourselves to be 'automated' into a world where 'it can't happen'. Wandering only slightly off topic, PJ2's post on the TIP crash says "It is just an airplane, and it requires flying skill; it is not a platform which requires mere "managing" and this is where I see the whole system failing - it encourages crew to 'manage' a complex and clever system and seems to forget the fact that when you press a few big red buttons the a/c and crew SHOULD be capable of just flying the a/c. The very point of my thread on the Safety Forum on the 'Computers in the cockpit etc'.
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Old 30th Jul 2010, 16:17
  #105 (permalink)  
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Originally Posted by BOAC
My comments on this thread against the 'theoreticians'/certificators' has been that we are seeing more and more near or complete LOC at excessive pitch angles which arrive at FULLY stalled a/c.
One of the difficulties with making comments "against" specific people is that what starts out as a legitimate difference in emphasis can turn into an artificial polarity, and I would rather not see this happen in this case because this is a complex set of issues with plenty of potential for confusion.

That said, I would like to address, first, the issue of whether "we are seeing more and more near or complete LOC...", and, second, whether it is possible to train for it, or whether there is no practical alternative to training for avoidance.

This morning, for lack of anything better to do after having read DO-178A a few times and commented on it to others, I went into Flight International's annual safety reviews for 2007, 2008, 2009, to identify LOC with stalls. I just looked at fatal accidents with scheduled passenger flights, non-scheduled passenger flights, freight flights, and regional/commuter flights (FI's categories).

Let's look at the commercial large aircraft stuff first. If it's OK, I won't count Antonov 12's because there are a lot, but I will count the other Antonov's.

2007: Total:11

Passenger:
01.01 Adam Air, B737, Indonesia, Departure from cruise flight
09.01 Aeriantur, An-26B, Iraq, Crashed on Approach
07.03 Garuda, B737, Yogyakarta, Runway overrun
17.03, UTAir, Tu134A, Samara, Landed short
05.05 Kenya, B737, Cameroon, Descent into terrain after TO
28.06 Angola, B737, Angola, Landing accident
17.07 TAM, A320, Sao Paolo, Runway overrun

Non-passenger:
23.07 Djibouti, An-26, Ethiopia, Engine failure on climb out
26.08 Great Lake Business, An-32, Congo, Engine failure on climb out
20.09 Arctic Circle Air, Shorts Skyvan, Mystic Lake, Alaska, failed to climb on ferry flight after damage
04.10 El Sam, An-26, Congo, Engine failure after TO

2008: Total:10

Scheduled Passenger
15.04, DC-9, Congo, Runway overrun
30.05 TCAC A320, Tegucigalpa, Runway overrun
10.06 A310, Sudan, fire after landing
20.08 Spanair, Madrid, TO accident
24.08 Itek B737, Bishkek, Approach to Landing
14.09 Aeroflot Nord, B737, Perm, Approach to Landing

Non-passenger
30.06, Ababeel, Il-76, Sudan, Crashed after TO, perhaps engine fire
06.07 USA Jet Airlines, DC-9, Saltillo, Mexico, "crashed on a road 800m from airport". Not said whether TO or landing
30.08 Conviasa, B737, Ecuador, CFIT
27.11 XL Airways, A320, Perpignan, LOC during acceptance testing

2009: Total:14

Scheduled Passenger
25.02 Turkish, B737, Amsterdam, Approach to Landing
12.02 Colgan, Q400, Approach to Landing
09.04, Aviastar Mandiri, BA146, Indonesia, CFIT on approach to landing
01.06 Air France, A330, Departure from Cruise Flight
30.06 Yemenia, A310, near Moroni, Approach to Landing
15.07, Caspian, Tu 154M, Departure from Cruise Flight
24.07, Aria, Il-62M, Runway overrun
04.08 Bangkok, ATR-72, Thailand, Lost control after landing

A Q400 counts as a large commercial for my purposes here.

Non-passenger
09.03 Aerolift, Il-76, Entebbe, Crashed on TO
23.03 FedEx, MD-11 Tokyo, LOC on landing
26.05 Service Air, An-26, Congo, Approach to Landing (short final)
21.09, Sudan Airways, Boeing 707, Sharjah, crash after TO
01.11 Russian Interior Ministry, Il-76, apparent LOC on TO
28.11 Avient, MD-11, Shanghai, LOC after tailstrike on TO

2010:

It's a week too early for David's list, so let me guess

25.01 Ethiopian, B737, nr Beirut, Departure from Climbout after TO
12.05 Afriqiyah, A330, Tripoli, Approach to Landing
22.05 Air India Express, B737, Mangalore, Runway overrun
28.07 AirBlue, A321, Islamabad, Approach to Landing

Now, which of these involved full stalls at high AoA whose recovery would have avoided the accident?

2007: Adam Air? Questionable: they had lost control before this because they weren't paying attention to flying the airplane
Ariantur? Who knows?
Kenya? There were other things wrong

2008: Spanair? Hardly; better to have your high-lift devices out
Bishkek? Who knows?
Perm? The MAK said otherwise
XL Airways

2009: Turkish. The report said that there was no altitude for stall recovery. There was lots wrong with their handling before the AC stalled
Yemenia? Who knows?
Colgan. The aircraft was stalled from controlled flight by the PF's actions.

So I will go for XL Air and Colgan, and maybe Turkish. That's 3 out of 39. That doesn't seem like a rash of high-AoA-LOC accidents to me.

Now, there is nothing wrong with anticipating a trend and thinking of what to do about it. But to me the trend is not yet clear.

Now, what to do about it? Train for high-AoA-LOC recoveries? Well, I don't think that's feasible, but what do I know, I don't fly these big high-performance airplanes. But I do talk to and work with people who have designed and analysed them.

I don't think it is feasible because what an airplane does in these regimes is highly specific and not really known. Real upsets are not flight-tested; this comes from wind tunnels. Simulators are no help, because outside the envelope there is no guarantee of veridicality. So, if you can't train for it, you can only train to avoid it. Here is the view of William Wainwright, Airbus Chief Test Pilot, in Issue 24 of FAST:
Originally Posted by Wainwright in FAST issue 24
We manufacturers were very concerned over the types of manoeuvres being flown in simulators and the conclusions that were being drawn from them. Simulators, like any computer system, are only as good as the data that goes into them. That means the data package that is given to the simulator manufacturer. And we test pilots do not deliberately lose control of our aircraft just to get data for the simulator. And even when that happens, one isolated incident does not provide much information because of the very complicated equations that govern dynamic manoeuvres involving non-linear aerodynamics and inertia effects. The complete data package includes a part that is drawn from actual flight tests, a part that uses wind tunnel data, and the rest which is pure extrapolation. It should be obvious that firm conclusions about aircraft behaviour can only be drawn from the parts of the flight envelope that are based on hard data. This in fact means being not far from the centre of the flight envelope; the part that is used in normal service. It does not cover the edges of the envelope. I should also add that most of the data actually collected in flight is from quasi-static manoeuvres. Thus, dynamic manoeuvring is not very well represented. In fact, a typical data package has flight test data for the areas described in Table 1. In other words, you have reasonable cover up to quite high sideslips and quite high angles of attack (AOA), but not at the same time. Furthermore, the matching between aircraft stalling tests and the simulator concentrates mainly on the longitudinal axis. This means that the simulator model is able to correctly reproduce the stalling speeds and the pitching behaviour, but fidelity is not ensured for rolling efficiency (based on a simplified model of wind tunnel data) or for possible asymmetric stalling of the wings. Also, the range for one engine inoperative is much less than the range for all engines operating and linear interpolation is assumed between low and high Mach numbers. Wind tunnel data goes further. For example, a typical data package would cover the areas described in table 2. In fact, this is a perfectly adequate coverage to conduct all normal training needs. But it is insufficient to evaluate recovery techniques from loss of control incidents. Whereas, the training managers were all in the habit of demonstrating the handling characteristics beyond the stall; often telling their trainees that the rudder is far more effective than aileron and induces less drag and has no vices! In short, they were developing handling techniques from simulators that were outside their guaranteed domain. Simulators can be used for upset training, but the training should be confined to the normal flight envelope. For example, training should stop at the stall warning. They are “ virtual” aircraft and they should not be used to develop techniques at the edges of the flight envelope. This is work for test pilots and flight test engineers using their knowledge gained from flight testing the “ real” aircraft.
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Old 30th Jul 2010, 20:53
  #106 (permalink)  
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You ignored the word 'near' in my post? An impressive list of irrelevant accidents. There have been several 'near' LOC in recent years which did not result in accidents - shall we ignore them?

Moving on:
Turkish:
"The report said that there was no altitude for stall recovery." Quite irrelevant to my point - should not have been there.
"There was lots wrong with their handling before the AC stalled" Totally relevant to my point. Likewise PGF, BOH, LHR, CPH, etc etc

"Train for high-AoA-LOC recoveries? Well, I don't think that's feasible, but what do I know, I don't fly these big high-performance airplanes. But I do talk to and work with people who have designed and analysed them." yes it is feasible (and done sometimes by those who understand) and you really should talk to the people who do fly them if you are to engage in this discussion on piloting.

"Real upsets are not flight-tested; this comes from wind tunnels." Unfortunately becoming untrue - quite a few pilots are inadvertently 'flight testing'

"So, if you can't train for it, you can only train to avoid it." Well, (1) you can - and (2) yes you must

WW:
"Whereas, the training managers were all in the habit of demonstrating the handling characteristics beyond the stall;" They obviously believed what the sim sales and design people told them?

"often telling their trainees that the rudder is far more effective than aileron and induces less drag" Correct on the real thing. I know not in the sim. The only roll control you have in the real aircraft and if correctly applied it works and is NOT dangerous as some seem to think. Wrongly used = big vices.

Lastly I am watching a trend, not anticipating one. Do your analytic programmes allow you to factor in reduced training, experience, increasing subservience to automation, less 'piloting' and rest to accident prevention?

The big 'poke you in your eyes'/'kick you in the balls' message right now is TRIM
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Old 30th Jul 2010, 21:34
  #107 (permalink)  
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BOAC,

I took your proposal seriously enough to spend a number of hours today trying to figure out if it was true or not. I thought the results I obtained were worth broadcasting, as a contribution to discussion. I'm sure they are not the end of the story.

I can't at present join the dots in your argument that people have to be trained to recover upsets in large commercial airplanes. I just can't see how that can realistically be done. Neither, apparently, can Airbus's main man. If you have a proposal, please do bring it up for discussion.

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Old 30th Jul 2010, 22:26
  #108 (permalink)  
 
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Originally Posted by PBL View Post
BOAC,

I can't at present join the dots in your argument that people have to be trained to recover upsets in large commercial airplanes. I just can't see how that can realistically be done. Neither, apparently, can Airbus's main man. If you have a proposal, please do bring it up for discussion.

PBL
Quite simple actually. The training would be done in groundschool.
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Old 31st Jul 2010, 07:46
  #109 (permalink)  
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Originally Posted by boac/#93?
it is apparent, to me anyway, that 'stall' recoveries MUST now lead straight into the nose-high low-speed recoveries as an exercise, meaning that I would suggest allowing trimming right down to stick shake. Recovery from these conditions is indeed simple if you are prepared for it and take the correct actions.
Yes, groundschool to introduce the topic - excellent idea - but in the sim it is so easy. None of the 'unusual positions' I flew a few years back on a Boeing triggered sim exercise were done 'out-of-trim' but could have been. Better to see the a/c stand on its tail in a box 8 ft off the ground that can be 'frozen' than in an a/c 800ft up that cannot.
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Old 31st Jul 2010, 08:47
  #110 (permalink)  
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OK, BOAC, you are concerned about the specific condition in which a pilot executing a vertical escape manoeuvre of some sort is unaware of the position of the longitudinal trim. There are two ways in which heshe could be unaware, namely (a) it is displayed and available, but not noticed, or (b) the position is not displayed in a readily-assimilable manner during the manoeuvre.

Situation (a) is what I call an attention failure (the "A" in the PARDIA flow-of-information classification). Situation (b) is a violation of what I call the Mutual Cognition of Relevant Parameters (MCRP) Criterion in my IET System Safety Keynote last year (Securing the Interface; I just noticed that we failed to put a copy on the WWW. I'll remedy that later). I think you are concerned about both situations, but I feel it appropriate to distinguish them.

You suggest it's a trend. It may be, or it may not be, I can't tell. What would be very helpful is to have a definitive list of situations in which (b) has occurred. I listed fatal accidents in the last four years in my post yesterday; maybe, if you have the time and motivation, you could write a definitive list of those incidents in which situation (b) has occurred and has arguably adversely affected the safety of flight. I think from my list only Turkish and XL Airways fit (there may be some speculation concerning others).

This is not an old concern. It arose during the Nagoya accident to a China Air Lines A300 in 1994. The report also identified other upsets (over Paris; over Moscow) in which automated trimming of the THS had led to pitch-ups and high-AoA situations in this line of aircraft (A300/310).

I advised counsel for the plaintiffs in the civil proceedings concerning the Nagoya accident in 1998 (the trial was in 1999, I believe). They didn't use my advice in court AFAIK, but what I advised them was identical with what the court finally found.

You point out, though, that it is not only Airbus aircraft which engender situation (b). Which other aircraft are subject to it?

PBL
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Old 31st Jul 2010, 10:14
  #111 (permalink)  
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Well, I have the time but after your second paragraph I'm fresh out of motivation
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Old 31st Jul 2010, 10:29
  #112 (permalink)  
 
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2009: Turkish. The report said that there was no altitude for stall recovery. There was lots wrong with their handling before the AC stalled
Not quite sure about your assessment on that accident. From what I read of the accident the thrust levers closed because of a fault in the radio altimeter and the crew simply watched it happen. They had plenty of altitude to recover when the airspeed was already approaching the stall but were obviously nonplussed and took no action until too late. In the 737 simulator we have reproduced the sequence of events and at 300 ft above runway level at stick shaker with an awful lot of back trim already applied by the autopilot, a competent pilot could recover providing he got on to the problem promptly and was not afraid to use significant stabiliser trim to aid elevator control.
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Old 31st Jul 2010, 10:52
  #113 (permalink)  
 
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While you guys are duking it out over whether a trend exists with regard to stall accidents, I thought I'd just point out that at the rather large joint conference in Toronto next week, AIAA will host three sessions which may be enlightening. I've taken the liberty of posting the agendas for these sessions below. I would suggest that the existence of these sessions, and the amount of effort that has gone into the development of the papers to be presented, rather strongly supports BOAC's notion that a) this is a problem, and b) a lot can be done about it.

I'll be there, but I'm funded. Anyone else?



Aircraft Loss of Control I: The Problem and Technical Challenges:

2:00 PM-2:30 PM

AIAA-2010-8002. Loss of Control – Avoidance, Recognition and Recovery: Reducing the Leading Cause of Accidents J. M. Cox
2:30 PM-3:00 PM

AIAA-2010-8003. Accident Lessons for Stall Upset Recovery Training D. A. Crider
3:00 PM-3:30 PM

AIAA-2010-8004. Aircraft Loss-of-Control Accident and Incident Analysis C. M. Belcastro
3:30 PM-4:00 PM

AIAA-2010-8005. Loss-of-Control: Perspectives on Flight Dynamics and Control of Impaired Aircraft H. G. Kwatny; J. Dongmo; R. Allen; B. Chang; G. Bajpai No itinerary selected
4:00 PM-4:30 PM

AIAA-2010-8006. Human Factors of Aircraft Loss of Control Accidents S. Casner No itinerary selected
4:30 PM-5:00 PM

AIAA-2010-8007. Aircraft Loss of Control Causal Factors and Technical Challenges S. R. Jacobson
5:00 PM-5:30 PM

AIAA-2010-8008. Technical Challenges of Upset Recovery Training: Simulating the Element of Surprise J. S. Burki-Cohen
5:30 PM-6:00 PM

AIAA-2010-8009. Results of a Comprehensive In-Flight Simulation-Based Advanced Maneuver & Upset Recovery Training Study J. Priest


Aircraft Loss of Control II: Potential System Solutions

9:00 AM-9:30 AM

AIAA-2010-8139. Some Thoughts on Reducing the Risk of Aircraft Loss of Control D. Bateman
9:30 AM-10:00 AM

AIAA-2010-8140. Examination of Icing Induced Loss of Control and its Mitigations A. L. Reehorst; H. E. Addy; R. O. Colantonio
10:00 AM-10:30 AM

AIAA-2010-8141. Development and Implementation of a Model-Driven Envelope Protection System for In-Flight Ice Contamination D. R. Gingras; B. Barnhart; R. Ranaudo
10:30 AM-11:00 AM

AIAA-2010-8142. Future Concepts for Preventing Aircraft Loss-of-Control Accidents C. M. Belcastro; S. R. Jacobson
11:00 AM-11:30 AM

AIAA-2010-8143. Validation and Verification of Future Integrated Safety-Critical Systems Operating Under Off-Nominal Conditions C. M. Belcastro


Aircraft Loss of Control III: Upset Simulation and Training

2:00 PM-2:30 PM

AIAA-2010-7791. What Really Can Be Done in Simulation to Improve Upset Training? S. K. Advani; J. A. Schroeder; B. Burks
2:30 PM-3:00 PM

AIAA-2010-7792. Simulation Modeling for Off-Nominal Conditions - Where Are We Today? G. H. Shah; J. V. Foster; K. Cunningham
3:00 PM-3:30 PM

AIAA-2010-7793. Improvement of Stall-Regime Aerodynamics Modeling for Aircraft Training Simulations D. R. Gingras; J. N. Ralston
3:30 PM-4:00 PM

AIAA-2010-7794. Developing Scenarios for Research into Upset Recovery Simulation L. ****e; M. Grigorev; V. Biryukov; E. Groen
4:00 PM-4:30 PM

AIAA-2010-7795. Approach to Stall Training in Simulators D. Carbaugh
4:30 PM-5:00 PM

AIAA-2010-7796. Training to Prevent Upset J. Drappier
5:00 PM-5:30 PM

AIAA-2010-7797. Ground Based Simulation of Airplane Upset Recovery Using an Enhanced Aircraft Model F. Liu ; P. R. Grant
5:30 PM-6:00 PM

AIAA-2010-7798. Effectiveness of Sustained G Simulation in Loss of Control and Upset Recovery Training S. Glaser; P. Comtois

AIAA-2010-8141. Development and Implementation of a Model-Driven Envelope Protection System for In-Flight Ice Contamination D. R. Gingras; B. Barnhart; R. Ranaudo
10:30 AM-11:00 AM

AIAA-2010-8142. Future Concepts for Preventing Aircraft Loss-of-Control Accidents C. M. Belcastro; S. R. Jacobson
11:00 AM-11:30 AM

AIAA-2010-8143. Validation and Verification of Future Integrated Safety-Critical Systems Operating Under Off-Nominal Conditions C. M. Belcastro
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Old 31st Jul 2010, 11:05
  #114 (permalink)  
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Mansfield - excellent news. Thank you. I did not know about this.
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Old 31st Jul 2010, 18:33
  #115 (permalink)  
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Centaurus,

Originally Posted by Centaurus
Not quite sure about your assessment on that accident.
I said:
Originally Posted by PBL
2009: Turkish. The report said that there was no altitude for stall recovery. There was lots wrong with their handling before the AC stalled
Let me rephrase. The report said on pp 6-7 that when the aircraft stalled "the height remaining ... was insufficient for a recovery". There was lots wrong with their handling before the AC stalled. There were also other things wrong which did not concern their handling. Better?

Mansfield,

I didn't think we were talking about LOC accidents in general. As far as I can tell, BOAC is mainly concerned, not about LOC accidents in general, but about a specific kind of LOC accident. But if we are, then of the list I gave, many are LOC accidents. Let me specifically indicate those I think are LOC, although there is room for quibbling:

2007:
01.01 Adam Air, B737, Indonesia, Departure from cruise flight
09.01 Aeriantur, An-26B, Iraq, Crashed on Approach
05.05 Kenya, B737, Cameroon, Descent into terrain after TO
23.07 Djibouti, An-26, Ethiopia, Engine failure on climb out

2008:

20.08 Spanair, Madrid, TO accident
24.08 Itek B737, Bishkek, Approach to Landing
14.09 Aeroflot Nord, B737, Perm, Approach to Landing
30.06, Ababeel, Il-76, Sudan, Crashed after TO, perhaps engine fire
06.07 USA Jet Airlines, DC-9, Saltillo, Mexico, "crashed on a road 800m from airport". Not said whether TO or landing
27.11 XL Airways, A320, Perpignan, LOC during acceptance testing

2009:

Scheduled Passenger
25.02 Turkish, B737, Amsterdam, Approach to Landing
12.02 Colgan, Q400, Approach to Landing
01.06 Air France, A330, Departure from Cruise Flight
30.06 Yemenia, A310, near Moroni, Approach to Landing
15.07, Caspian, Tu 154M, Departure from Cruise Flight
04.08 Bangkok, ATR-72, Thailand, Lost control after landing
09.03 Aerolift, Il-76, Entebbe, Crashed on TO
23.03 FedEx, MD-11 Tokyo, LOC on landing
26.05 Service Air, An-26, Congo, Approach to Landing (short final)
21.09, Sudan Airways, Boeing 707, Sharjah, crash after TO
01.11 Russian Interior Ministry, Il-76, apparent LOC on TO
28.11 Avient, MD-11, Shanghai, LOC after tailstrike on TO

2010:

25.01 Ethiopian, B737, nr Beirut, Departure from Climbout after TO
12.05 Afriqiyah, A330, Tripoli, Approach to Landing

That is 24 from 39. Over half and just under 2/3 of all fatal accidents to large commercial aircraft in the period. Even if I take out those about which I am unsure, there are still 18 sure LOCs, just under 1/2. It is widely agreed that LOC has taken over from CFIT as being the largest fatal-accident category. It is also an issue for the military. NASA has been working on LOC for a while, I understand, but I didn't know Don Bateman was working on it also.

BOAC has stressed, if I understand him right, that he is most interested in high-AoA departures which involve automatic trim movement not necessarily clearly annunciated to the pilot. As I said earlier, that appears to be 2 or 3 of those 39.

BOAC,

Originally Posted by BOAC
I have the time but after your second paragraph I'm fresh out of motivation
Pity.

PBL
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Old 31st Jul 2010, 19:11
  #116 (permalink)  
 
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I said this before: the stall is the most dangerous thing in aviation,...and at the same time it really is not

my final answer
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Old 31st Jul 2010, 19:25
  #117 (permalink)  
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Originally Posted by PBL
As far as I can tell, BOAC is mainly concerned, not about LOC accidents in general, but about a specific kind of LOC accident.
- yes! Posted in #63 and for those who slept through it again in #93. This thread is where theory and practice part company and why my 'motivation' is 'diverging on the negative axis' (=getting less).

'Control' to those who operate these machines simply means flying from A to B and touching down at B in such a way as to not puncture any lips or break teeth. Failing to achieve that at B is generally a 'loss of control' somewhere along the line, be it through sabotage, incompetence, structural failure, CFIT or whatever. All your list qualify. However, my particular concern now has been focussed here on the pitch problem.

'Mansfield's conference' would appear to be in accord. Perhaps try to get a transcript of the second event (3pm) on day 1 and that at 5:30pm and the next. Then have a day off and pick it up at 2:30 on day 3 and stay with it.

Mansfield - If there is any link to a summary afterwards I would be grateful.
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Old 2nd Aug 2010, 15:42
  #118 (permalink)  
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IGH - my initial 'simple' solution (which will not suit all, I know.........) is based on the fact that we need to retain the ability to trim ALL stages of flight, including very low speed, but that we should have:-
a) A warning that we have gone past 'sensible' with a possible 'stop'
b) A requirement to actively over-ride the stop when needed.

It appears to be the 'un-noticed' extreme trim position that is causing the problem, so let's 'notice' it, loud and clear and obviously?

This is not a big technological challenge.
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Old 2nd Aug 2010, 18:24
  #119 (permalink)  
 
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And, to reinforce PBL's point, while that Boeing diagram may be principally thinking about Mach effect from, say, ).5 through to 0.8, there are aerofoils where the Mach effect is perceptible all the way down to very low numbers - 0.2 or lower - a speed regime where Mach effects are not normally expected.
(p-pinfinity)/(1/2rhoV^2)/Cpi=1/[1-M^2]^.5+ [M^2/1+{1-M^2}^.5]*(cpi/2)

or maybe just 1/[1-M^2]^.5

no further comments


Last edited by Pugilistic Animus; 3rd Aug 2010 at 23:11. Reason: division symbol in red
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Old 4th Aug 2010, 16:18
  #120 (permalink)  
 
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Originally Posted by Pugilistic Animus View Post
(p-pinfinity)/(1/2rhoV^2)/Cpi=1/[1-M^2]^.5+ [M^2/1+{1-M^2}^.5]*(cpi/2)

or maybe just 1/[1-M^2]^.5

no further comments

Actually, no, mot just the "standard" Mach effect. Stall AOA ends up being a powerful function of freestream Mach, due to transonic effects in the (very accelerated) boundary layer. As a result the freestream Mach is not the Mach directly having the effect.

What you're alluding to is fine at more 'normal' AOAs.
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