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.
PBL