Minimum Altitude Loss in Stall Recovery

[Mansfield]

We've been having this discussion in the States since a couple of days after the Roselawn accident, if not longer. It seems to come up again and again, which would seem to support John Ralston Saul's contention that one of the most important features of technocratic management is the extinguishment of memory. In any event, the FAA put this SAFO out this morning, and I thought it might be of interest. Regardless of whether you operate in the FAA world or not, this could generate some good discussion within your training departments.

http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2010/SAFO10012.pdf

[Mansfield]

There is no specificity in the SAFO which restricts it to high altitude operations.

With respect to stalls which may occur prematurely due to ice contamination, we typically see a nose up control input immediately following the pitch down generated by the stall. Some of this may be due to the flight crew failing to identify the stall. This, in turn, may be because a stall due to ice contamination can take place well before artificial stall warning and may generate wing pressure distributions that result in unique, often violent aircraft behavior not previously experienced in clean stalls.

At Roselawn, the DFDR data shows an attempt to raise the nose back to a more normal attitude from the pitch down attitude following the first roll event. This attempt raised the nose back above the angle of attack which happened to be critical at that moment due to the existing ice contamination. The resulting second roll inverted the airplane; at this point, the crew had little chance of recovery. Had they unloaded the wing and accelerated, managing the angle of attack carefully, they most likely would have recovered. Indeed, another ATR72 experienced a buffet while approaching South Bend a couple of hours following the Roselawn accident. That crew identified the ice accretion aft of the boots, and, from the comfort of an airplane still under control, made some very conservative decisions regarding configuration and speed which led to a normal descent into warmer air.

There is certainly a strong argument for procedures aimed at minimizing altitude loss close to the ground. Even then, retaining control of the airplane is obviously paramount. I recall the first accident that I ever investigated; this was a Fairchild Metro II at Washington Dulles. The captain had managed to flame out both engines due to ice ingestion during a night approach to runway 1R. As this occurred in final, he had little option but to execute a forced landing (other than mashing both start buttons, which we were pretty sure would have worked but which did not cross his mind at the time). He picked out a clear farm field and set up a power off approach into it. At some point he became aware that he was too slow and still high. I'd have to look in my notes, if I could figure out which box they were in, but he may have encountered the stall warning. At that point, he did something which I have always wondered whether I would have done. He shoved the stick forward, regained some margin above the stall, and immediately pulled back into a flare a couple of feet above the ground. The resulting landing left the airplane unsalvageable but the occupants essentially unhurt.

The argument that we have been trying to advocate for so many years is this: approaches to stalls are trained with a clean wing, in a steady deceleration, with a steady G, at an altitude well within the performance margins of the airplane. The aircraft behavior prior to and during this stall is entirely predictable and is so modeled by the simulator. Procedures for recovery which allow minimum altitude loss to overshadow the more important reduction in angle of attack lead to incorrect responses in nearly every type of stall situation other than the one demonstrated in the sim.

[Mach E Avelli]

Well, hooray for the FAA SAFO. My last FAA rating was done in the ERJ 145 simulator at a prominent training organization in the USA. Overall, the simulator training was excellent, with top quality instructors (well, all but one anyway). However, we wasted too much time perfecting the low level stalling exercises to a point that it could be said was negative training. Much emphasis was placed on minimal height loss (fair enough) but an equal amount of emphasis was placed on not gaining ANY altitude above the initial entry altitude during the recovery and pulling thrust back as soon as the nominated commencement speed was reached. The minimal height loss bit was fully understood, if the assumption was that in approach or landing configuration, and possibly turning, terrain would be just below. But a net height GAIN during recovery was, to my thinking, instinctive and desirable in such an assumed situation. Having got to stick shaker/pusher on approach, surely most pilots would be wanting to recover and continue climbing at high power to MSA while they called for a change of underwear? Given that if this occurs, all stabilized approach parameters have been shot to hell anyway, so continuing approach is hardly an option.
Of course high altitude recovery from stall requires a different technique, and to their credit, this was trained appropriately.
It would be great to see sim programs expanded to include stall recognition and recovery in severe icing, and the effects of asymmetric icing due system failures.

[A37575]

However, we wasted too much time perfecting the low level stalling exercises to a point that it could be said was negative training

Most of the stall recovery "training" I have experienced in the simulator is conducted around 15,000 ft in the landing configuration plus the occasional clean config. Seems to me a waste of time doing dirty stalls at such a high altitude and I wonder perhaps if this is a throw back from practicing stalling in the real aircraft.