Toronto AIAA Loss of Control Sessions
I just returned from three days in Toronto participating in the loss of control sessions at AIAA. There were about twenty-five presentations. Unfortunately there is no transcript, so-to-speak, as all presentations are based on published papers that AIAA sells.
Both Boeing and Airbus discussed the LOC issue, and they emphasized their collaboration and agreement on the fundamentals. The role of fully stalled airplanes in LOC was discussed extensively, and both manufacturers would like to see the “power-out” stall recovery eliminated. Rather, the recovery must incorporate a positive reduction in AoA before adding power. BOAC will be happy to know that the issue of the aircraft being fully trimmed just before the stall is well understood by all. Airbus pointed out that an aircraft trimmed nose up into the stall may not have enough elevator authority, with full power added, to lower the nose at all. Dave Carbaugh from Boeing pointed out that their general data, just like my icing specific data, shows a very common propensity to pull on the column when faced with stall or upset conditions. The Colgan captain was by no means the only guy to behave this way.
Both manufacturers stressed that large jet aircraft are laterally unstable while stalled, and the ailerons are most likely ineffective. However, before we slide down the slippery slope of rudder usage during stall recovery, I should point out that the manufacturers emphasize that before anything else, the wing must be unloaded, AoA reduced, flow reattached and then the ailerons will unroll the situation just fine.
Airbus also pointed out that there were almost no situations that require immediate action…there is usually a few seconds available to think it through before whomping on the controls. Their point was to get the response right before initiating action. Not unreasonably, they felt obligated to run wake turbulence up the flagpole, pointing out that this type of encounter would probably not require an immediate response.
There was also a lot of discussion about simulation, how to improve it, and the general inability of a typical hexapod simulator to get the job done.
As regards Don Bateman, he has a number of great ideas, and emphasized the need to do what can be done without hardware development. For example, he pointed out that a simple code change will allow the EGPWS to say, instead of “bank angle”, something like “roll left” or “roll right”. He would like to add an arrow in the middle of the ADI pointing the way to roll upright. He certainly sees the point regarding a low speed warning prior to shaker, and said that would be terribly easy to do. He is all set to display little colored trails behind the TCAS target in front of you; green for safely above the wake, yellow for getting close, red for too close to the wake, and it’s all corrected for the current wind. I really did enjoy his attitude; at the conclusion of his pitch, he simply said, “Any more questions?...Great, we know how to do this stuff, so let’s do it!”
This was contrasted with extensive discussions about systemic study and change embracing loss of control but including such things as adaptive control, envelope protection, damage assessment, etc., along with some of the busiest powerpoint slides I’ve ever seen (and I’ve seen a few in my day). I remarked to one of my NASA friends that the difference between Bateman and some of the PhD crowd was almost funny. Don would be down in your hellhole right now tweaking up the EGPWS, while everyone else is still looking for funding.
That said, there was a lot of good discussion and work presented, and I think it will ultimately yield a lot of change. Academic education in fundamental aerodynamics was stressed by a number of folks, as well as a revisit to the Upset Training Aid.