High Alpha?

February 17, 2010 by Bruce Landsberg

AOAThere’s been much consternation over the Colgan Airways Q-400(Dash8) accident in Buffalo last year that was basically the result of a stall. There are many circumstances leading up to that and we’ll have more to say in an upcoming issue of AOPA Pilot. Most CFIs who’ve  taught for any extended period get to understand the aerodynamics but a question is whether all of that knowledge gets passed along in a usable format. It is a mantra for students to regurgitate that an aircraft can stall at any airspeed but when angle of attack and distraction are high, that’s when things get really interesting.Too many are confused and unfortunately school is out by then. Gravity wins.

AOA or “Alpha” as the engineers call it, is one of the most important concepts for any pilot to really get. Too many of them don’t.  Perhaps the language used is also problematic. We say that the airspeed is slow instead of saying that the Alpha is high. In many cases the airspeed IS slow but might the language be creating a subconscious connection that it is airspeed and not angle that’s critical?

In the Colgan accident one of the revelations was a high level of distraction (there are many other revelations as well). Had the captain had a better concept of Alpha and a better appreciation for distraction, 50 people would be alive today. The real world of training and the real world are two different things. In training we strive to recreate reality but it is often contrived and the student catches us setting things up. Some CFIs also may not explain things thoroughly.

Essential AerodynamicsHere’s a shameless plug to ASF’s award winning online course on Essential Aerodynamics.  There’s video of a really accelerated stall,  a terrible density altitude accident and you’ll even get to do some surfing as we simplify Alpha to clarify it beyond any doubt. Even if you don’t need the review, perhaps there’s a new pilot or CFI who could benefit. It also qualifies for the FAA Wings program and the AOPA Accident Forgiveness and Deductible Waiver Enhancement program.

Let us know what you think.

Bruce Landsberg
Senior Safety Advisor, Air Safety Institute

ASI Online Safety Courses  |  ASI Safety Quiz  |  Support the AOPA Foundation

7 Responses to “High Alpha?”

  1. 1553 Says:

    Thanks Bruce, I’ve been searching quite some time for this info.

  2. Jim Bruchas Says:

    Bruce, It is interesting that this is not understood. As an Aero and Pilot, it was always obvious to me. Alpha/AOA is the difference between the Chord Line and the relative wind. There has to be Alpha to generate lift. This is caused by the pressure differential between the upper and lower surface. In the laminar flow steady state condition (Flying Alpha) all is well. In a stall or accelerated stall the upper surface flow separates into a turbulent (Low energy state) and the turbulent condition is a stall. Airlines don’t touch deep stalls or accelerated stalls, to risky. The simulator does not really duplicate it either. Letting George do all the flying in the weather in possible icing conditions and not paying attention caused this. It was not that the pilots did not recognize a stall, they weren’t even flying the aircraft. George did all he could but that was to maintain level flight whilwe increasing Alpha to a stall.

  3. Michael Dempsey Says:

    Bruce. AOA. or what ever you call it was just an event that was caused by the pilots having there heads up and locked. It may have been lack of training by the airline, But I think the mind set of the flight crew was not on the aircraft but every thing else. Maybe if the aircraft had a BIG red light and horn attached to the Stall warning and the AOA and the outside air temp. indicator. it would have helped. The mind set was not on flying the aircraft but going alone for the ride.

  4. Thomas Stegink Says:

    Have you considered the possibility the pilot thought he was in a tail-plane stall, due to icing and that he thought pulling back on the elevator was the only solution? I recall an FAA study a flying club friend linked us to that showed that the Roseville? Illinois stall (near Chicago) in the 90s was due to tail-plane icing, and that stall recovery is reversed under those conditions.

  5. Bill Hamilton Says:

    Bruce, Although a thorough understanding of angle of attack is essential to understanding the basics of flight, nothing screams louder than SITUATIONAL AWARENESS!! It doesn’t matter if your in a 777 trans atlantic or a Cherokee with Aunt Martha, one needs to stay aware of whats going on in and out of the plane. In most stall/spin training, the airplane is put into a very high pitch attitude until the break, and then to spin, rudder is added. This may lead the student to believe that if they never get close to this “extreme” attitude, they will never stall. We all know that is just not true. What happens if a bug clogs your pitot during flight and takes out your ASI? Does this mean were going to spin in?? Of course not, the relationship between pitch, power, sound, and feel of the controls should be well known. What is the sight picture on final at 80 knots? Where is the horizon & throttle? How do the controls react to inputs? This should be well recognized. What does an accelerated stall feel like? A turning stall at 50 degrees & what about recovery? Every time we slip to make that perfect landing in a crosswind we are cross controlled, but can we recognize that fatal cross controlled skidding turn from base to final?? The accident chain may be broken very early if the clues are recognized. Although angle of attack theory and understanding is all well & good, nothing can substitute the actual experience of different kinds of stalls or that one wing dropping for no “apparent reason” other than performing them at altitude with an instructor. Alpha will then be fully understood…

  6. Bruce Landsberg Says:

    Excellent comments – all. In a spring issue of AOPA Pilot, April I believe, you’ll see that we are in much agreement regarding the fact that the lights were on but nobody was home. As I said, this blog was a shameless plug for the Aerodynamics course.

    On Colgan — we could have a really long discussion.

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