If you have been flying for more than a few years you probably believe most stall/spin accidents happen in the traffic pattern. And you are likely convinced that the base-to-final turn is the deadliest spot for stall accidents. And I don’t blame you. That’s what you have been told by instructors and other “industry” types. It just doesn’t happen to be true. And hasn’t been true for many years.
Richard Collins and I have written many times that the takeoff and initial climb is the most common phase of flight for a serious stall accident. And the departure stall is the deadliest. But pilots either don’t believe us, or the myth of the base-to-final stall is simply too enormous for anybody to dethrone.
As usual, there is a caveat in the numbers. If you look only at homebuilts the deadly traffic pattern stall accident still dominates. But that fact also shines a light on the progress made in the certified world, and the very difficult and perhaps impossible task of reducing the number of takeoff/departure stall accidents.
I hadn’t run the stall accident numbers in several years, but the American Bonanza Society has. I recently completed the ABS online proficiency training course for my flight review and the section on stalls reminded me that nothing much has changed. In the Bonanza series takeoff/departure stall accounted for 40 percent of the stall accidents compared to 34 percent on landing. If you add the stall accidents that happened during missed approach or balked landing the power-on climbing away stall accident is even more common than one happening during approach or landing.
More importantly, no Bonanza stalled in the traffic pattern during the 10 years studied. And most landing stalls occurred over the runway and serious injury was uncommon. The takeoff/departure stalls, however, were most often fatal or caused serious injury.
This wasn’t always true. At one time, just as in the homebuilt record, traffic pattern stall accidents dominated the certified world, and were often fatal. The change in that record had to come from improved flying qualities designed into production airplanes.
A stall accident is caused by a combination of pilot decisions and airplane behavior. The pilot decision part comes when, for whatever reason, the pilot exceeds the stalling angle of attack. The airplane flying qualities component comes after the stall happens.
The Bonanza is a perfect example of how understanding of, and acceptance of, stall behavior changed over the years. The Model 35 Bonanza was designed right after the end of World War II and certified in 1947. Anybody who has flown one knows the V-tail Bonanza will almost certainly drop a wing very rapidly when stalled with full flaps. In 1947 that was perfectly “normal” and acceptable.
In 1984 Beech redesigned the control system in the A36 Bonanza to install dual control yokes in place of the original central control column. Because the control cable runs and other components were changed the “new” A36 went through a full flying qualities test. The wing drop at stall was still there, but no longer acceptable.
Beech devised big wedge shaped vortex generators to mount on the leading edge just ahead of the flap-aileron junction, and the A36 also has limited elevator travel. The VGs keep the ailerons active and effective through the stall to help keep the airplane level, and the elevator travel limits prevent pilots from driving the A36 to a seriously high angle of attack. In fact at higher weights or forward CG the A36 may not even stall in the conventional nose-down sense but enter a sink-mush.
A sink-mush or wings level stall can still lead to an accident, but as the Bonanza landing stall accident record shows, the results are much more survivable than the snap roll and sharp nose down pitch of some other designs.
The problem is that improved stall behavior and flying qualities can do little to resolve the takeoff/departure stall accident. The reason is that on takeoff pilots stall because they have no chance for continued flight. The airplane isn’t climbing over the terrain, trees or some other obstruction ahead and the pilot’s choice is to pull back and hope for enough climb, or fly full speed into the “wall.”
The takeoff/departure stall accident can’t be prevented by more training or improved airplane stall characteristics. The accident happens because the pilot decided the airplane can complete the takeoff when it really lacks the performance to do so. High and hot conditions, wind, contaminated runway surface and other factors all contribute, but they are not causes. Only the pilot’s belief that the airplane can make it over the obstructions causes most takeoff stall accidents.
In the certified world we have seen nice progress in taming the traffic pattern maneuvering and landing stall but almost none in resolving the departure stall accident. If more training is to help it won’t be in the cockpit. It must be a course that somehow convinces pilots that physics, not flying skill, determine takeoff performance and required runway and clearway length. When a pilot leaves no margin for his takeoff no amount of pilot training or experience can get more climb performance than the airplane is able to give.