Separation Anxiety

If there were some way I could make a series of trips back in time to change things, one of the stops on my itinerary would be to somehow infiltrate the small cadre of early pilots and airplane designers to convince them to use a word other than stall to describe what happens when a wing exceeds its critical angle of attack. The word obviously has numerous other applications, and using it for this purpose has confounded student pilots and television news anchors ever since. That said, Im not sure what should replace it, and remain open to suggestions.

Editorial Staff

Sunday, September 23, 2018 at 12:00 AM ET

Verified

Key Takeaways:

The article highlights that a fundamental misunderstanding of aerodynamic stalls (flow separation when the critical angle of attack is exceeded) and the limitations of "stall speed" contribute significantly to preventable Loss of Control In-flight (LOC-I) accidents.
It advocates for Angle of Attack (AoA) indicators as a superior and more direct measure of proximity to flow separation compared to indirect stall speed, particularly under accelerated or maneuvering flight conditions.
Maneuvering flight, especially banking and turning, drastically increases a wing's angle of attack and load factor, heightening the risk of flow separation and potential spin entries due to complex aerodynamic effects like differential lift and aileron deflection.

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If there were some way I could make a series of trips back in time to change things, one of the stops on my itinerary would be to somehow infiltrate the small cadre of early pilots and airplane designers to convince them to use a word other than “stall” to describe what happens when a wing exceeds its critical angle of attack. The word obviously has numerous other applications, and using it for this purpose has confounded student pilots and television news anchors ever since. That said, I’m not sure what should replace it, and remain open to suggestions.

After all, what single word, if any, concisely describes what happens when air flows over an airfoil at low angles of attack but then separates and stops flowing as that angle of attack exceeds a specific value? How to explain that aerobatic and inverted flight depend on excess power and brute force as much as they do training and practice? That there’s no magic geometry exempting the wing from its behavior at high angles of attack? Why is any of this a concern to us?