Plain English Meaning
The wing angle that gives the airplane its best overall performance — the sweet spot where the wing produces the most lift for the least drag. Angle of attack indicators show this as a target mark the pilot can fly to directly.
Full Definition
The angle of attack that produces the most efficient overall performance for a given flight condition, typically yielding the best lift-to-drag ratio. On an angle of attack indicator, the OAA is shown as a specific reference mark that the pilot flies to when seeking maximum aerodynamic efficiency, such as for best glide, maximum endurance, or best range performance.
Context Anchor
Seen on angle-of-attack indicator displays, especially in diagrams or cockpit indications that show a target approach angle.
Derivation
‘Alpha’ is the Greek letter (α) used in aerodynamics as the symbol for angle of attack — the angle between the wing and the oncoming air. So ‘Optimum Alpha Angle’ literally means ‘the best angle of attack.’ Knowing that alpha = angle of attack makes the term immediately readable.
Why Pilots Care
Holding this angle improves fuel economy, range, and climb performance while keeping a safe margin from stall.
Intuition Check
“Optimum” does not mean the highest possible nose-up angle or the slowest possible speed. Here it means the target angle of attack the indicator is set up to show for the intended operation.
Example Sentence 1
After the engine failure, the pilot pitched to the OAA mark on the AOA indicator to achieve the best glide distance.
Example Sentence 2
In the traffic pattern the AOA needle settled on the OAA marking for a clean, stabilized approach with good energy management.