Definition
On an Angle of Attack (AOA) indicator, the calibrated reference point that represents zero lift — the angle of attack at which the wing produces no lift. All other AOA values shown on the indicator are measured relative to this reference.
Plain English
It is the spot on the AOA gauge that stands for the wing angle where the wing makes no lift at all. Every other reading on the gauge is measured from this starting point.
Context Anchor
Seen when reading about how angle of attack indicators are installed, adjusted, or interpreted.
Derivation
“Zero” means no amount on the chosen scale, and “set point” means a value an instrument or system is adjusted to use as a reference. Together, the phrase means the zero value chosen during calibration, not just any condition that happens to look level in flight.
Why Pilots Care
An incorrect zero set point produces misleading AOA readings that can hide true stall margins or safe operating limits.
Intuition Check
Do not assume “zero” means the airplane is level or the nose is on the horizon. Here, “zero” means the reference value the angle of attack indicator has been adjusted to use as its starting point.
Example Sentence 1
Before the AOA indicator can give accurate readings in flight, the technician must establish the zero set point during installation.
Example Sentence 2
With the zero set point properly established, the pilot could trust the AOA indicator to show safe approach values.