A student pilot confuses angle of incidence with angle of attack. Which statement correctly distinguishes the two?
- AAngle of attack is fixed by the manufacturer, while angle of incidence changes with pitch attitude in flight
- BAngle of incidence increases sharply during a stall while angle of attack remains constant
- CAngle of incidence is a fixed value set by how the wing is rigged to the fuselage, while angle of attack is a variable angle between the chord line and the relative wind that changes with flight attitude
- DAngle of incidence and angle of attack are two names for the same angle and always change together
Show answer & explanationAnswer & explanation
Correct answer: C. Angle of incidence is a fixed value set by how the wing is rigged to the fuselage, while angle of attack is a variable angle between the chord line and the relative wind that changes with flight attitude
Angle of incidence is a fixed, structural angle designed into the airplane between the wing chord line and the longitudinal axis of the fuselage; it does not change in flight. Angle of attack, by contrast, is the variable angle between the wing chord line and the relative wind, which changes constantly with pitch attitude, airspeed, and flight path.
Why the other options are wrong
- A. This reverses the definitions; angle of incidence is the fixed one, and angle of attack is the variable one.
- B. Angle of attack increases toward the critical angle during a stall; angle of incidence remains unchanged since it is structurally fixed.
- D. These are distinct angles; incidence is fixed by design while attack varies continuously in flight.
Angle of Incidence vs Angle of Attack
Angle of incidence is the fixed angle between the wing chord line and the fuselage's longitudinal axis, set at manufacture. Angle of attack is the variable angle between the wing chord line and the relative wind, changing continuously in flight.
- Angle of incidence: fixed, structural, does not change in flight
- Angle of attack: variable, aerodynamic, changes with pitch and relative wind
- Angle of attack determines lift and stall, not angle of incidence
Memory trick: Incidence is 'installed' (fixed); attack is 'active' (variable)