FAA Instrument Flight Instructor (FII)Instruments and SystemsMedium
During a rapid acceleration on the takeoff roll in a conventional vacuum-driven attitude indicator, the instrument will typically display which erroneous indication, even though the aircraft is actually still on the ground and level?
- AA false left bank indication
- BA false nose-up (climb) indication
- CA false nose-down (dive) indication
- DNo error occurs during linear acceleration
Show answer & explanationAnswer & explanation
Correct answer: B. A false nose-up (climb) indication
Acceleration errors in a vacuum-driven attitude indicator cause the gyro's pendulous vanes to erect improperly, resulting in a false nose-up (climb) indication during forward acceleration, such as on takeoff roll. This is similar in cause to the magnetic compass acceleration error but affects the AI's erection mechanism instead.
Why the other options are wrong
- A. Bank errors are not the typical result of straight-line acceleration.
- C. Acceleration produces a false climb indication, not a dive indication.
- D. Attitude indicators are subject to acceleration errors from their erecting mechanism.
Attitude Indicator Acceleration Error
An error in vacuum-driven attitude indicators where linear acceleration causes the erection mechanism to falsely display a nose-up (climb) attitude.
- Occurs during rapid acceleration, e.g., takeoff roll
- Caused by pendulous vane erection system reacting to inertial forces
- Deceleration produces the opposite false nose-down indication
Memory trick: Speed up, AI lies 'up' — just like compass ANDS on acceleration.