The operation of an angle of attack indicating system is based on the detection of differential pressure at a point where the airstream flows in a direction

The operation of an angle of attack indicating system is based on the detection of differential pressure at a point where the airstream flows in a direction

• A. Parallel to the travel of the aircraft
• B. Not at all dependent on air flow
• C. Not parallel to the travel of the aircraft
• D. Only at high speed

Answer: (C)

An angle of attack indicator relies on the pressure difference created by airflow hitting a sensing point at an angle relative to the flight path. The ports or sensing head are exposed to the local airstream in a direction that is not parallel to the aircraft’s travel, so as the angle of attack changes, the flow direction relative to the sensor changes and a measurable differential pressure is produced. This pressure difference correlates with how high the nose is pitched relative to the oncoming air, giving the AOA reading. If the flow were parallel to the travel direction, the pressure difference across the sensor would be minimal and provide little information about angle of attack. The system doesn’t require high speed to function; it responds to the angle between the airstream and the aircraft, not to speed alone.

An angle of attack indicator relies on the pressure difference created by airflow hitting a sensing point at an angle relative to the flight path. The ports or sensing head are exposed to the local airstream in a direction that is not parallel to the aircraft’s travel, so as the angle of attack changes, the flow direction relative to the sensor changes and a measurable differential pressure is produced. This pressure difference correlates with how high the nose is pitched relative to the oncoming air, giving the AOA reading.

If the flow were parallel to the travel direction, the pressure difference across the sensor would be minimal and provide little information about angle of attack. The system doesn’t require high speed to function; it responds to the angle between the airstream and the aircraft, not to speed alone.