What principle does the angle-of-attack indicating system operate on?

The angle-of-attack indicating system operates on the principle of detecting differential pressure in the airstream. This system is designed to measure the difference in pressure created by the airflow over and under the aircraft’s wing as it changes attitude relative to the oncoming air.

When the angle of attack increases, the airflow over the wing changes, resulting in variations in pressure that the system can measure. By analyzing these pressure differentials, the angle-of-attack indicator provides critical information about the aircraft's aerodynamics, helping pilots to maintain optimal operating conditions to prevent stall situations.

The other choices do not align with the function of the angle-of-attack indicating system. Measuring temperature differences in the airflow, cockpit pressure changes, or calculating ground speed does not directly relate to determining the angle of attack, which specifically requires analyzing how the air pressure varies as the aircraft's angle with respect to the airflow changes.