Which type of stall must be performed during a flight instructor-airplane practical test?

During a flight instructor-airplane practical test, the performance of a power-on or power-off stall is critical because these maneuvers directly relate to the handling of the aircraft in various flight conditions that an instructor must teach students. Power-on stalls simulate conditions that could occur during takeoffs and go-arounds when full power is applied. Power-off stalls mimic situations that may happen during descent and landing approaches.

Both types are essential for demonstrating proficiency in stall recovery techniques, as well as understanding the aerodynamic principles behind stalls, which are crucial for safe aircraft operation. Including both maneuvers showcases an instructor's ability to teach students about the effects of power on stall characteristics and recovery.

Meanwhile, options that involve accelerated stalls, straight and level stalls, or spiral stalls are less relevant in the context of the flight instructor's practical test requirements, as they do not represent the typical scenarios encountered during flight training which directly relate to pilot instruction.