What are the indications of an impending stall?

The correct indication of an impending stall includes a decrease in control effectiveness, an increased nose-up attitude, and aural stall warnings. As an aircraft approaches a stall, the flow of air over the wings becomes less effective at generating lift. This results in a noticeable reduction in control effectiveness, making it harder to maintain coordinated flight and requiring greater inputs to keep the aircraft level or to maneuver.

An increased nose-up attitude is also indicative of a possible stall situation. Pilots may find that the aircraft's nose has a tendency to pitch up more than normal as the critical angle of attack is approached, which is an important signal that the stall is imminent. Additionally, aural stall warnings activate to alert the pilots that the aircraft is nearing the stall condition, providing a critical warning that allows the pilot to take corrective action.

Understanding these signs is vital for a pilot to recognize the approach to a stall and to implement recovery procedures effectively. The other options do not accurately represent the indications of an impending stall, as they refer to conditions that are not typically associated with stall warnings or situational awareness during flight.