What is the correct altitude check procedure during an inadvertent departure from controlled flight?

The correct altitude check procedure during an inadvertent departure from controlled flight is to check altitude. This step is crucial as it helps the pilot understand the current vertical position of the aircraft when experiencing unusual attitudes or loss of control. Knowing the altitude aids in assessing the situation and planning the next course of action to regain control, such as executing recovery techniques or initiating a climb if altitude permits.

While other options may seem relevant to the overall management of the aircraft during a flight, they do not directly address the immediate need to assess altitude in an emergency scenario. For instance, retracting flaps or adjusting the power control lever may not be pertinent until the aircraft's position is stabilized and the altitude situation is understood. Similarly, monitoring airspeed is also important, but it is secondary to first ensuring altitude awareness and addressing any immediate altitude-related risks.