Which of the following is NOT a prohibited maneuver in the aircraft?

Standard stalls are maneuvers that are not prohibited because they are essential for pilot training and understanding of aircraft behavior during low-speed flight conditions. These stalls are used to teach pilots how to recognize, recover from, and manage stalls, which is critical for maintaining safety in flight. Standard stalls are typically conducted in a controlled manner to ensure that pilots can practice recovery techniques without compromising safety.

In contrast, inverted stalls, inverted spins, and aggravated spins are considered prohibited maneuvers because they can lead to dangerous flight conditions that are difficult to recover from, particularly in the T-6. These maneuvers can lead to excessive loss of control or structural failure, which is why they are not permitted during flight operations. Prioritizing safety and proper aircraft handling is essential, hence the allowance of standard stalls within training parameters while prohibiting the others.