Commercial Pilot License (CPL) 2025 – 400 Free Practice Questions to Pass the Exam

The key advantage of variable pitch propellers during altitude changes is their ability to maintain constant engine RPM. This is crucial for optimal engine performance because as altitude increases, air density decreases, which affects the amount of thrust that the propeller can generate. With a variable pitch propeller, the angle of the blades can be adjusted in response to these changes in altitude and air density.

When a pilot climbs to a higher altitude, the propeller can be adjusted to a finer pitch, allowing the engine to operate at its ideal RPM despite the lower air density. This adjustment helps to prevent the engine from over-revving, which can happen if the propeller pitch is fixed and cannot adapt to varying conditions. Consequently, by maintaining a constant engine RPM, the overall performance of the aircraft is enhanced, leading to better climb rates and efficiency during altitude changes.

While the other options present some benefits related to propeller design or engine operation, they do not directly address the adaptability of variable pitch propellers to maintain engine RPM during altitude changes, which is its primary advantage.