SIFT Army Aviation Practice Test 2026 – Complete Exam Prep

An increase in altitude typically decreases RPM due to the reduction in air density. As altitude rises, the air becomes thinner, which means there is less air available for the rotor blades to generate lift. In aviation, especially in rotorcraft, reduced lift requires adjustments in engine power and rotor speed to maintain proper flight performance.

This reduced air density directly impacts the engine's ability to produce power efficiently. As the rotorcraft ascends to higher altitudes, the engines often need to work harder to maintain the same amount of thrust, which can lead to decreased RPM if the power output of the engine is not sufficient to compensate for the altitude change.

In contrast, the other choices do not accurately reflect the relationship between altitude and RPM. While an increase in altitude does lead to decreased RPM, fluctuations in RPM can occur due to various factors such as changes in wind or pilot input, but these do not represent a consistent effect of altitude on RPM. Therefore, the correct understanding is that altitude has a direct correlation with RPM reduction due to the effects of air density on rotorcraft performance.