How does altitude typically affect aircraft performance?

The correct choice indicates that aircraft performance generally decreases as altitude increases, and this is primarily due to the effects of air density on lift, engine performance, and propeller efficiency. As altitude rises, the air becomes less dense, which leads to a decrease in the amount of lift generated by the wings. Aircraft rely on the density of air to produce lift; therefore, as the altitude increases and the air thins, aircraft must fly at higher true airspeeds to maintain the same amount of lift.

Additionally, engine performance can also degrade with altitude. Most piston engines rely on air intake to mix with fuel for combustion and, at higher altitudes, the reduced air density means that less oxygen is available for combustion, resulting in a loss of engine power. While turbine engines are more efficient at higher altitudes compared to pistons, they also see changes in performance characteristics due to lower air density.

The efficiency of propellers also diminishes at higher altitudes because propellers generate thrust based on the density of the air through which they operate. With less dense air, they cannot generate thrust as effectively as they can at lower altitudes.

The other options do not accurately reflect the concerns of aircraft performance in relation to altitude. Performance improving with higher altitude suggests