How does higher altitude affect the engine's performance?

Higher altitude affects the engine's performance primarily because of the reduction in air density as altitude increases. As an aircraft climbs, the air becomes thinner, which means there are fewer oxygen molecules available for combustion in the engine. Engine performance is reliant on a proper mixture of fuel and air, and with less air available, the engine cannot produce as much power. This is particularly significant for piston engines, like the one in a Cessna 152, as they depend on air density for the intake of oxygen required for combustion.

Therefore, the decrease in air density reduces the overall engine power output, leading to a decline in climb performance and possibly requiring a longer distance to take off compared to sea level.

The indication that higher altitude might improve performance, as suggested by another choice, overlooks this critical interaction between air density and engine function. The statement about no effect on performance and the one regarding increased fuel consumption do not correctly capture the dynamics involved in engine operation at altitude. While higher altitudes can lead to an increase in fuel consumption per unit of power due to the need for a richer fuel mixture, the fundamental impact on power output remains a reduction due to lower air density.