Certified Flight Instructor - Flight Instructor Airplane Practice Exam

What effect does a decrease in air temperature have on aircraft performance?

1. It increases engine performance.

2. It decreases lift due to reduced air density.

3. It increases drag due to denser air.

4. It has no effect on aircraft performance.

The correct answer is: It increases engine performance.

A decrease in air temperature has a significant impact on aircraft performance, primarily because it generally increases engine performance. This occurs because colder air is denser than warmer air, which enhances the efficiency of both the engine and the airflow over the wings. With air being denser, there is more oxygen available for combustion in the engine, which can lead to better thrust production. Furthermore, denser air improves the wings' lift capability since lift is directly related to air density. The increase in air density due to lower temperatures also affects drag; despite the misleading implication of increased drag, it is the increase in lift and engine performance that predominantly benefits the aircraft's overall performance in colder temperatures. Therefore, while drag may be higher in denser air, this is offset by the benefits in lift and engine performance. Understanding these principles is crucial for pilots to effectively manage aircraft performance in varying temperature conditions.