Certified Flight Instructor - Flight Instructor Airplane Practice Exam

How do temperature changes affect a sensitive altimeter?

1. Warmer temperatures lower the altitude indication.

2. Colder temperatures raise the altitude indication.

3. Warmer temperatures heighten the altitude shown.

4. Colder temperatures lower the altitude indication.

The correct answer is: Colder temperatures lower the altitude indication.

A sensitive altimeter measures altitude by comparing the atmospheric pressure outside the aircraft to a standard atmospheric pressure. This standard is based on assumptions about temperature. As temperature decreases, the air becomes denser, which results in higher pressure readings at a given altitude. Conversely, if the temperature increases, the air becomes less dense, leading to lower pressure readings at that altitude. When temperatures are colder than standard atmospheric conditions, the altimeter will indicate a higher altitude because the denser air causes the altimeter to measure more pressure than it would under standard temperature conditions. Thus, the altimeter will suggest the aircraft is at a higher altitude than it actually is. So, in situations where the temperature is colder than the standard or expected temperatures used for altimeter calibration, the result is a lower altitude indication than what is actual. This means that when colder temperatures are present, the true altitude will be lower than what the altimeter reads.