Certified Flight Instructor - Flight Instructor Airplane Practice Exam

How do warmer-than-standard temperatures affect the indication of a sensitive altimeter?

1. The aircraft will be higher than the altimeter indicates.

2. The aircraft will be lower than the altimeter indicates.

3. There is no effect on the altimeter indication.

4. Only the altimeter settings will change.

The correct answer is: The aircraft will be higher than the altimeter indicates.

When it comes to the operation of a sensitive altimeter, warmer-than-standard temperatures can lead to an upward error in altitude indication. This occurs because the sensitive altimeter is calibrated based on standard atmospheric conditions, which assume a lapse rate of temperature with altitude. In warmer-than-standard conditions, the air density decreases more slowly with altitude than it would under standard conditions. As a result, when an aircraft is flying at a certain pressure altitude, the altimeter will read a lower altitude than the aircraft's true altitude. Therefore, the aircraft will be higher than what is indicated on the altimeter. Understanding this phenomenon is crucial for pilots, particularly for ensuring safe flying practices, as it highlights the importance of adjusting flight levels or using altimeter settings accurately to maintain proper altitude, especially when operating in areas where temperature deviations from standard conditions may occur.