Private Pilot Private Exam

What is the purpose of setting the altimeter to a specific value?

1. To indicate true altitude at field elevation

2. To determine wind speed at different altitudes

3. To measure outside air temperature

4. To calculate the distance traveled during flight

The correct answer is: To indicate true altitude at field elevation

Setting the altimeter to a specific value is essential for indicating true altitude at the field elevation. Altimeters are calibrated to measure the atmospheric pressure outside the aircraft, which changes with altitude. By setting the altimeter to a specific local pressure value, typically the altimeter setting provided by air traffic control or available weather reports, pilots ensure that their aircraft's altitude reading reflects the actual height above sea level. This practice is crucial for maintaining safe vertical separation from other aircraft and for ensuring accurate approaches and departures in airport operations. When the altimeter is correctly set, it helps pilots gauge their altitude accurately, which is vital for safe flying, especially in areas with varying terrain. The other options listed do not relate directly to the primary function of the altimeter. For instance, wind speed is determined through different methods, such as using an anemometer or wind direction indicators, not through the altimeter setting. Similarly, air temperature is measured using thermometers, and distances traveled are calculated based on groundspeed and time, not through altitude measurements. Thus, the importance of setting the altimeter correctly is focused on maintaining altitude accuracy relative to the field level.