If an altimeter setting is not available before flight, to which altitude should the pilot adjust the altimeter?

If an altimeter setting is not available before flight, to which altitude should the pilot adjust the altimeter?

• A. The elevation of the departure area
• B. The elevation of the destination
• C. Sea level
• D. 1,000 ft above the departure area

Answer: (A)

When you don’t have an altimeter setting, use a known reference from where you’re starting. Setting the altimeter to the elevation of the departure airport gives you a grounded reference for your altitude as you lift off, so your reading reflects how high you are above that field. This provides a reliable baseline for maintaining safe clearance from terrain and obstacles as you begin the flight. Using the destination’s elevation would bias your readings toward the other end of the trip and could lead you to misjudge your actual altitude early in the flight. Setting it to sea level ignores local atmospheric pressure variations, which can differ from place to place. Picking a fixed offset, like 1,000 ft above the departure area, assumes a starting height that isn’t guaranteed, which can be dangerous. So, the best default is to set the altimeter to the departure area’s elevation.

When you don’t have an altimeter setting, use a known reference from where you’re starting. Setting the altimeter to the elevation of the departure airport gives you a grounded reference for your altitude as you lift off, so your reading reflects how high you are above that field. This provides a reliable baseline for maintaining safe clearance from terrain and obstacles as you begin the flight.

Using the destination’s elevation would bias your readings toward the other end of the trip and could lead you to misjudge your actual altitude early in the flight. Setting it to sea level ignores local atmospheric pressure variations, which can differ from place to place. Picking a fixed offset, like 1,000 ft above the departure area, assumes a starting height that isn’t guaranteed, which can be dangerous. So, the best default is to set the altimeter to the departure area’s elevation.