During a ground check point for an instrument takeoff, the altimeter must be within how many feet of a known elevation point?

For an instrument takeoff, the altimeter must be checked to ensure its accuracy in relation to a known elevation point. The standard requires that the altimeter be within 75 feet of the known elevation. This ensures that the aircraft is accurately representing its altitude and helps maintain safety during the takeoff phase.

Maintaining a precise altimeter setting is critical for avoiding terrain and ensuring safe separation from obstacles. If the altimeter is not within the required limits, it could lead to potentially hazardous situations during takeoff, particularly in low visibility conditions where reliance on instruments is essential.

Thus, the limit of 75 feet allows for a satisfactory margin while ensuring aircraft performance remains within safe operating parameters. This standard aligns with accepted aviation regulations and practices to promote safety in the flight operations.