What is the maximum allowable error in feet for an altimeter to be considered in tolerance for flight?

To determine the maximum allowable error for an altimeter to be considered in tolerance for flight, it is essential to refer to the standards set forth by regulatory authorities. In general aviation, the tolerance for altimeter error is specified to ensure that pilots have accurate altitude information during their operations, which is critical for maintaining safe vertical separation from terrain and other aircraft.

The acceptable variance is usually defined as 75 feet. This means that if an altimeter reads within 75 feet of the true altitude, it is considered to be functioning properly and within the acceptable tolerance range. This standard helps ensure that pilots can rely on their altimeter readings to navigate safely.

The other options reflect error ranges that exceed this limit, which would make the altimeter unreliable for safe flight operations. Therefore, 75 feet is the correct answer as it aligns with the established guidelines for altimeter tolerance in aviation.