What is the maximum allowable deviation for a transponder to remain serviceable?

The maximum allowable deviation for a transponder to remain serviceable is 125 feet. This standard is established to ensure that transponders provide accurate altitude reporting, which is essential for maintaining safe separation between aircraft in controlled airspace. Accurate altitude reporting enables air traffic control to effectively manage air traffic and avoid potential collisions. If a transponder deviates beyond this limit, it can lead to significant safety concerns, as it may not reflect an aircraft's true altitude, resulting in erroneous information being communicated to air traffic control and potentially affecting situational awareness for pilots.

The specified threshold of 125 feet is part of regulatory guidelines intended to ensure that transponders function reliably within the parameters necessary for safe operation. As such, adherence to this standard is crucial for the safety of all aircraft operating in a given airspace.