During a VOR ground checkpoint, what is the acceptable tolerance?

The accepted tolerance during a VOR ground checkpoint is indeed +/- 4°. This standard is established to ensure that VOR (VHF Omnidirectional Range) navigation systems are accurately functioning within a specific range. The rationale for this tolerance lies in the need for precise navigation information, which is critical for pilots to maintain situational awareness and navigate safely.

A VOR system is used extensively in aviation for determining the aircraft's direction relative to ground-based navigational aids. During the ground check, a pilot or technician verifies the accuracy of the VOR signal by comparing the indicated radial to the known magnetic heading. A discrepancy greater than the acceptable tolerance could indicate a miscalibration or malfunction of the VOR system, potentially leading to navigation errors in flight. Keeping the tolerance at +/- 4° minimizes the risk of significant navigational errors while allowing for the practical limitations of equipment variability. This standard ensures reliability and safety in navigation for aircraft pilots.