An Aid to Navigation can be considered off station if its location by GPS measurement is greater than 150 feet, plus the GPS accuracy at the time of measurement, from the location given in the Light List. The GPS location shall be determined by taking at least three waypoints at one minute intervals and averaging the latitude, longitude and accuracy readings. If these requirements are met, the discrepancy may be reported to the USCG by their online discrepancy reporting system, VHF radio or cell phone and a Nautical, ATON report may be submitted in CCWeb. The calculations and / or plots used to determine the discrepancy shall be included in the report.
If these requirements are not met, the audit may be reported to the USCG by unofficial means (e-mail to the USCG Waterways Management Officer for the area for example) and an inspection report may be submitted in CCweb.