December 12, 2012

The FAA notified NBAA today that all North American Aircraft Geometric Height Measurement Element (AGHME) sites are currently out of service. AGHMEs are a key part of one method used to meet the periodic height monitoring requirement for aircraft authorized to fly in RVSM Airspace. The following information has been provided by the FAA to NBAA for dissemination to its Members.

Beginning 0000Z on Tuesday, December 11, 2012, we experienced a problem with the timing portion of the AGHMEs that prevents us from accurately measuring the altimetry system error of aircraft. This problem affects all AGHMEs. We are working with the manufacturer of the affected equipment and, while the solution is known, it must be converted into a firmware update for FAA use. Subsequently, this firmware update must be disseminated to our equipment and tested. We expect the testing to last approximately one week. Thus, the AGMHEs will not be operational until the end of testing. Please check the status of the AGHMEs at for further information.