ENR 7.7 North Atlantic (NAT) Timekeeping Procedures

  1. Prior to entry into NAT High Level Airspace, the time reference system(s) to be used during the flight for calculation of waypoint estimated times of arrival (ETAs) and waypoint actual times of arrival (ATAs) must be synchronized to universal coordinated time (UTC). All ETAs and ATAs passed to air traffic control must be based on a time reference that has been synchronized to UTC or equivalent. Acceptable sources of UTC include:
    1. WWV − National Institute of Standards and Technology (Fort Collins, Colorado). WWV operates 24 hours a day on 2500, 5000, 10000, 15000, 20000 kHz (AM/single sideband (SSB)) and provides UTC voice every minute.
    2. GPS (corrected to UTC) − Available 24 hours a day to those pilots who can access the time signal over their shipboard GPS equipment.
    3. CHU − National Research Council (NRC) −Available 24 hours a day on 3330, 7335, and 14670 kHz (SSB). In the final 10−second period of each minute, a bilingual station identification and time announcement is made. Since April 1990, the announced time is UTC.
    4. BBC − British Broadcasting Corporation (United Kingdom). The BBC transmits on a number of domestic and worldwide frequencies and transmits the Greenwich time signal (referenced to UTC) once every hour on most frequencies, although there are some exceptions.
    5. Any other source shown to the State of Registry or State of Operator, as appropriate, to be an equivalent source of UTC.