It may be Super Bowl Sunday to football fans, but this weekend also marks the cessation of satellite monitoring for aircraft emergency locator transmitters that transmit only on 121.5 MHz. Search and rescue units will continue to monitor the old frequency, at least here in the United States, while also guarding the new ELTs frequency, 406 MHz. U.S. aircraft operators are not yet required to install new 406 MHz ELTs, which also incorporate a transmitter operating on 121.5 MHz. For U.S. operators who plan trips to Canada, Mexico or the Bahamas, the rules are more complex. Canada does not require 406 MHz ELTs yet and is planning a two-year transition period, but has yet to finalize its plan. Mexico will allow aircraft with 121.5 MHz equipment to use its airspace at least until the end of June (unless they reach mandatory ELT battery replacement deadlines in the meantime). And the regulatory authority in the Bahamas will not require 406 MHz ELTs for flying in its airspace until at least January 2011. Since satellites will no longer 'hear' a distress call on 121.5, pilots are advised to monitor that frequency on their second radio.