High false alarm rate makes first-alert launch unfeasible. Absent independent distress corroboration, RCCs must wait for additional alert information. Same as 406 MHz. Average subsequent satellite passes every 60 minutes. Same as 406 MHz.
Alerts are anonymous.
121.5 MHz technology not capable of transmitting data. Near instantaneous detection by geostationary satellites. System provides world-wide coverage. Position calculated by doppler shift analysis. Position calculated by doppler shift analysis.