This is a survival radio that is carried in the emergency vest of air crew members. It can transmit a beacon (attention getting warble tone) on 243.0 MHz. Voice on 243.0 or 282.8 MHz and Morse Code in Modulated Continuos Wave (MCW) mode on 243.0. It will receive voice on 243.0 and 282.8 MHz. The previous frequencies are for Military emergency communications. The PRC-90 does not work on the civilian emergency frequency of 121.5 MHz nor does it work on the international distress frequency of 406.025 MHz.