Answer:
The safety and distress calling frequency established and accepted in the United States, depends on whether it is used by a civilian, or military group, or if it is for air, or maritime communications. In essence, regardless of the purpose of the safety and distress frequency, in general, these are communications channels that have been authorized and accepted by the Federal Communications Comission (FCC), as a means of communication in case it is necessary to convey a sense of emergency, or need. If the frequency is maritime, then the correct frequency is channel 16 (156.8 MHz). And in air, the correct frequencies as per the FCC are: 121.5 MHz for civilians, also known as International Air Distress, and in military, it is 243.0 MHz, also known as Military Air Distress.