The Colorado Search and Rescue Association is promoting FRS (Family Radio Service) Channel 3 as "the default during backcountry search and rescue (backcountry SAR) emergencies." FRS channel 3 is the same as GMRS (General Mobile Radio Service) channel 3. There is more GMRS info here ( https://www.k0nr.com/wordpress/2021/07/use-gmrs/ ) . To keep things simple,
no CTCSS ("privacy code") is used...carrier squelch only. See the CSAR announcement here: FRS Radio Use for Backcountry ( https://coloradosar.org/frs-radio-use-for-backcountry-sar-position-paper-04-10-23/
) .