After 10 years or so responding / operating in the SAR environment, our SOP's, if we are in the poo, are to communicate on all appropriate VHF frequency's (the first being Area if we have established coms then 121.5) and whatever other means we have available at the time and THEN turn on the ELT / PLB .... the rational being when the ELT / PLB is activated communications on 121.5 (and frequencies close to this) may not be possible due to the homing signal.