Eric, I can't say how this is used in your neck of the woods, but the 121.5 frequency is often referred to around here as 'Guard'. Is it possible that you had a scrambled flight for some action - maybe someone wandering into a restricted zone? Perhaps a plane (42) was checking in there on his way to an intercept. Just a guess...no more than that 73s Mike
Mike, thanks for the perspective. That could be - I am monitoring a lot of mil air comms right now, mostly from STING (F-16/Toledo ANG). Plus, I am hearing small snippets from the UHF CLE ARTCC freqs interspersed with the STING traffic, so maybe that is it.
Pretty common. Around here it is anyway. I'll often hear various aircarft hailing another on guard such as Fedex xxx on guard” or United xx on guard” or sometimes it will be United xx center is looking for you on 129.4” Usually traffic to that effect. They'll quickly establish contact and switch to another freq.