A few more thoughts about this...
Watch the movie Failsafe, or at least read the Wikipedia synopsis of it. Since I'm not paying attention to such things, I don't know if we still do it, but we probably at least practice...
...We used to keep bombers in the air at all times. They would scramble and fly to a predetermined point. At that point, what's supposed to happen is a code is sent to the bomber crew with mission abort instructions. Those instructions were sent via several redundant means, including coded voice messages sent via HF SSB circuits.
Those voice messages sounded exactly like what you're hearing.
As a kid, I could dial up a few known frequencies around 9 and 11 MHz, and almost any day hear things like that. I also heard McClellan AFB making similar transmissions, as well as March AFB a few times. Most of the time it was a code word used as a callsign, so I had no idea who it was. When the band was open, I'd hear the same message repeated out several times over several different transmitters, some strong, some weak and fluttery from multiple hop skip. They definately wanted their message to be heard.
Presumably, if the abort codes didn't reach their destination, the bomber crews would open up the sealed orders of the day carried by the flight crew, and carry out the orders.
I suspect most of the time the coded message is dull routine stuff. But we're not supposed to know either way.
