I’ve heard that aircheck before. I can only imagine what was going through their heads as this unfolded.
And, when I read the website that you posted with all the links about what happened that day, I found out I was ‘sort-of’ wrong about the system having never been tested nationally. In 1956, there was a national test of the CONELRAD system. It wasn’t the same as the EBS, but it was national, and stations actually signed off or re-tuned to their assigned CONELRAD frequencies. It only lasted about 15 minutes.
Wild. I had never heard of that before. Of course I was only a year old at the time.