There was a very similar incident in 1971 ("code word hatefulness"). Back then, three tapes were kept next to a EBS transmitter, two real alerts and one for testing. One day, an operator accidentally loaded the real alert rather than the correct test alert, and many stations prepared to tell the country the nuclear war was imminent.
The fix was to:
> …In the past three tapes, one for the test and two for actual emergencies, were hanging on three labeled hooks above the transmitter… In the future only the test tape will be left near the transmitter. The two emergency tapes [will be] be sealed in clearly marked envelopes and placed inside a nearby cabinet.
The fix was to:
> …In the past three tapes, one for the test and two for actual emergencies, were hanging on three labeled hooks above the transmitter… In the future only the test tape will be left near the transmitter. The two emergency tapes [will be] be sealed in clearly marked envelopes and placed inside a nearby cabinet.
http://conelrad.blogspot.com/2010/09/code-word-hatefulness-g...