Duress code. Yes, it’s a real term and it means “panic code,” or a code that you give instead of your “real” code to indicate that you’re in trouble. Or under duress. I had never heard of it until reading The Nike Historical Society’s excellent section about security at Nike installations.
One reader wrote in with an anecdote about duress codes:
I was escorting a Major around the [Nike Missile] Launching Area during — I think it was a NAICP test. When we approached the Exclusion Area guard shack he asked me to give the guard the duress code. I said I can categorically vouch that everyone knows the duress code and will take appropriate action. He said I want you to give the code. I reluctantly complied. The guard without hesitation through the Major to the ground and cocked his weapon and put it directly on his temple. I had to physically pull him off and explain it was only a test and that there was no threat. It took some convincing but the guard backed off. I don’t think the Major ever did that again.
Here is a video some guy shot at the restored Nike Missile installation on the Marin Headlands, just north of San Francisco. It could benefit from some editing, so just skip ahead to -1:00 so that you can see the beginning of the launch process, where the missile is raised.