I spent my last 7 years in an AH-64 Attack unit. We had the new (at that time) ANVIS/AVS-6. A pair came up missing once. oy. It was worse than losing an M-16 or M-60. We weren't allowed to even breathe until they were found.
Heh, heh! I flew Hueys in RVN and kept up my minimums in the OH-58A (aka the Frisbee) ever afterward since I am originally a tanker. RLO at first, break in service, retired last year as a warrant.
Think that AVS-6 lockdown was bad? Try losing a serial numbered cash collection sheet! AR sez the responsible officer gets a statement of charges for the maximum amount possible on the missing sheet (per diem plus meal cost). But the new Xerox machine and new whiteout came to the rescue and a new CCS was forged from the specimen in the AR and everyone re-signed it until the cash on hand balanced, both were turned in, and that was that.
Geez, I miss those days!
;^)