Story time!

Long time ago I was a radar technician on a HAWK battery. Specifically this illuminator unit

One day the alarm goes off because during a routine checkup, the contol center detected a suspicious aircraft approaching from the east: "take positions! this is not a drill!" Everyone in the roster runs to where they belong, everybody else takes cover, either way we're all getting ready for action. But moments later, the guys at the control rescan the sky and calm us because it was a false alarm. The officer in charge joked: "Probably just a flock of big birds flying too fast". Next day, same story again, only this time the aircraft was approaching from the north. Officer is now a bit more concerned, but still dismissive. A week goes by quitely, so we almost forget about the whole thing. Then it happens again. And again.

Top brass is now very concerned: of course, they were bothered of the problem itself, but they were especially worried of a "cry wolf" effect - that we won't respond well upon a true alarm. All resources now go to fixing it: at first, the usual "restart all systems" medicine, followed by earlier-than-scheduled maintenance to some pieces of equipement, and finally taking apart every serviceable module and testing it separately. Experts from across the country begin to arrive, trying to advise us, but to no avail.

After two months, a junior literally stumbled upon the root cause: a fluorescent drop light.

For years incandescence drop lights have been in use, until someone decided it's time to save some energy. Turns out even when they were off, but still plugged in, they somehow resonated with our instruments. For example, if we left the light hanging on the south side of the unit, the unit would misidentify it as an aircrapt approaching from the south.

The new ordinance was to always unplug the lights after using them. And just to be on the safe side? We returned to the energy wasting lights.