Any military guys here have any experience with a Position Homing Indicator (PHI)?

I'm curious if there's a tutorial about it's functionality and procedures publicly available...

Couldn't find anything in the current AF Instrument Flight Procedures manual.

Mods - feel free to move this to the military section if you think it's appropriate...I just didn't want to step on anyone's toes since they've got more serious business going on in there.