“To the military/intelligence/air traffic control, a “UFO” is a flying object without a transponder”
Not exactly.
Many aircraft fly all over the US, outside controlled airspace, and they don’t have a transponder. I takeoff from an uncontrolled field and don’t squawk does not make me a UFO as commonly understood.
A transponder is a code that if flying VFR the pilots dial in 1200 and that means nothing until the pilot identifies himself to ATC, either through squawking ident or through verifying location via ground reference or some other identifying maneuver.
UFO means Unidentified Flying Object, meaning just that. . .it was flying and unidentified.
I never said EVERY flying object is a UFO. You’re right in that UFOs are only planes (and yes, other things) that SHOULD have a transponder to be flying where they are and don’t.
I used to go to my Dad’s work at the FAA. There were various radar CRTs scattered outside the control tower. (I guess they were for testing?) I used to play on them and watch the UFOs go by. Where we were, they were most commonly planes going back and forth to Cuba.