“they can’t go undetected by maintenance and crew”
Just another data point.
On MonkeyWerx 02-04-2025 episode, he mentioned that the “Hex Code” for this aircraft was not in the “Master Database” until after the crash.
The initial report that it was a “Gold Top” ended up being wrong.
???
Who made the report, the unit? I doubt it. Probably inferred by the 'Gov't Continuity Mission' designation.
Not me:
HEX Code is a unique ICAO 24-bit address used to identify the aircraft and broadcast by its Mode-S transponder123. It is assigned to all modern aircraft upon national registration and becomes a part of the aircraft’s Certificate of Registration3. Normally, the hex code is never changed, but the onboard transponders can be re-programmed12.