Definition
A radar or surveillance track that has drawn the attention of air defense or air traffic personnel because its behavior, identification, or flight profile suggests it may pose a security concern and requires closer monitoring or further action.
Plain English
An aircraft showing up on radar that controllers or air defense people have decided to watch more carefully because something about it looks unusual or potentially concerning.
Context Anchor
Seen in FAA security, air traffic monitoring, and intercept-related discussions, especially when an aircraft is not communicating normally or is flying in a way that raises concern.
Derivation
‘Track’ comes from the radar sense of a continuous trail of position reports for a single aircraft. ‘Of interest’ flags it for attention. Together the phrase means a radar return that has been singled out for closer watching — not yet confirmed as a threat, but no longer ignored.
Why Pilots Care
A pilot whose aircraft becomes a TOI may receive special instructions or be subject to closer monitoring that affects routing or communications.
Intuition Check
“Interest” does not mean casual curiosity here. In this FAA context, it means the aircraft’s observed flight path has been flagged for closer monitoring until the concern is resolved.
Example Sentence 1
After the aircraft entered restricted airspace without clearance, it was designated a track of interest and fighters were launched to intercept.
Example Sentence 2
Radar showed the unknown aircraft as a TOI and vectored interceptors to investigate.