Apparatus

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sensors Mode-S transponder

A261A4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N25221 · CESSNA 152 · operated by HILLSBORO AERO ACADEMY LLC

Hex
A261A4
Octal
50460644
Decimal
10,641,828
Country
US
Tail
N25221
Type
C152
No current signal · last broadcast 8h ago
Flights observed
173
Distinct callsigns
1
Country
US
Last broadcast
8h ago

Last known position

Most recent position reported by Mode-S A261A4.

Country allocation

The ICAO 24-bit address A261A4 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 1 distinct

Callsign Airline Flights Last seen
N25221 - 173 2026-07-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 N25221 - Jul 14, 02:30 UTCJul 14, 04:20 UTC1h 50m
2026-07-13 N25221 - Jul 13, 20:30 UTCJul 13, 21:05 UTC35m
2026-07-13 N25221 - Jul 13, 19:00 UTCJul 13, 19:40 UTC40m
2026-07-13 N25221 HIO → HIO Jul 13, 17:25 UTCJul 13, 17:50 UTC25m
2026-07-13 N25221 - Jul 13, 16:35 UTCJul 13, 17:20 UTC45m
2026-07-12 N25221 - Jul 12, 23:55 UTCJul 13, 01:45 UTC1h 50m
2026-07-12 N25221 HIO → MFR Jul 12, 19:10 UTCJul 12, 22:00 UTC2h 50m
2026-07-12 N25221 - Jul 12, 18:10 UTCJul 12, 18:20 UTC10m
2026-07-12 N25221 HIO → HIO Jul 12, 17:25 UTCJul 12, 18:05 UTC40m
2026-07-12 N25221 HIO → HIO Jul 12, 03:40 UTCJul 12, 05:10 UTC1h 30m
2026-07-07 N25221 - Jul 7, 18:25 UTCJul 7, 19:45 UTC1h 20m
2026-07-07 N25221 HIO → HIO Jul 7, 14:25 UTCJul 7, 16:05 UTC1h 40m
2026-07-07 N25221 - Jul 7, 00:30 UTCJul 7, 01:30 UTC1h 0m
2026-07-06 N25221 - Jul 6, 17:25 UTCJul 6, 17:55 UTC30m
2026-07-06 N25221 - Jul 6, 15:40 UTCJul 6, 16:50 UTC1h 10m
2026-07-06 N25221 - Jul 6, 01:40 UTCJul 6, 03:35 UTC1h 55m
2026-07-05 N25221 - Jul 5, 18:35 UTCJul 5, 20:40 UTC2h 5m
2026-07-05 N25221 - Jul 5, 14:55 UTCJul 5, 15:35 UTC40m
2026-07-04 N25221 - Jul 4, 15:30 UTCJul 4, 18:00 UTC2h 30m
2026-07-04 N25221 - Jul 4, 13:30 UTCJul 4, 13:50 UTC20m
2026-07-04 N25221 - Jul 4, 12:10 UTCJul 4, 12:25 UTC15m
2026-07-04 N25221 - Jul 4, 11:00 UTCJul 4, 11:30 UTC30m
2026-07-03 N25221 - Jul 3, 19:05 UTCJul 3, 20:35 UTC1h 30m
2026-07-03 N25221 RDM → RDM Jul 3, 16:15 UTCJul 3, 17:45 UTC1h 30m
2026-07-03 N25221 - Jul 3, 14:05 UTCJul 3, 15:25 UTC1h 20m
2026-07-03 N25221 - Jul 3, 00:30 UTCJul 3, 00:50 UTC20m
2026-07-02 N25221 - Jul 2, 23:25 UTCJul 2, 23:40 UTC15m
2026-07-02 N25221 RDM → RDM Jul 2, 18:40 UTCJul 2, 21:10 UTC2h 30m
2026-07-02 N25221 - Jul 2, 16:10 UTCJul 2, 17:35 UTC1h 25m
2026-07-02 N25221 RDM → RDM Jul 2, 14:25 UTCJul 2, 15:20 UTC55m
2026-07-01 N25221 - Jul 1, 17:15 UTCJul 1, 18:25 UTC1h 10m
2026-07-01 N25221 RDM → RDM Jul 1, 14:30 UTCJul 1, 15:35 UTC1h 5m
2026-07-01 N25221 RDM → RDM Jul 1, 04:40 UTCJul 1, 04:55 UTC15m
2026-06-30 N25221 RDM → RDM Jun 30, 16:45 UTCJun 30, 17:40 UTC55m
2026-06-30 N25221 RDM → RDM Jun 30, 05:35 UTCJun 30, 06:05 UTC30m
2026-06-29 N25221 RDM → RDM Jun 29, 20:44 UTCJun 29, 22:00 UTC1h 15m
2026-06-29 N25221 MDJ → RDM Jun 29, 17:34 UTCJun 29, 18:05 UTC30m
2026-06-29 N25221 - Jun 29, 16:25 UTCJun 29, 16:59 UTC35m
2026-06-29 N25221 - Jun 29, 13:39 UTCJun 29, 14:50 UTC1h 10m
2026-06-29 N25221 RDM → RDM Jun 29, 05:09 UTCJun 29, 06:44 UTC1h 35m
2026-06-28 N25221 - Jun 28, 23:44 UTCJun 29, 01:14 UTC1h 30m
2026-06-28 N25221 - Jun 28, 18:55 UTCJun 28, 20:25 UTC1h 30m
2026-06-28 N25221 RDM → RDM Jun 28, 16:35 UTCJun 28, 17:50 UTC1h 15m
2026-06-28 N25221 RDM → RDM Jun 28, 14:59 UTCJun 28, 15:49 UTC50m
2026-06-27 N25221 RDM → RDM Jun 27, 14:09 UTCJun 27, 15:39 UTC1h 30m
2026-06-26 N25221 RDM → RDM Jun 26, 19:20 UTCJun 26, 20:44 UTC1h 25m
2026-06-26 N25221 - Jun 26, 03:24 UTCJun 26, 03:54 UTC30m
2026-06-26 N25221 - Jun 26, 00:50 UTCJun 26, 01:24 UTC35m
2026-06-25 N25221 RDM → RDM Jun 25, 19:49 UTCJun 25, 20:54 UTC1h 5m
2026-06-25 N25221 RDM → RDM Jun 25, 16:59 UTCJun 25, 18:59 UTC2h 0m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the N25221 page for operator, model, and routing details .

Mode-S A261A4 frequently asked

What is Mode-S code A261A4?
A261A4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N25221.
Where is Mode-S A261A4 registered?
Mode-S code A261A4 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A261A4 broadcasting right now?
No active broadcast right now. Last signal was 8h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A261A4, octal 50460644, decimal 10,641,828.
What flights does A261A4 operate?
Mode-S A261A4 has broadcast 1 distinct callsign, including N25221.