Apparatus

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sensors Mode-S transponder

A1F4B1

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N225MK · CIRRUS SR-22T Turbo · operated by OXFORD ADVISORY AVIATION LLC

Hex
A1F4B1
Octal
50372261
Decimal
10,613,937
Country
US
Tail
N225MK
Type
S22T
No current signal · last broadcast 13d ago
Flights observed
148
Distinct callsigns
2
Country
US
Last broadcast
13d ago

Last known position

Most recent position reported by Mode-S A1F4B1.

Country allocation

The ICAO 24-bit address A1F4B1 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 2 distinct

Callsign Airline Flights Last seen
N225MK - 147 2026-06-30
N20 0C - 1 2026-05-21

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-30 N225MK - Jun 30, 13:05 UTCJun 30, 13:45 UTC40m
2026-06-30 N225MK - Jun 30, 12:15 UTCJun 30, 12:30 UTC15m
2026-06-30 N225MK - Jun 30, 10:50 UTCJun 30, 11:05 UTC15m
2026-06-29 N225MK - Jun 29, 23:54 UTCJun 30, 01:14 UTC1h 20m
2026-06-29 N225MK - Jun 29, 13:04 UTCJun 29, 13:44 UTC40m
2026-06-29 N225MK - Jun 29, 12:00 UTCJun 29, 12:29 UTC30m
2026-06-26 N225MK - Jun 26, 01:54 UTCJun 26, 02:24 UTC30m
2026-06-25 N225MK - Jun 25, 21:05 UTCJun 25, 21:40 UTC35m
2026-06-25 N225MK - Jun 25, 19:39 UTCJun 25, 20:25 UTC45m
2026-06-25 N225MK - Jun 25, 18:15 UTCJun 25, 19:09 UTC55m
2026-06-25 N225MK - Jun 25, 17:14 UTCJun 25, 17:44 UTC30m
2026-06-25 N225MK - Jun 25, 15:54 UTCJun 25, 16:20 UTC25m
2026-06-25 N225MK - Jun 25, 13:05 UTCJun 25, 13:50 UTC45m
2026-06-25 N225MK - Jun 25, 11:15 UTCJun 25, 11:25 UTC10m
2026-06-25 N225MK - Jun 25, 01:09 UTCJun 25, 03:29 UTC2h 20m
2026-06-24 N225MK - Jun 24, 20:40 UTCJun 24, 22:14 UTC1h 35m
2026-06-24 N225MK - Jun 24, 13:14 UTCJun 24, 14:04 UTC50m
2026-06-24 N225MK - Jun 24, 10:45 UTCJun 24, 10:59 UTC15m
2026-06-24 N225MK - Jun 24, 09:09 UTCJun 24, 09:24 UTC15m
2026-06-23 N225MK - Jun 23, 23:34 UTCJun 24, 00:25 UTC50m
2026-06-23 N225MK - Jun 23, 16:09 UTCJun 23, 16:59 UTC50m
2026-06-23 N225MK - Jun 23, 14:15 UTCJun 23, 15:19 UTC1h 5m
2026-06-23 N225MK - Jun 23, 11:45 UTCJun 23, 12:05 UTC20m
2026-06-23 N225MK - Jun 23, 11:04 UTCJun 23, 11:14 UTC10m
2026-06-23 N225MK - Jun 23, 00:30 UTCJun 23, 01:45 UTC1h 15m
2026-06-22 N225MK ORL → ORL Jun 22, 19:44 UTCJun 22, 21:14 UTC1h 30m
2026-06-22 N225MK - Jun 22, 16:34 UTCJun 22, 16:45 UTC10m
2026-06-21 N225MK - Jun 21, 18:00 UTCJun 21, 18:25 UTC25m
2026-06-21 N225MK - Jun 21, 15:25 UTCJun 21, 17:29 UTC2h 5m
2026-06-21 N225MK - Jun 21, 13:04 UTCJun 21, 14:40 UTC1h 35m
2026-06-19 N225MK - Jun 19, 19:09 UTCJun 19, 21:30 UTC2h 20m
2026-06-19 N225MK - Jun 19, 15:54 UTCJun 19, 18:30 UTC2h 35m
2026-06-19 N225MK - Jun 19, 14:19 UTCJun 19, 14:59 UTC40m
2026-06-18 N225MK TPA → ORL Jun 18, 22:55 UTCJun 18, 23:30 UTC35m
2026-06-18 N225MK - Jun 18, 21:35 UTCJun 18, 22:45 UTC1h 10m
2026-06-18 N225MK - Jun 18, 11:35 UTCJun 18, 12:30 UTC55m
2026-06-18 N225MK - Jun 18, 10:15 UTCJun 18, 10:45 UTC30m
2026-06-17 N225MK - Jun 17, 19:35 UTCJun 18, 01:30 UTC5h 55m
2026-06-17 N225MK - Jun 17, 18:10 UTCJun 17, 18:50 UTC40m
2026-06-17 N225MK - Jun 17, 00:40 UTCJun 17, 01:35 UTC55m
2026-06-16 N225MK ORL → SRQ Jun 16, 16:25 UTCJun 16, 17:05 UTC40m
2026-06-16 N225MK - Jun 16, 12:20 UTCJun 16, 12:50 UTC30m
2026-06-16 N225MK ORL → CLW Jun 16, 11:10 UTCJun 16, 11:49 UTC40m
2026-06-15 N225MK - Jun 15, 21:09 UTCJun 15, 21:35 UTC25m
2026-06-15 N225MK - Jun 15, 20:00 UTCJun 15, 20:34 UTC35m
2026-06-12 N225MK - Jun 12, 19:30 UTCJun 12, 19:55 UTC25m
2026-06-11 N225MK - Jun 11, 19:55 UTCJun 11, 20:40 UTC45m
2026-06-11 N225MK - Jun 11, 13:45 UTCJun 11, 14:15 UTC30m
2026-06-11 N225MK - Jun 11, 01:25 UTCJun 11, 01:55 UTC30m
2026-06-11 N225MK VNC → CLW Jun 11, 00:25 UTCJun 11, 00:50 UTC25m

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 N225MK page for operator, model, and routing details .

Mode-S A1F4B1 frequently asked

What is Mode-S code A1F4B1?
A1F4B1 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N225MK.
Where is Mode-S A1F4B1 registered?
Mode-S code A1F4B1 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 A1F4B1 broadcasting right now?
No active broadcast right now. Last signal was 13d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1F4B1, octal 50372261, decimal 10,613,937.
What flights does A1F4B1 operate?
Mode-S A1F4B1 has broadcast 2 distinct callsigns, including N225MK, N20 0C.