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sensors Mode-S transponder

A1221C

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N172RK · CESSNA 172 Skyhawk · operated by EUROS AIRCRAFT LEASING LLC

Hex
A1221C
Octal
50221034
Decimal
10,560,028
Country
US
Tail
N172RK
Type
C172
No current signal · last broadcast 6h ago
Flights observed
185
Distinct callsigns
1
Country
US
Last broadcast
6h ago

Last known position

Most recent position reported by Mode-S A1221C.

Country allocation

The ICAO 24-bit address A1221C 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
N172RK - 185 2026-07-22

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-22 N172RK CLL → CLL Jul 22, 00:25 UTCJul 22, 01:40 UTC1h 15m
2026-07-21 N172RK CLL → CLL Jul 21, 18:45 UTCJul 21, 20:05 UTC1h 20m
2026-07-21 N172RK CLL → CLL Jul 21, 13:40 UTCJul 21, 14:55 UTC1h 15m
2026-07-20 N172RK CLL → CLL Jul 20, 19:00 UTCJul 21, 00:10 UTC5h 9m
2026-07-20 N172RK - Jul 20, 15:45 UTCJul 20, 17:35 UTC1h 50m
2026-07-20 N172RK - Jul 20, 01:00 UTCJul 20, 01:55 UTC55m
2026-07-19 N172RK - Jul 19, 20:40 UTCJul 19, 21:40 UTC1h 0m
2026-07-18 N172RK CLL → CLL Jul 18, 20:55 UTCJul 18, 22:40 UTC1h 45m
2026-07-18 N172RK - Jul 18, 18:00 UTCJul 18, 19:50 UTC1h 50m
2026-07-18 N172RK CLL → CLL Jul 18, 00:29 UTCJul 18, 02:05 UTC1h 35m
2026-07-17 N172RK - Jul 17, 22:29 UTCJul 17, 23:10 UTC40m
2026-07-17 N172RK CLL → CLL Jul 17, 20:15 UTCJul 17, 20:50 UTC35m
2026-07-17 N172RK - Jul 17, 19:30 UTCJul 17, 20:10 UTC40m
2026-07-16 N172RK - Jul 16, 16:05 UTCJul 16, 17:05 UTC1h 0m
2026-07-16 N172RK CLL → CLL Jul 16, 02:15 UTCJul 16, 04:15 UTC2h 0m
2026-07-16 N172RK - Jul 16, 00:10 UTCJul 16, 01:15 UTC1h 5m
2026-07-15 N172RK - Jul 15, 21:55 UTCJul 15, 23:10 UTC1h 15m
2026-07-13 N172RK - Jul 13, 15:45 UTCJul 13, 17:20 UTC1h 35m
2026-07-12 N172RK - Jul 12, 20:20 UTCJul 12, 20:40 UTC20m
2026-07-10 N172RK - Jul 10, 17:15 UTCJul 10, 17:25 UTC10m
2026-07-10 N172RK - Jul 10, 16:10 UTCJul 10, 16:20 UTC10m
2026-07-10 N172RK CLL → CLL Jul 10, 13:50 UTCJul 10, 14:55 UTC1h 5m
2026-07-10 N172RK - Jul 10, 01:35 UTCJul 10, 02:20 UTC45m
2026-07-09 N172RK - Jul 9, 23:00 UTCJul 10, 00:45 UTC1h 45m
2026-07-09 N172RK - Jul 9, 21:30 UTCJul 9, 22:30 UTC1h 0m
2026-07-09 N172RK - Jul 9, 19:45 UTCJul 9, 20:55 UTC1h 10m
2026-07-09 N172RK - Jul 9, 18:00 UTCJul 9, 18:55 UTC55m
2026-07-09 N172RK - Jul 9, 16:40 UTCJul 9, 16:55 UTC15m
2026-07-09 N172RK - Jul 9, 15:45 UTCJul 9, 16:00 UTC15m
2026-07-09 N172RK - Jul 9, 13:55 UTCJul 9, 14:10 UTC15m
2026-07-09 N172RK - Jul 9, 02:00 UTCJul 9, 02:25 UTC25m
2026-07-09 N172RK - Jul 9, 00:00 UTCJul 9, 01:10 UTC1h 10m
2026-07-08 N172RK - Jul 8, 21:25 UTCJul 8, 22:40 UTC1h 15m
2026-07-08 N172RK - Jul 8, 18:05 UTCJul 8, 18:40 UTC35m
2026-07-07 N172RK - Jul 7, 18:50 UTCJul 7, 19:45 UTC55m
2026-07-07 N172RK CLL → CLL Jul 7, 15:50 UTCJul 7, 16:30 UTC40m
2026-07-05 N172RK - Jul 5, 22:30 UTCJul 6, 00:35 UTC2h 5m
2026-07-05 N172RK - Jul 5, 18:15 UTCJul 5, 20:10 UTC1h 55m
2026-07-03 N172RK - Jul 3, 23:55 UTCJul 4, 01:05 UTC1h 10m
2026-07-03 N172RK - Jul 3, 22:55 UTCJul 3, 23:05 UTC10m
2026-07-03 N172RK - Jul 3, 18:50 UTCJul 3, 20:15 UTC1h 25m
2026-07-03 N172RK - Jul 3, 02:45 UTCJul 3, 03:30 UTC45m
2026-07-02 N172RK - Jul 2, 18:55 UTCJul 2, 20:00 UTC1h 5m
2026-07-02 N172RK - Jul 2, 05:25 UTCJul 2, 06:25 UTC1h 0m
2026-07-02 N172RK - Jul 2, 03:35 UTCJul 2, 04:40 UTC1h 5m
2026-07-02 N172RK CLL → CLL Jul 2, 02:55 UTCJul 2, 03:05 UTC10m
2026-07-01 N172RK CLL → CLL Jul 1, 22:25 UTCJul 2, 00:35 UTC2h 10m
2026-07-01 N172RK - Jul 1, 19:45 UTCJul 1, 21:15 UTC1h 30m
2026-07-01 N172RK - Jul 1, 03:05 UTCJul 1, 03:55 UTC50m
2026-06-30 N172RK CLL → CLL Jun 30, 22:05 UTCJul 1, 00:55 UTC2h 50m

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 N172RK page for operator, model, and routing details .

Mode-S A1221C frequently asked

What is Mode-S code A1221C?
A1221C is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N172RK.
Where is Mode-S A1221C registered?
Mode-S code A1221C 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 A1221C broadcasting right now?
No active broadcast right now. Last signal was 6h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1221C, octal 50221034, decimal 10,560,028.
What flights does A1221C operate?
Mode-S A1221C has broadcast 1 distinct callsign, including N172RK.