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sensors Mode-S transponder

A121E6

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N172PF · CESSNA 172 Skyhawk · operated by MILLARD RICHARD A

Hex
A121E6
Octal
50220746
Decimal
10,559,974
Country
US
Tail
N172PF
Type
C172
No current signal · last broadcast Jul 4, 19:15 UTC
Flights observed
33
Distinct callsigns
1
Country
US
Last broadcast
Jul 4, 19:15 UTC

Last known position

Most recent position reported by Mode-S A121E6.

Country allocation

The ICAO 24-bit address A121E6 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
N172PF - 33 2026-07-04

Recent flights last 33

DateFlightRouteTakeoffLandingDuration
2026-07-04 N172PF - Jul 4, 18:40 UTCJul 4, 19:15 UTC35m
2026-07-04 N172PF - Jul 4, 15:15 UTCJul 4, 16:30 UTC1h 15m
2026-06-28 N172PF - Jun 28, 15:49 UTCJun 28, 16:14 UTC25m
2026-06-28 N172PF - Jun 28, 14:50 UTCJun 28, 14:59 UTC10m
2026-06-23 N172PF - Jun 23, 19:10 UTCJun 23, 19:59 UTC50m
2026-06-23 N172PF - Jun 23, 15:30 UTCJun 23, 16:24 UTC55m
2026-06-20 N172PF - Jun 20, 17:59 UTCJun 20, 18:10 UTC10m
2026-06-19 N172PF - Jun 19, 14:19 UTCJun 19, 14:29 UTC10m
2026-06-17 N172PF - Jun 17, 15:55 UTCJun 17, 16:50 UTC55m
2026-06-17 N172PF - Jun 17, 12:25 UTCJun 17, 15:00 UTC2h 35m
2026-06-15 N172PF - Jun 15, 18:55 UTCJun 15, 19:45 UTC50m
2026-06-15 N172PF - Jun 15, 17:04 UTCJun 15, 18:10 UTC1h 5m
2026-06-15 N172PF - Jun 15, 15:04 UTCJun 15, 16:30 UTC1h 25m
2026-06-13 N172PF - Jun 13, 17:45 UTCJun 13, 20:10 UTC2h 25m
2026-06-11 N172PF - Jun 11, 23:25 UTCJun 12, 00:25 UTC1h 0m
2026-06-11 N172PF - Jun 11, 21:50 UTCJun 11, 22:15 UTC25m
2026-06-11 N172PF - Jun 11, 19:50 UTCJun 11, 20:35 UTC45m
2026-06-11 N172PF - Jun 11, 15:10 UTCJun 11, 15:20 UTC10m
2026-06-10 N172PF - Jun 10, 13:50 UTCJun 10, 14:05 UTC15m
2026-06-06 N172PF - Jun 6, 15:54 UTCJun 6, 16:14 UTC20m
2026-06-05 N172PF - Jun 5, 14:25 UTCJun 5, 15:35 UTC1h 10m
2026-06-05 N172PF - Jun 5, 13:30 UTCJun 5, 13:50 UTC20m
2026-06-05 N172PF - Jun 5, 11:40 UTCJun 5, 12:25 UTC45m
2026-06-04 N172PF - Jun 4, 19:10 UTCJun 4, 19:20 UTC10m
2026-06-04 N172PF - Jun 4, 16:10 UTCJun 4, 16:45 UTC35m
2026-06-03 N172PF - Jun 3, 14:55 UTCJun 3, 15:05 UTC10m
2026-06-03 N172PF - Jun 3, 13:20 UTCJun 3, 13:40 UTC20m
2026-06-02 N172PF - Jun 2, 15:00 UTCJun 2, 15:50 UTC50m
2026-06-02 N172PF - Jun 2, 13:00 UTCJun 2, 14:00 UTC1h 0m
2026-05-31 N172PF - May 31, 14:10 UTCMay 31, 14:25 UTC15m
2026-05-31 N172PF - May 31, 12:55 UTCMay 31, 13:05 UTC10m
2026-05-27 N172PF - May 27, 18:35 UTCMay 27, 19:25 UTC50m
2026-05-20 N172PF - May 20, 21:25 UTCMay 20, 21:45 UTC20m

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 N172PF page for operator, model, and routing details .

Mode-S A121E6 frequently asked

What is Mode-S code A121E6?
A121E6 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N172PF.
Where is Mode-S A121E6 registered?
Mode-S code A121E6 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 A121E6 broadcasting right now?
No active broadcast right now. Last signal was Jul 4, 19:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A121E6, octal 50220746, decimal 10,559,974.
What flights does A121E6 operate?
Mode-S A121E6 has broadcast 1 distinct callsign, including N172PF.