Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1CFC2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N21591 · CESSNA 172 Skyhawk · operated by KOHN AVIATION LLC

Hex
A1CFC2
Octal
50347702
Decimal
10,604,482
Country
US
Tail
N21591
Type
C172
No current signal · last broadcast 1h ago
Flights observed
103
Distinct callsigns
1
Country
US
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S A1CFC2.

Country allocation

The ICAO 24-bit address A1CFC2 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
BYF21 - 103 2026-06-02

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-02 BYF21 SQL → SQL Jun 2, 23:10 UTCJun 2, 23:55 UTC45m
2026-06-02 BYF21 SQL → SQL Jun 2, 18:10 UTCJun 2, 19:15 UTC1h 5m
2026-06-02 BYF21 SQL → SQL Jun 2, 16:50 UTCJun 2, 17:00 UTC10m
2026-06-01 BYF21 SQL → SQL Jun 1, 22:40 UTCJun 1, 23:45 UTC1h 5m
2026-06-01 BYF21 - Jun 1, 20:05 UTCJun 1, 21:05 UTC1h 0m
2026-06-01 BYF21 - Jun 1, 18:00 UTCJun 1, 18:35 UTC35m
2026-06-01 BYF21 SQL → SQL Jun 1, 15:25 UTCJun 1, 15:40 UTC15m
2026-05-31 BYF21 SQL → SQL May 31, 19:50 UTCMay 31, 21:35 UTC1h 45m
2026-05-31 BYF21 SQL → SQL May 31, 18:00 UTCMay 31, 18:35 UTC35m
2026-05-30 BYF21 SQL → SQL May 30, 23:45 UTCMay 30, 23:55 UTC10m
2026-05-30 BYF21 - May 30, 23:05 UTCMay 30, 23:40 UTC35m
2026-05-30 BYF21 SQL → SQL May 30, 20:40 UTCMay 30, 21:55 UTC1h 15m
2026-05-30 BYF21 - May 30, 18:55 UTCMay 30, 19:40 UTC45m
2026-05-29 BYF21 SQL → SQL May 29, 22:10 UTCMay 29, 23:00 UTC50m
2026-05-29 BYF21 - May 29, 16:40 UTCMay 29, 17:00 UTC20m
2026-05-29 BYF21 SQL → SQL May 29, 16:10 UTCMay 29, 16:35 UTC25m
2026-05-27 BYF21 - May 27, 18:10 UTCMay 27, 18:30 UTC20m
2026-05-27 BYF21 - May 27, 17:40 UTCMay 27, 18:05 UTC25m
2026-05-24 BYF21 SQL → SQL May 24, 18:45 UTCMay 24, 19:20 UTC35m
2026-05-24 BYF21 SQL → SQL May 24, 17:10 UTCMay 24, 17:35 UTC25m
2026-05-24 BYF21 SQL → SQL May 24, 00:25 UTCMay 24, 01:20 UTC55m
2026-05-23 BYF21 SQL → SQL May 23, 20:05 UTCMay 23, 20:20 UTC15m
2026-05-23 BYF21 SQL → SQL May 23, 19:55 UTCMay 23, 20:00 UTC5m
2026-05-23 BYF21 - May 23, 00:25 UTCMay 23, 01:10 UTC45m
2026-05-22 BYF21 SQL → SQL May 22, 22:30 UTCMay 22, 23:20 UTC50m
2026-05-22 BYF21 - May 22, 19:50 UTCMay 22, 20:25 UTC35m
2026-05-22 BYF21 SQL → SQL May 22, 18:10 UTCMay 22, 18:35 UTC25m
2026-05-22 BYF21 SQL → SQL May 22, 01:05 UTCMay 22, 02:05 UTC1h 0m
2026-05-21 BYF21 - May 21, 21:00 UTCMay 21, 22:05 UTC1h 5m
2026-05-21 BYF21 - May 21, 18:15 UTCMay 21, 18:50 UTC35m
2026-05-20 BYF21 - May 20, 21:55 UTCMay 20, 23:20 UTC1h 25m
2026-05-19 BYF21 - May 19, 20:20 UTCMay 19, 21:30 UTC1h 10m
2026-05-19 BYF21 SQL → SQL May 19, 17:15 UTCMay 19, 17:35 UTC20m
2026-05-19 BYF21 SQL → SQL May 19, 16:55 UTCMay 19, 17:10 UTC15m
2026-05-18 BYF21 - May 18, 22:55 UTCMay 18, 23:10 UTC15m
2026-05-17 BYF21 - May 17, 23:15 UTCMay 18, 00:00 UTC45m
2026-05-17 BYF21 SQL → SQL May 17, 20:30 UTCMay 17, 20:45 UTC15m
2026-05-17 BYF21 SQL → SQL May 17, 20:15 UTCMay 17, 20:25 UTC10m
2026-05-17 BYF21 - May 17, 18:01 UTCMay 17, 18:35 UTC35m
2026-05-17 BYF21 - May 17, 17:20 UTCMay 17, 17:30 UTC10m
2026-05-16 BYF21 SQL → SQL May 16, 21:50 UTCMay 16, 22:35 UTC45m
2026-05-16 BYF21 - May 16, 18:00 UTCMay 16, 18:55 UTC55m
2026-05-16 BYF21 - May 16, 00:10 UTCMay 16, 01:25 UTC1h 15m
2026-05-15 BYF21 SQL → SQL May 15, 21:25 UTCMay 15, 22:10 UTC45m
2026-05-15 BYF21 SQL → SQL May 15, 17:35 UTCMay 15, 17:40 UTC5m
2026-05-15 BYF21 SQL → SQL May 15, 00:00 UTCMay 15, 00:55 UTC55m
2026-05-13 BYF21 - May 13, 18:40 UTCMay 13, 19:50 UTC1h 10m
2026-05-12 BYF21 - May 12, 21:45 UTCMay 12, 22:15 UTC30m
2026-05-12 BYF21 SQL → SQL May 12, 19:45 UTCMay 12, 20:25 UTC40m
2026-05-12 BYF21 SQL → SQL May 12, 19:10 UTCMay 12, 19:40 UTC30m

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 N21591 page for operator, model, and routing details .

Mode-S A1CFC2 frequently asked

What is Mode-S code A1CFC2?
A1CFC2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N21591.
Where is Mode-S A1CFC2 registered?
Mode-S code A1CFC2 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 A1CFC2 broadcasting right now?
No active broadcast right now. Last signal was 1h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1CFC2, octal 50347702, decimal 10,604,482.
What flights does A1CFC2 operate?
Mode-S A1CFC2 has broadcast 1 distinct callsign, including BYF21.