Apparatus

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sensors Mode-S transponder

A21B19

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N253AF · PILATUS PC-12 · operated by J3B LLC, ALPACA AIR II LLC, DAVIS JUSTIN W, BISCIOTTI MICHAEL G, CLOVERLAND LLC, EQUITY AMERICAN FINANCIAL SERVICES INC

Hex
A21B19
Octal
50415431
Decimal
10,623,769
Country
US
Tail
N253AF
Type
PC12
No current signal · last broadcast Jul 26, 20:50 UTC
Flights observed
282
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:50 UTC

Last known position

Most recent position reported by Mode-S A21B19.

Country allocation

The ICAO 24-bit address A21B19 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 20 distinct

Callsign Airline Flights Last seen
N235AF - 35 2026-07-26
CNS222 - 28 2026-05-18
CNS33 - 27 2026-06-12
CNS513 - 21 2026-06-20
CNS15 - 18 2026-04-27
CNS316 - 16 2026-05-11
CNS1030 - 11 2026-06-29
CNS848 - 10 2026-07-20
CNS2112 - 10 2026-05-22
CNS310 - 9 2026-07-12
CNS1012 - 8 2026-07-03
CNS66 - 7 2026-07-25
CNS100 - 7 2026-05-13
CNS678 - 6 2026-07-23
CNS2013 - 6 2026-07-16
CNS201 - 6 2026-05-05
CNS3311 - 5 2026-07-05
CNS1824 - 5 2026-05-20
CNS17 - 5 2026-07-07
CNS130 - 5 2026-07-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 CNS1010 - Jul 26, 20:35 UTCJul 26, 20:50 UTC15m
2026-07-26 N235AF - Jul 26, 17:30 UTCJul 26, 17:45 UTC15m
2026-07-26 N235AF - Jul 26, 14:35 UTCJul 26, 15:05 UTC30m
2026-07-25 CNS66 - Jul 25, 20:10 UTCJul 25, 21:10 UTC1h 0m
2026-07-25 CNS66 - Jul 25, 16:10 UTCJul 25, 19:20 UTC3h 10m
2026-07-25 CNS66 - Jul 25, 13:35 UTCJul 25, 15:15 UTC1h 40m
2026-07-23 CNS678 - Jul 23, 20:05 UTCJul 23, 20:40 UTC35m
2026-07-23 CNS678 - Jul 23, 18:35 UTCJul 23, 19:35 UTC1h 0m
2026-07-23 CNS678 - Jul 23, 14:50 UTCJul 23, 15:35 UTC45m
2026-07-23 CNS678 - Jul 23, 13:00 UTCJul 23, 13:30 UTC30m
2026-07-23 CNS678 - Jul 23, 12:10 UTCJul 23, 12:25 UTC15m
2026-07-21 CNS75 - Jul 21, 20:25 UTCJul 21, 20:40 UTC15m
2026-07-21 CNS1 - Jul 21, 19:50 UTCJul 21, 20:05 UTC15m
2026-07-20 CNS130 - Jul 20, 20:35 UTCJul 20, 21:10 UTC35m
2026-07-20 CNS130 OCE → ALB Jul 20, 18:30 UTCJul 20, 19:50 UTC1h 20m
2026-07-20 CNS130 - Jul 20, 17:10 UTCJul 20, 17:55 UTC45m
2026-07-20 CNS130 - Jul 20, 14:20 UTCJul 20, 15:55 UTC1h 35m
2026-07-20 CNS130 - Jul 20, 12:40 UTCJul 20, 13:30 UTC50m
2026-07-20 CNS848 - Jul 20, 00:20 UTCJul 20, 00:35 UTC15m
2026-07-19 CNS848 - Jul 19, 22:20 UTCJul 19, 23:15 UTC55m
2026-07-19 CNS848 - Jul 19, 18:15 UTCJul 19, 19:10 UTC55m
2026-07-19 CNS848 - Jul 19, 14:30 UTCJul 19, 17:30 UTC3h 0m
2026-07-18 CNS848 JOT → FTY Jul 18, 20:10 UTCJul 18, 22:10 UTC2h 0m
2026-07-18 CNS848 - Jul 18, 15:50 UTCJul 18, 18:15 UTC2h 25m
2026-07-18 CNS848 - Jul 18, 13:40 UTCJul 18, 15:10 UTC1h 30m
2026-07-17 CNS848 - Jul 17, 21:00 UTCJul 17, 23:35 UTC2h 35m
2026-07-17 CNS848 - Jul 17, 17:44 UTCJul 17, 20:04 UTC2h 20m
2026-07-17 CNS848 - Jul 17, 14:55 UTCJul 17, 16:40 UTC1h 45m
2026-07-16 CNS2013 BCT → MCO Jul 16, 12:09 UTCJul 16, 17:05 UTC4h 55m
2026-07-16 CNS2013 - Jul 16, 11:10 UTCJul 16, 11:25 UTC15m
2026-07-15 CNS2013 - Jul 15, 14:45 UTCJul 15, 16:45 UTC2h 0m
2026-07-14 CNS2013 - Jul 14, 20:45 UTCJul 14, 21:40 UTC55m
2026-07-14 CNS2013 - Jul 14, 18:20 UTCJul 14, 19:20 UTC1h 0m
2026-07-14 CNS2013 - Jul 14, 15:25 UTCJul 14, 17:15 UTC1h 50m
2026-07-13 N235AF - Jul 13, 14:50 UTCJul 13, 15:15 UTC25m
2026-07-13 N235AF - Jul 13, 13:10 UTCJul 13, 13:40 UTC30m
2026-07-12 CNS310 - Jul 12, 18:35 UTCJul 12, 19:05 UTC30m
2026-07-12 CNS310 - Jul 12, 13:20 UTCJul 12, 18:01 UTC4h 40m
2026-07-11 CNS310 - Jul 11, 20:30 UTCJul 11, 21:15 UTC45m
2026-07-11 CNS310 - Jul 11, 17:15 UTCJul 11, 19:45 UTC2h 30m
2026-07-11 CNS310 - Jul 11, 00:10 UTCJul 11, 00:30 UTC20m
2026-07-10 CNS310 CLD → AVX Jul 10, 23:20 UTCJul 10, 23:40 UTC20m
2026-07-10 CNS310 - Jul 10, 21:00 UTCJul 10, 22:40 UTC1h 40m
2026-07-10 CNS310 - Jul 10, 19:35 UTCJul 10, 20:30 UTC55m
2026-07-10 CNS310 - Jul 10, 18:30 UTCJul 10, 19:00 UTC30m
2026-07-08 CNS66 - Jul 8, 14:50 UTCJul 8, 16:45 UTC1h 55m
2026-07-08 CNS66 - Jul 8, 12:55 UTCJul 8, 13:55 UTC1h 0m
2026-07-07 CNS66 - Jul 7, 22:30 UTCJul 8, 00:15 UTC1h 45m
2026-07-07 CNS66 - Jul 7, 19:05 UTCJul 7, 20:20 UTC1h 15m
2026-07-07 CNS17 - Jul 7, 16:00 UTCJul 7, 17:05 UTC1h 5m

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 N253AF page for operator, model, and routing details .

Mode-S A21B19 frequently asked

What is Mode-S code A21B19?
A21B19 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N253AF.
Where is Mode-S A21B19 registered?
Mode-S code A21B19 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 A21B19 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:50 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A21B19, octal 50415431, decimal 10,623,769.
What flights does A21B19 operate?
Mode-S A21B19 has broadcast 20 distinct callsigns, including N235AF, CNS222, CNS33, CNS513, CNS15.