Apparatus

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sensors Mode-S transponder

A23A03

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N24212 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A23A03
Octal
50435003
Decimal
10,631,683
Country
US
Tail
N24212
Type
B738
No current signal · last broadcast Jul 26, 21:50 UTC
Flights observed
477
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:50 UTC

Last known position

Most recent position reported by Mode-S A23A03.

Country allocation

The ICAO 24-bit address A23A03 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
UAL1748 United Airlines 6 2026-07-24
UAL551 - 5 2026-07-04
UAL2745 - 5 2026-07-15
UAL2160 United Airlines 5 2026-05-26
UAL1795 United Airlines 5 2026-06-07
UAL1303 United Airlines 5 2026-06-21
UAL719 - 4 2026-07-16
UAL578 United Airlines 4 2026-05-20
UAL467 - 4 2026-06-29
UAL453 United Airlines 4 2026-07-22
UAL2674 - 4 2026-07-19
UAL2319 - 4 2026-06-29
UAL2135 United Airlines 4 2026-06-01
UAL1854 United Airlines 4 2026-05-07
UAL1696 United Airlines 4 2026-06-09
UAL1401 United Airlines 4 2026-06-02
UAL1241 - 4 2026-07-01
UAL1048 United Airlines 4 2026-06-13
UAL8188 United Airlines 3 2026-05-19
UAL715 United Airlines 3 2026-04-27

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL372 HNL → SFO Jul 26, 20:45 UTCJul 26, 21:50 UTC1h 5m
2026-07-26 UAL2487 RSW → EWR Jul 26, 17:20 UTCJul 26, 18:15 UTC55m
2026-07-26 UAL1481 EWR → CLT Jul 26, 14:30 UTCJul 26, 15:55 UTC1h 25m
2026-07-26 UAL2433 JAX → EWR Jul 26, 01:05 UTCJul 26, 05:00 UTC3h 55m
2026-07-26 UAL2433 JAX → EWR Jul 26, 01:04 UTCJul 26, 04:55 UTC3h 51m
2026-07-25 UAL2466 SJC → DEN Jul 25, 22:00 UTCJul 25, 23:50 UTC1h 50m
2026-07-25 UAL2199 LGA → DEN Jul 25, 18:40 UTCJul 25, 20:35 UTC1h 55m
2026-07-25 UAL669 EWR → AUS Jul 25, 15:40 UTCJul 25, 17:15 UTC1h 35m
2026-07-25 UAL2771 HNL → ORD Jul 25, 12:25 UTCJul 25, 13:55 UTC1h 30m
2026-07-24 UAL1748 IAH → JAX Jul 24, 23:45 UTCJul 25, 01:10 UTC1h 25m
2026-07-24 UAL1325 DEN → PDX Jul 24, 19:50 UTCJul 24, 21:25 UTC1h 35m
2026-07-24 UAL2668 OMA → ORD Jul 24, 16:55 UTCJul 24, 18:30 UTC1h 35m
2026-07-24 UAL763 YYZ → ORD Jul 24, 13:57 UTCJul 24, 15:01 UTC1h 4m
2026-07-24 UAL763 - Jul 24, 13:55 UTCJul 24, 14:45 UTC50m
2026-07-24 UAL436 SFO → BWI Jul 24, 08:09 UTCJul 24, 12:19 UTC4h 10m
2026-07-24 UAL436 SFO → BWI Jul 24, 08:10 UTCJul 24, 12:25 UTC4h 15m
2026-07-24 UAL1267 EWR → ANC Jul 24, 05:25 UTCJul 24, 06:25 UTC1h 0m
2026-07-24 UAL2338 PSP → SFO Jul 24, 00:05 UTCJul 24, 01:35 UTC1h 30m
2026-07-23 UAL302 - Jul 23, 19:45 UTCJul 23, 22:25 UTC2h 40m
2026-07-23 UAL1915 SAN → SFO Jul 23, 15:55 UTCJul 23, 18:15 UTC2h 20m
2026-07-22 UAL453 LAX → SFO Jul 22, 20:25 UTCJul 22, 23:55 UTC3h 30m
2026-07-22 UAL453 LAX → SFO Jul 22, 20:32 UTCJul 22, 23:51 UTC3h 19m
2026-07-22 UAL1909 LAS → EWR Jul 22, 16:00 UTCJul 22, 18:50 UTC2h 50m
2026-07-22 UAL1234 EWR → ORD Jul 22, 12:15 UTCJul 22, 14:00 UTC1h 45m
2026-07-22 UAL778 DEN → BZN Jul 22, 03:55 UTCJul 22, 05:25 UTC1h 30m
2026-07-21 UAL475 EWR → MCO Jul 21, 21:30 UTCJul 21, 23:40 UTC2h 10m
2026-07-21 UAL475 EWR → MCO Jul 21, 21:30 UTCJul 21, 23:40 UTC2h 10m
2026-07-21 UAL1029 LAX → DEN Jul 21, 17:40 UTCJul 21, 19:50 UTC2h 10m
2026-07-21 UAL644 LAX → EWR Jul 21, 14:10 UTCJul 21, 15:40 UTC1h 30m
2026-07-21 UAL1565 SFO → PHX Jul 21, 01:15 UTCJul 21, 02:45 UTC1h 30m
2026-07-20 UAL517 - Jul 20, 19:40 UTCJul 20, 23:25 UTC3h 45m
2026-07-20 UAL786 - Jul 20, 16:25 UTCJul 20, 18:05 UTC1h 40m
2026-07-20 UAL623 LGA → ORD Jul 20, 12:26 UTCJul 20, 14:01 UTC1h 35m
2026-07-20 UAL623 LGA → ORD Jul 20, 12:20 UTCJul 20, 14:20 UTC2h 0m
2026-07-20 UAL2783 SFO → GUM Jul 20, 00:10 UTCJul 20, 03:20 UTC3h 10m
2026-07-19 UAL2674 - Jul 19, 18:45 UTCJul 19, 22:00 UTC3h 15m
2026-07-19 UAL2133 EWR → RSW Jul 19, 13:35 UTCJul 19, 16:40 UTC3h 5m
2026-07-19 UAL2419 - Jul 19, 03:00 UTCJul 19, 04:55 UTC1h 55m
2026-07-18 UAL2108 EWR → CHS Jul 18, 23:55 UTCJul 19, 00:45 UTC50m
2026-07-18 UAL2108 EWR → CHS Jul 18, 23:46 UTCJul 19, 01:24 UTC1h 38m
2026-07-18 UAL2156 IAD → LAS Jul 18, 17:45 UTCJul 18, 22:05 UTC4h 20m
2026-07-18 UAL204 ABQ → IAD Jul 18, 12:55 UTCJul 18, 16:15 UTC3h 20m
2026-07-18 UAL1381 - Jul 18, 02:00 UTCJul 18, 03:35 UTC1h 36m
2026-07-17 UAL2323 - Jul 17, 23:10 UTCJul 17, 23:50 UTC40m
2026-07-17 UAL1022 - Jul 17, 20:10 UTCJul 17, 22:05 UTC1h 55m
2026-07-17 UAL1191 BUR → DEN Jul 17, 16:19 UTCJul 17, 18:15 UTC1h 55m
2026-07-17 UAL2411 DEN → BUR Jul 17, 01:55 UTCJul 17, 03:45 UTC1h 50m
2026-07-16 UAL719 SJC → DEN Jul 16, 21:40 UTCJul 16, 23:49 UTC2h 10m
2026-07-16 UAL2808 DEN → SJC Jul 16, 18:22 UTCJul 16, 20:16 UTC1h 54m
2026-07-16 UAL2808 DEN → SJC Jul 16, 18:15 UTCJul 16, 20:25 UTC2h 10m

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 N24212 page for operator, model, and routing details .

Mode-S A23A03 frequently asked

What is Mode-S code A23A03?
A23A03 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N24212.
Where is Mode-S A23A03 registered?
Mode-S code A23A03 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 A23A03 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:50 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A23A03, octal 50435003, decimal 10,631,683.
What flights does A23A03 operate?
Mode-S A23A03 has broadcast 20 distinct callsigns, including UAL1748, UAL551, UAL2745, UAL2160, UAL1795.