Apparatus

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sensors Mode-S transponder

AB4531

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N825UA · AIRBUS A-319 · operated by UNITED AIRLINES INC

Hex
AB4531
Octal
52642461
Decimal
11,224,369
Country
US
Tail
N825UA
Type
A319
No current signal · last broadcast Jul 26, 22:05 UTC
Flights observed
371
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:05 UTC

Last known position

Most recent position reported by Mode-S AB4531.

Country allocation

The ICAO 24-bit address AB4531 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
UAL2718 - 11 2026-07-14
UAL1334 - 9 2026-07-14
UAL2836 - 6 2026-07-14
UAL1090 United Airlines 6 2026-06-03
UAL737 - 5 2026-07-11
UAL616 United Airlines 5 2026-07-18
UAL283 United Airlines 5 2026-07-25
UAL1963 - 5 2026-07-18
UAL1846 - 5 2026-07-04
UAL538 - 4 2026-07-11
UAL436 - 4 2026-07-13
UAL2468 United Airlines 4 2026-07-26
UAL1642 - 4 2026-07-11
UAL1367 - 4 2026-07-10
UAL1235 - 4 2026-06-24
UAL773 - 3 2026-06-22
UAL648 United Airlines 3 2026-07-21
UAL568 - 3 2026-07-02
UAL544 United Airlines 3 2026-05-17
UAL487 United Airlines 3 2026-07-21

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL313 BOI → SFO Jul 26, 21:20 UTCJul 26, 22:05 UTC45m
2026-07-26 UAL2468 TPA → EWR Jul 26, 17:15 UTCJul 26, 19:45 UTC2h 30m
2026-07-26 UAL2233 SNA → EWR Jul 26, 11:40 UTCJul 26, 15:15 UTC3h 35m
2026-07-26 UAL2198 IAH → BDL Jul 26, 03:05 UTCJul 26, 03:35 UTC30m
2026-07-25 UAL283 DFW → EWR Jul 25, 23:05 UTCJul 26, 01:20 UTC2h 15m
2026-07-25 UAL732 DEN → CVG Jul 25, 20:00 UTCJul 25, 21:30 UTC1h 30m
2026-07-25 UAL347 PHL → DEN Jul 25, 16:10 UTCJul 25, 17:50 UTC1h 40m
2026-07-25 UAL2852 EWR → DEN Jul 25, 06:10 UTCJul 25, 08:00 UTC1h 50m
2026-07-24 UAL1841 SFO → IAH Jul 24, 01:45 UTCJul 24, 03:45 UTC2h 0m
2026-07-23 UAL1208 IAH → EWR Jul 23, 22:20 UTCJul 24, 00:20 UTC2h 0m
2026-07-23 UAL1541 IAH → LGA Jul 23, 18:05 UTCJul 23, 19:50 UTC1h 45m
2026-07-23 UAL456 EWR → SRQ Jul 23, 14:15 UTCJul 23, 16:05 UTC1h 50m
2026-07-23 UAL498 PDX → EWR Jul 23, 02:30 UTCJul 23, 04:40 UTC2h 10m
2026-07-22 UAL1112 BOS → DEN Jul 22, 17:15 UTCJul 22, 19:00 UTC1h 45m
2026-07-22 UAL1045 DEN → IAD Jul 22, 14:00 UTCJul 22, 15:30 UTC1h 30m
2026-07-22 UAL1351 FLL → EWR Jul 22, 00:20 UTCJul 22, 01:35 UTC1h 15m
2026-07-21 UAL259 DEN → MCO Jul 21, 20:00 UTCJul 21, 22:15 UTC2h 15m
2026-07-21 UAL487 PHX → SFO Jul 21, 17:56 UTCJul 21, 18:40 UTC44m
2026-07-21 UAL487 PHX → SFO Jul 21, 18:05 UTCJul 21, 18:15 UTC10m
2026-07-21 UAL1808 CHS → EWR Jul 21, 12:35 UTCJul 21, 16:00 UTC3h 25m
2026-07-21 UAL1808 CHS → EWR Jul 21, 12:18 UTCJul 21, 15:54 UTC3h 36m
2026-07-21 UAL648 EWR → SFO Jul 21, 01:26 UTCJul 21, 04:35 UTC3h 9m
2026-07-21 UAL648 EWR → SFO Jul 21, 01:30 UTCJul 21, 04:40 UTC3h 10m
2026-07-20 UAL2279 PDX → SFO Jul 20, 22:30 UTCJul 21, 00:10 UTC1h 40m
2026-07-20 UAL1301 - Jul 20, 17:55 UTCJul 20, 19:05 UTC1h 10m
2026-07-20 UAL1301 SFO → PDX Jul 20, 18:05 UTCJul 20, 19:02 UTC57m
2026-07-20 UAL1808 CHS → EWR Jul 20, 12:20 UTCJul 20, 16:05 UTC3h 45m
2026-07-19 UAL648 EWR → SFO Jul 19, 23:30 UTCJul 20, 02:35 UTC3h 5m
2026-07-19 UAL2305 RSW → ORD Jul 19, 21:35 UTCJul 19, 22:25 UTC50m
2026-07-19 UAL671 DEN → BZN Jul 19, 17:48 UTCJul 19, 19:41 UTC1h 53m
2026-07-19 UAL671 DEN → BZN Jul 19, 17:45 UTCJul 19, 19:45 UTC2h 0m
2026-07-19 UAL2383 PHL → DEN Jul 19, 12:50 UTCJul 19, 15:50 UTC3h 0m
2026-07-19 UAL2671 DEN → RDU Jul 19, 00:40 UTCJul 19, 03:50 UTC3h 10m
2026-07-18 UAL1728 SFO → IAH Jul 18, 21:45 UTCJul 18, 22:55 UTC1h 10m
2026-07-18 UAL1728 SFO → IAH Jul 18, 21:27 UTCJul 18, 22:55 UTC1h 28m
2026-07-18 UAL792 LAX → EWR Jul 18, 18:00 UTCJul 18, 19:05 UTC1h 5m
2026-07-18 UAL1963 - Jul 18, 13:20 UTCJul 18, 16:05 UTC2h 45m
2026-07-18 UAL616 SJC → ORD Jul 18, 01:00 UTCJul 18, 03:45 UTC2h 46m
2026-07-18 UAL616 SJC → ORD Jul 18, 00:59 UTCJul 18, 03:46 UTC2h 47m
2026-07-17 UAL447 SFO → SEA Jul 17, 20:50 UTCJul 17, 23:10 UTC2h 20m
2026-07-17 UAL1241 DEN → BHM Jul 17, 16:36 UTCJul 17, 19:06 UTC2h 30m
2026-07-17 UAL1241 - Jul 17, 16:40 UTCJul 17, 19:25 UTC2h 45m
2026-07-17 UAL340 SFO → DEN Jul 17, 11:50 UTCJul 17, 14:20 UTC2h 30m
2026-07-17 UAL1305 - Jul 17, 02:20 UTCJul 17, 02:50 UTC30m
2026-07-17 UAL1305 - Jul 17, 00:10 UTCJul 17, 02:15 UTC2h 5m
2026-07-16 UAL2187 BUR → DEN Jul 16, 20:09 UTCJul 16, 22:25 UTC2h 15m
2026-07-16 UAL2115 - Jul 16, 17:45 UTCJul 16, 18:40 UTC55m
2026-07-16 UAL1293 BNA → SFO Jul 16, 11:45 UTCJul 16, 15:55 UTC4h 10m
2026-07-15 UAL499 SFO → BNA Jul 15, 17:35 UTCJul 15, 21:40 UTC4h 5m
2026-07-15 UAL2177 - Jul 15, 11:00 UTCJul 15, 15:35 UTC4h 35m

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 N825UA page for operator, model, and routing details .

Mode-S AB4531 frequently asked

What is Mode-S code AB4531?
AB4531 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N825UA.
Where is Mode-S AB4531 registered?
Mode-S code AB4531 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 AB4531 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:05 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AB4531, octal 52642461, decimal 11,224,369.
What flights does AB4531 operate?
Mode-S AB4531 has broadcast 20 distinct callsigns, including UAL2718, UAL1334, UAL2836, UAL1090, UAL737.