Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A9D59A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N73251 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A9D59A
Octal
52352632
Decimal
11,130,266
Country
US
Tail
N73251
Type
B738
No current signal · last broadcast Jul 26, 20:15 UTC
Flights observed
448
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:15 UTC

Last known position

Most recent position reported by Mode-S A9D59A.

Country allocation

The ICAO 24-bit address A9D59A 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
UAL645 United Airlines 5 2026-05-17
UAL1821 - 5 2026-06-29
UAL467 United Airlines 4 2026-05-22
UAL2745 United Airlines 4 2026-07-24
UAL2742 United Airlines 4 2026-05-18
UAL2167 - 4 2026-06-23
UAL1968 United Airlines 4 2026-07-23
UAL1355 - 4 2026-07-08
UAL1217 - 4 2026-07-21
UAL1189 - 4 2026-07-06
UAL745 United Airlines 3 2026-04-18
UAL720 United Airlines 3 2026-06-03
UAL590 United Airlines 3 2026-06-13
UAL478 United Airlines 3 2026-05-17
UAL431 United Airlines 3 2026-07-25
UAL286 United Airlines 3 2026-04-24
UAL2821 - 3 2026-06-30
UAL2652 - 3 2026-07-07
UAL2470 - 3 2026-06-21
UAL2418 - 3 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1140 LAX → IAD Jul 26, 16:05 UTCJul 26, 20:05 UTC4h 0m
2026-07-26 UAL655 DEN → LAS Jul 26, 01:55 UTCJul 26, 03:25 UTC1h 30m
2026-07-25 UAL453 LAX → SFO Jul 25, 20:45 UTCJul 26, 00:00 UTC3h 15m
2026-07-25 UAL453 LAX → SFO Jul 25, 20:32 UTCJul 26, 00:03 UTC3h 31m
2026-07-25 UAL1909 LAS → EWR Jul 25, 16:10 UTCJul 25, 18:50 UTC2h 40m
2026-07-25 UAL1877 IAH → EWR Jul 25, 13:50 UTCJul 25, 14:15 UTC25m
2026-07-25 UAL431 BDL → IAD Jul 25, 02:05 UTCJul 25, 02:20 UTC15m
2026-07-24 UAL295 DEN → GEG Jul 24, 20:50 UTCJul 24, 22:00 UTC1h 10m
2026-07-24 UAL586 DEN → MCI Jul 24, 15:55 UTCJul 24, 18:05 UTC2h 10m
2026-07-24 UAL2745 HNL → SFO Jul 24, 02:50 UTCJul 24, 04:55 UTC2h 5m
2026-07-23 UAL1483 LAS → SFO Jul 23, 22:08 UTCJul 24, 00:38 UTC2h 30m
2026-07-23 UAL1483 LAS → SFO Jul 23, 22:15 UTCJul 24, 00:30 UTC2h 15m
2026-07-23 UAL2000 LGA → IAH Jul 23, 19:45 UTCJul 23, 20:35 UTC50m
2026-07-23 UAL1968 ORD → BOS Jul 23, 14:45 UTCJul 23, 17:45 UTC3h 0m
2026-07-23 UAL720C DEN → YYC Jul 23, 01:35 UTCJul 23, 03:35 UTC2h 0m
2026-07-23 UAL720C DEN → YYC Jul 23, 01:36 UTCJul 23, 03:37 UTC2h 1m
2026-07-22 UAL2085 EWR → AUS Jul 22, 21:45 UTCJul 22, 23:59 UTC2h 14m
2026-07-22 UAL2085 EWR → AUS Jul 22, 21:35 UTCJul 23, 00:00 UTC2h 25m
2026-07-22 UAL2051 SFO → YVR Jul 22, 18:10 UTCJul 22, 19:50 UTC1h 40m
2026-07-22 UAL1954 RDM → SFO Jul 22, 16:10 UTCJul 22, 16:35 UTC25m
2026-07-21 UAL1208 IAH → EWR Jul 21, 22:35 UTCJul 22, 00:40 UTC2h 5m
2026-07-21 UAL1396 RSW → EWR Jul 21, 19:40 UTCJul 21, 20:25 UTC45m
2026-07-21 UAL1217 DEN → DRO Jul 21, 17:37 UTCJul 21, 18:14 UTC37m
2026-07-21 UAL1217 - Jul 21, 17:30 UTCJul 21, 18:05 UTC35m
2026-07-21 UAL1424 OKC → DEN Jul 21, 14:35 UTCJul 21, 15:50 UTC1h 15m
2026-07-21 UAL1184 IAH → MSY Jul 21, 00:11 UTCJul 21, 01:29 UTC1h 18m
2026-07-21 UAL1184 IAH → MSY Jul 21, 00:20 UTCJul 21, 01:25 UTC1h 5m
2026-07-20 UAL1843 SFO → ORD Jul 20, 21:10 UTCJul 20, 22:55 UTC1h 45m
2026-07-20 UAL1294 DEN → YEG Jul 20, 17:50 UTCJul 20, 19:20 UTC1h 30m
2026-07-20 UAL318 EWR → DEN Jul 20, 12:15 UTCJul 20, 15:35 UTC3h 20m
2026-07-19 UAL2348 DEN → RSW Jul 19, 22:15 UTCJul 20, 01:40 UTC3h 25m
2026-07-19 UAL1396 RSW → EWR Jul 19, 19:45 UTCJul 19, 20:30 UTC45m
2026-07-19 UAL1217 - Jul 19, 17:40 UTCJul 19, 18:05 UTC25m
2026-07-19 UAL1217 DEN → DRO Jul 19, 17:37 UTCJul 19, 18:20 UTC43m
2026-07-19 UAL1424 OKC → DEN Jul 19, 14:35 UTCJul 19, 15:45 UTC1h 10m
2026-07-19 UAL1184 IAH → MSY Jul 19, 00:15 UTCJul 19, 01:25 UTC1h 10m
2026-07-18 UAL1953 YYC → DEN Jul 18, 19:50 UTCJul 18, 21:50 UTC2h 0m
2026-07-18 UAL1832 CUN → IAH Jul 18, 13:45 UTCJul 18, 18:05 UTC4h 20m
2026-07-17 UAL2382 IAH → PHL Jul 17, 23:30 UTCJul 18, 03:45 UTC4h 16m
2026-07-17 UAL1799 MIA → EWR Jul 17, 16:10 UTCJul 17, 18:50 UTC2h 40m
2026-07-17 UAL2371 DFW → SFO Jul 17, 11:30 UTCJul 17, 14:24 UTC2h 55m
2026-07-17 UAL1655 - Jul 17, 01:35 UTCJul 17, 03:10 UTC1h 35m
2026-07-16 UAL329 - Jul 16, 21:05 UTCJul 16, 23:05 UTC2h 0m
2026-07-16 UAL2418 DEN → BTV Jul 16, 16:15 UTCJul 16, 19:30 UTC3h 15m
2026-07-15 UAL1915 DEN → DEN Jul 15, 15:56 UTCJul 15, 16:21 UTC25m
2026-07-15 UAL1915 DEN → DEN Jul 15, 15:45 UTCJul 15, 16:25 UTC40m
2026-07-15 UAL596 LAS → DEN Jul 15, 12:30 UTCJul 15, 14:00 UTC1h 30m
2026-07-15 UAL596 LAS → DEN Jul 15, 12:44 UTCJul 15, 13:56 UTC1h 12m
2026-07-15 UAL1546 LAX → LAS Jul 15, 06:25 UTCJul 15, 07:10 UTC45m
2026-07-15 UAL2282 - Jul 15, 03:45 UTCJul 15, 04:30 UTC45m

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 N73251 page for operator, model, and routing details .

Mode-S A9D59A frequently asked

What is Mode-S code A9D59A?
A9D59A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N73251.
Where is Mode-S A9D59A registered?
Mode-S code A9D59A 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 A9D59A broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A9D59A, octal 52352632, decimal 11,130,266.
What flights does A9D59A operate?
Mode-S A9D59A has broadcast 20 distinct callsigns, including UAL645, UAL1821, UAL467, UAL2745, UAL2742.