Apparatus

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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
Broadcasting now · callsign UAL2449 · 25,900 ft
Flights observed
394
Distinct callsigns
20
Country
US
Last broadcast
9h ago

Current position

A9D59A is currently broadcasting. Map zoomed to live position.

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
UAL2742 United Airlines 4 2026-05-18
UAL2167 - 4 2026-06-23
UAL1355 - 4 2026-07-08
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
UAL286 United Airlines 3 2026-04-24
UAL2821 - 3 2026-06-30
UAL2745 - 3 2026-07-13
UAL2652 - 3 2026-07-07
UAL2470 - 3 2026-06-21
UAL2350 - 3 2026-06-23
UAL2327 - 3 2026-07-11
UAL2281 United Airlines 3 2026-05-20
UAL2181 - 3 2026-06-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 UAL1236 DEN → PHX Jul 14, 05:50 UTCJul 14, 07:15 UTC1h 25m
2026-07-13 UAL2786 GEG → DEN Jul 13, 23:30 UTCJul 14, 01:20 UTC1h 50m
2026-07-13 UAL324 DEN → GEG Jul 13, 20:15 UTCJul 13, 22:05 UTC1h 50m
2026-07-13 UAL586 SJC → DEN Jul 13, 15:55 UTCJul 13, 18:05 UTC2h 10m
2026-07-13 UAL2745 DEN → SJC Jul 13, 02:05 UTCJul 13, 04:05 UTC2h 0m
2026-07-12 UAL2660 SAV → DEN Jul 12, 21:20 UTCJul 13, 00:25 UTC3h 5m
2026-07-12 UAL1049 DEN → SAV Jul 12, 16:30 UTCJul 12, 19:20 UTC2h 50m
2026-07-12 UAL2865 SBA → DEN Jul 12, 12:20 UTCJul 12, 14:20 UTC2h 0m
2026-07-12 UAL2479 DEN → SBA Jul 12, 01:50 UTCJul 12, 03:51 UTC2h 1m
2026-07-12 UAL2479 - Jul 12, 01:50 UTCJul 12, 03:50 UTC2h 0m
2026-07-11 UAL1943 - Jul 11, 22:45 UTCJul 11, 23:55 UTC1h 10m
2026-07-11 UAL2327 - Jul 11, 20:10 UTCJul 11, 21:10 UTC1h 0m
2026-07-11 UAL2327 DEN → OMA Jul 11, 20:09 UTCJul 11, 21:10 UTC1h 1m
2026-07-11 UAL640 YVR → DEN Jul 11, 15:55 UTCJul 11, 18:15 UTC2h 20m
2026-07-11 UAL1910 DEN → YVR Jul 11, 04:20 UTCJul 11, 06:50 UTC2h 30m
2026-07-11 UAL1910 DEN → YVR Jul 11, 04:21 UTCJul 11, 06:47 UTC2h 26m
2026-07-11 UAL2395 - Jul 11, 01:25 UTCJul 11, 02:50 UTC1h 25m
2026-07-10 UAL8123 - Jul 10, 21:25 UTCJul 10, 22:40 UTC1h 15m
2026-07-10 UAL2309 - Jul 10, 19:00 UTCJul 10, 20:10 UTC1h 10m
2026-07-10 UAL444 - Jul 10, 15:45 UTCJul 10, 17:00 UTC1h 15m
2026-07-10 UAL1896 PDX → SFO Jul 10, 12:30 UTCJul 10, 13:55 UTC1h 25m
2026-07-09 UAL2817 ORD → PDX Jul 9, 18:50 UTCJul 9, 22:40 UTC3h 50m
2026-07-09 UAL533 ORD → ORD Jul 9, 02:05 UTCJul 9, 16:55 UTC14h 50m
2026-07-08 UAL2401 ORD → ORD Jul 8, 16:00 UTCJul 8, 23:05 UTC7h 5m
2026-07-08 UAL1355 - Jul 8, 13:10 UTCJul 8, 14:15 UTC1h 5m
2026-07-07 UAL2652 ORD → CLE Jul 7, 23:50 UTCJul 8, 00:35 UTC45m
2026-07-07 UAL1325 DCA → ORD Jul 7, 20:15 UTCJul 7, 22:00 UTC1h 45m
2026-07-07 UAL2668 ORD → DCA Jul 7, 16:40 UTCJul 7, 18:05 UTC1h 25m
2026-07-07 UAL1355 - Jul 7, 13:10 UTCJul 7, 14:25 UTC1h 15m
2026-07-07 UAL8196 SFO → CLE Jul 7, 07:10 UTCJul 7, 11:25 UTC4h 15m
2026-07-07 UAL8196 SFO → CLE Jul 7, 06:55 UTCJul 7, 11:19 UTC4h 24m
2026-07-07 UAL2854 BUR → SFO Jul 7, 04:45 UTCJul 7, 05:45 UTC1h 0m
2026-07-07 UAL1321 SFO → BUR Jul 7, 01:20 UTCJul 7, 02:10 UTC50m
2026-07-07 UAL1321 SFO → BUR Jul 7, 01:20 UTCJul 7, 02:07 UTC47m
2026-07-06 UAL1931 - Jul 6, 21:40 UTCJul 6, 23:00 UTC1h 20m
2026-07-06 UAL1189 - Jul 6, 16:10 UTCJul 6, 16:30 UTC20m
2026-07-06 UAL1189 SFO → SJD Jul 6, 16:08 UTCJul 6, 18:45 UTC2h 37m
2026-07-06 UAL1388 BUR → SFO Jul 6, 05:50 UTCJul 6, 06:50 UTC1h 0m
2026-07-06 UAL1388 BUR → SFO Jul 6, 05:07 UTCJul 6, 06:42 UTC1h 35m
2026-07-06 UAL2411 DEN → BUR Jul 6, 01:30 UTCJul 6, 03:30 UTC2h 0m
2026-07-05 UAL1943 - Jul 5, 22:45 UTCJul 5, 23:55 UTC1h 10m
2026-07-05 UAL2327 - Jul 5, 20:05 UTCJul 5, 21:10 UTC1h 5m
2026-07-05 UAL640 YVR → DEN Jul 5, 15:55 UTCJul 5, 18:15 UTC2h 20m
2026-07-05 UAL1910 DEN → YVR Jul 5, 03:25 UTCJul 5, 06:00 UTC2h 35m
2026-07-04 UAL338 - Jul 4, 22:35 UTCJul 5, 00:35 UTC2h 0m
2026-07-04 UAL452 - Jul 4, 18:05 UTCJul 4, 19:05 UTC1h 0m
2026-07-04 UAL452 DEN → SJD Jul 4, 17:59 UTCJul 4, 20:30 UTC2h 31m
2026-07-04 UAL644 DFW → DEN Jul 4, 14:05 UTCJul 4, 16:05 UTC2h 0m
2026-07-04 UAL1565 DEN → DFW Jul 4, 01:30 UTCJul 4, 03:00 UTC1h 30m
2026-07-03 UAL294 DEN → DEN Jul 3, 16:05 UTCJul 3, 23:00 UTC6h 55m

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?
Yes. Mode-S A9D59A is currently airborne.
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, UAL2742, UAL2167.