Apparatus

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sensors Mode-S transponder

A9B4DE

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N72405 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A9B4DE
Octal
52332336
Decimal
11,121,886
Country
US
Tail
N72405
Type
B739
Broadcasting now · callsign UAL2406 · 450 ft
Flights observed
445
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 17:55 UTC

Current position

A9B4DE is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A9B4DE 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
UAL1361 - 15 2026-07-15
UAL2833 - 11 2026-07-15
UAL2406 United Airlines 11 2026-07-22
UAL2310 - 11 2026-07-22
UAL1420 United Airlines 11 2026-07-26
UAL740 United Airlines 10 2026-07-18
UAL2662 United Airlines 10 2026-07-25
UAL1563 United Airlines 10 2026-07-19
UAL496 United Airlines 9 2026-07-20
UAL2215 United Airlines 9 2026-07-21
UAL1949 United Airlines 9 2026-07-23
UAL1936 United Airlines 9 2026-07-19
UAL1927 - 9 2026-07-18
UAL1872 United Airlines 9 2026-07-25
UAL2124 - 8 2026-06-30
UAL1493 United Airlines 8 2026-07-26
UAL1345 - 8 2026-07-01
UAL378 United Airlines 7 2026-05-16
UAL315 United Airlines 7 2026-07-24
UAL1971 - 7 2026-07-10

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1493 IAH → DEN Jul 26, 16:05 UTCJul 26, 17:55 UTC1h 50m
2026-07-26 UAL1493 IAH → DEN Jul 26, 16:12 UTCJul 26, 17:54 UTC1h 42m
2026-07-26 UAL2245 SEA → ORD Jul 26, 12:40 UTCJul 26, 14:35 UTC1h 55m
2026-07-26 UAL780 IAD → LAS Jul 26, 07:15 UTCJul 26, 10:55 UTC3h 40m
2026-07-26 UAL1420 MCO → EWR Jul 26, 01:45 UTCJul 26, 05:30 UTC3h 45m
2026-07-26 UAL1420 MCO → EWR Jul 26, 01:44 UTCJul 26, 05:24 UTC3h 40m
2026-07-25 UAL1872 DEN → AUS Jul 25, 21:35 UTCJul 25, 23:25 UTC1h 50m
2026-07-25 UAL1872 DEN → AUS Jul 25, 21:34 UTCJul 25, 23:21 UTC1h 47m
2026-07-25 UAL2662 DEN → PDX Jul 25, 17:50 UTCJul 25, 19:45 UTC1h 55m
2026-07-24 UAL1444 SFO → IAH Jul 24, 21:15 UTCJul 24, 23:45 UTC2h 30m
2026-07-24 UAL315 FLL → IAD Jul 24, 17:25 UTCJul 24, 19:45 UTC2h 20m
2026-07-24 UAL2827 IAH → ORD Jul 24, 14:45 UTCJul 24, 15:30 UTC45m
2026-07-24 UAL2250 IAH → SAT Jul 24, 12:35 UTCJul 24, 13:10 UTC35m
2026-07-23 UAL1949 ORD → DCA Jul 23, 22:10 UTCJul 24, 01:40 UTC3h 30m
2026-07-23 UAL1949 ORD → DCA Jul 23, 21:56 UTCJul 24, 01:50 UTC3h 54m
2026-07-23 UAL2773 HNL → ORD Jul 23, 17:35 UTCJul 23, 21:00 UTC3h 25m
2026-07-23 UAL722 ORD → FLL Jul 23, 13:15 UTCJul 23, 15:35 UTC2h 20m
2026-07-23 UAL722 ORD → FLL Jul 23, 13:17 UTCJul 23, 15:31 UTC2h 14m
2026-07-22 UAL277 IAD → SFO Jul 22, 22:45 UTCJul 23, 01:15 UTC2h 30m
2026-07-22 UAL2406 LAX → SFO Jul 22, 18:15 UTCJul 22, 20:15 UTC2h 0m
2026-07-22 UAL2310 - Jul 22, 14:50 UTCJul 22, 16:50 UTC2h 0m
2026-07-22 UAL1127 ORD → SFO Jul 22, 12:25 UTCJul 22, 13:20 UTC55m
2026-07-22 UAL1127 ORD → SFO Jul 22, 12:28 UTCJul 22, 13:24 UTC56m
2026-07-22 UAL2304 - Jul 22, 01:50 UTCJul 22, 02:45 UTC55m
2026-07-21 UAL1444 SFO → IAH Jul 21, 21:40 UTCJul 22, 00:15 UTC2h 35m
2026-07-21 UAL315 FLL → IAD Jul 21, 17:20 UTCJul 21, 19:40 UTC2h 20m
2026-07-21 UAL2827 - Jul 21, 14:50 UTCJul 21, 15:40 UTC50m
2026-07-21 UAL2250 - Jul 21, 12:30 UTCJul 21, 13:05 UTC35m
2026-07-21 UAL2215 FLL → EWR Jul 21, 00:30 UTCJul 21, 02:20 UTC1h 50m
2026-07-20 UAL496 EWR → SFO Jul 20, 20:30 UTCJul 20, 22:30 UTC2h 0m
2026-07-20 UAL1493 IAH → DEN Jul 20, 16:15 UTCJul 20, 18:15 UTC2h 0m
2026-07-20 UAL2245 IAH → MCO Jul 20, 12:40 UTCJul 20, 14:40 UTC2h 0m
2026-07-20 UAL780 IAD → LAS Jul 20, 07:30 UTCJul 20, 11:15 UTC3h 45m
2026-07-20 UAL1420 MCO → EWR Jul 20, 01:55 UTCJul 20, 05:35 UTC3h 40m
2026-07-19 UAL1872 DEN → AUS Jul 19, 21:35 UTCJul 19, 23:30 UTC1h 55m
2026-07-19 UAL2662 - Jul 19, 17:45 UTCJul 19, 19:50 UTC2h 5m
2026-07-19 UAL1936 SAV → EWR Jul 19, 13:00 UTCJul 19, 15:55 UTC2h 55m
2026-07-19 UAL1563 LIH → SFO Jul 19, 01:50 UTCJul 19, 04:30 UTC2h 40m
2026-07-18 UAL1927 - Jul 18, 20:40 UTCJul 19, 00:20 UTC3h 40m
2026-07-18 UAL740 SEA → DEN Jul 18, 15:50 UTCJul 18, 19:30 UTC3h 40m
2026-07-18 UAL678 - Jul 18, 13:25 UTCJul 18, 14:10 UTC45m
2026-07-18 UAL1950 KOA → SFO Jul 18, 01:50 UTCJul 18, 02:35 UTC45m
2026-07-17 UAL2293 - Jul 17, 19:25 UTCJul 17, 23:14 UTC3h 50m
2026-07-17 UAL2654 BNA → SFO Jul 17, 13:20 UTCJul 17, 17:20 UTC4h 0m
2026-07-17 UAL2654 BNA → SFO Jul 17, 13:17 UTCJul 17, 17:26 UTC4h 9m
2026-07-17 UAL2215 - Jul 17, 00:25 UTCJul 17, 02:20 UTC1h 55m
2026-07-16 UAL496 - Jul 16, 21:25 UTCJul 16, 23:15 UTC1h 50m
2026-07-16 UAL2253 - Jul 16, 17:20 UTCJul 16, 18:15 UTC55m
2026-07-16 UAL575 - Jul 16, 15:14 UTCJul 16, 16:00 UTC45m
2026-07-16 UAL1859 - Jul 16, 10:25 UTCJul 16, 12:44 UTC2h 20m

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 N72405 page for operator, model, and routing details .

Mode-S A9B4DE frequently asked

What is Mode-S code A9B4DE?
A9B4DE is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N72405.
Where is Mode-S A9B4DE registered?
Mode-S code A9B4DE 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 A9B4DE broadcasting right now?
Yes. Mode-S A9B4DE is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A9B4DE, octal 52332336, decimal 11,121,886.
What flights does A9B4DE operate?
Mode-S A9B4DE has broadcast 20 distinct callsigns, including UAL1361, UAL2833, UAL2406, UAL2310, UAL1420.