Apparatus

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sensors Mode-S transponder

A43EA2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37273 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A43EA2
Octal
51037242
Decimal
10,763,938
Country
US
Tail
N37273
Type
B738
Broadcasting now · callsign UAL2275 · 36,000 ft
Flights observed
454
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:55 UTC

Current position

A43EA2 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A43EA2 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
UAL275 - 7 2026-06-18
UAL8188 United Airlines 5 2026-04-18
UAL2342 United Airlines 5 2026-06-03
UAL8100 United Airlines 4 2026-05-31
UAL763 United Airlines 4 2026-07-02
UAL302 United Airlines 4 2026-05-26
UAL2188 - 4 2026-06-16
UAL211 United Airlines 4 2026-05-05
UAL2011 - 4 2026-07-06
UAL1911 - 4 2026-06-19
UAL1883 United Airlines 4 2026-06-05
UAL1819 United Airlines 4 2026-04-14
UAL1588 United Airlines 4 2026-06-27
UAL786 United Airlines 3 2026-06-14
UAL719 United Airlines 3 2026-07-21
UAL703 United Airlines 3 2026-07-26
UAL643 - 3 2026-06-28
UAL618 - 3 2026-07-03
UAL602 - 3 2026-07-18
UAL533 - 3 2026-07-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL478 DEN → ORD Jul 26, 20:35 UTCJul 26, 21:55 UTC1h 20m
2026-07-26 UAL703 DEN → BIL Jul 26, 18:07 UTCJul 26, 19:00 UTC53m
2026-07-26 UAL703 DEN → BIL Jul 26, 17:55 UTCJul 26, 19:00 UTC1h 5m
2026-07-26 UAL1727 LAS → SFO Jul 26, 13:10 UTCJul 26, 16:10 UTC3h 0m
2026-07-25 UAL248 BOS → IAH Jul 25, 23:55 UTCJul 26, 02:35 UTC2h 40m
2026-07-25 UAL2155 MSP → EWR Jul 25, 21:50 UTCJul 25, 22:45 UTC55m
2026-07-25 UAL2383 PHL → DEN Jul 25, 19:10 UTCJul 25, 20:05 UTC55m
2026-07-25 UAL1537 RSW → EWR Jul 25, 14:10 UTCJul 25, 17:35 UTC3h 25m
2026-07-25 UAL8110 YYZ → ATL Jul 25, 00:40 UTCJul 25, 03:35 UTC2h 55m
2026-07-25 UAL8110 YYZ → ATL Jul 25, 00:39 UTCJul 25, 03:33 UTC2h 54m
2026-07-24 UAL1534 EWR → FLL Jul 24, 21:20 UTCJul 24, 23:00 UTC1h 40m
2026-07-24 UAL2167 ORD → CVG Jul 24, 17:35 UTCJul 24, 19:20 UTC1h 45m
2026-07-24 UAL671 DEN → BZN Jul 24, 12:20 UTCJul 24, 15:30 UTC3h 10m
2026-07-23 UAL1485 DEN → SFO Jul 23, 23:10 UTCJul 24, 02:00 UTC2h 50m
2026-07-22 UAL2644 AUS → IAH Jul 22, 20:45 UTCJul 23, 00:30 UTC3h 45m
2026-07-22 UAL2644 AUS → IAH Jul 22, 20:29 UTCJul 23, 00:59 UTC4h 30m
2026-07-22 UAL1575 MSP → EWR Jul 22, 15:56 UTCJul 22, 18:53 UTC2h 57m
2026-07-22 UAL1575 MSP → EWR Jul 22, 15:55 UTCJul 22, 19:00 UTC3h 5m
2026-07-22 UAL2185 MFR → DEN Jul 22, 12:16 UTCJul 22, 14:10 UTC1h 54m
2026-07-22 UAL2185 MFR → DEN Jul 22, 12:05 UTCJul 22, 14:15 UTC2h 10m
2026-07-22 UAL663 DEN → ABQ Jul 22, 01:55 UTCJul 22, 04:00 UTC2h 5m
2026-07-21 UAL1262 ORD → BOS Jul 21, 22:20 UTCJul 21, 23:30 UTC1h 10m
2026-07-21 UAL2750 PVR → SFO Jul 21, 19:35 UTCJul 21, 20:55 UTC1h 20m
2026-07-21 UAL347 PHL → DEN Jul 21, 16:30 UTCJul 21, 17:50 UTC1h 20m
2026-07-21 UAL347 PHL → DEN Jul 21, 16:10 UTCJul 21, 17:55 UTC1h 45m
2026-07-21 UAL719 MIA → EWR Jul 21, 01:50 UTCJul 21, 03:45 UTC1h 55m
2026-07-20 UAL475 EWR → MCO Jul 20, 21:45 UTCJul 20, 23:55 UTC2h 9m
2026-07-20 UAL1029 LAX → DEN Jul 20, 17:50 UTCJul 20, 20:10 UTC2h 20m
2026-07-20 UAL1029 LAX → DEN Jul 20, 17:50 UTCJul 20, 20:10 UTC2h 20m
2026-07-20 UAL2270 LAS → IAH Jul 20, 12:10 UTCJul 20, 15:35 UTC3h 25m
2026-07-20 UAL680 SAT → DEN Jul 20, 01:10 UTCJul 20, 04:10 UTC3h 0m
2026-07-19 UAL2239 DEN → SFO Jul 19, 19:55 UTCJul 19, 23:35 UTC3h 40m
2026-07-19 UAL2195 ORD → IAH Jul 19, 16:30 UTCJul 19, 18:10 UTC1h 40m
2026-07-19 UAL2486 SAN → ORD Jul 19, 01:55 UTCJul 19, 05:50 UTC3h 55m
2026-07-18 UAL2683 ORD → SAN Jul 18, 18:40 UTCJul 18, 22:05 UTC3h 25m
2026-07-18 UAL1693 - Jul 18, 14:30 UTCJul 18, 16:40 UTC2h 10m
2026-07-18 UAL533 - Jul 18, 05:20 UTCJul 18, 07:35 UTC2h 15m
2026-07-18 UAL602 - Jul 18, 04:00 UTCJul 18, 04:25 UTC25m
2026-07-18 UAL602 LGA → ORD Jul 18, 02:09 UTCJul 18, 04:25 UTC2h 16m
2026-07-18 UAL602 LGA → ORD Jul 18, 02:05 UTCJul 18, 03:44 UTC1h 39m
2026-07-17 UAL2189 - Jul 17, 22:35 UTCJul 18, 00:39 UTC2h 5m
2026-07-17 UAL511 DCA → ORD Jul 17, 17:35 UTCJul 17, 19:09 UTC1h 35m
2026-07-17 UAL511 IAH → SFO Jul 17, 17:24 UTCJul 17, 18:52 UTC1h 28m
2026-07-17 UAL2218 SJU → EWR Jul 17, 14:55 UTCJul 17, 16:19 UTC1h 25m
2026-07-17 UAL2218 SJU → EWR Jul 17, 14:37 UTCJul 17, 16:14 UTC1h 37m
2026-07-17 UAL1856 DEN → SFO Jul 17, 11:15 UTCJul 17, 12:10 UTC55m
2026-07-17 UAL1839 ORD → DSM Jul 17, 03:39 UTCJul 17, 04:25 UTC45m
2026-07-16 UAL2766 SMF → ORD Jul 16, 21:30 UTCJul 17, 01:35 UTC4h 5m
2026-07-16 UAL1415 DEN → SMF Jul 16, 17:49 UTCJul 16, 19:45 UTC1h 55m
2026-07-16 UAL2789 - Jul 16, 14:45 UTCJul 16, 15:49 UTC1h 5m

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 N37273 page for operator, model, and routing details .

Mode-S A43EA2 frequently asked

What is Mode-S code A43EA2?
A43EA2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37273.
Where is Mode-S A43EA2 registered?
Mode-S code A43EA2 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 A43EA2 broadcasting right now?
Yes. Mode-S A43EA2 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A43EA2, octal 51037242, decimal 10,763,938.
What flights does A43EA2 operate?
Mode-S A43EA2 has broadcast 20 distinct callsigns, including UAL275, UAL8188, UAL2342, UAL8100, UAL763.