Apparatus

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sensors Mode-S transponder

A43EC3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37281 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A43EC3
Octal
51037303
Decimal
10,763,971
Country
US
Tail
N37281
Type
B738
Broadcasting now · callsign UAL478 · 8,825 ft
Flights observed
451
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:50 UTC

Current position

A43EC3 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A43EC3 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
UAL2724 United Airlines 6 2026-07-26
UAL2725 United Airlines 5 2026-05-25
UAL1973 - 5 2026-06-29
UAL2457 United Airlines 4 2026-04-29
UAL2442 United Airlines 4 2026-07-17
UAL2267 United Airlines 4 2026-07-20
UAL2144 United Airlines 4 2026-05-19
UAL1286 - 4 2026-07-04
UAL840 United Airlines 3 2026-05-04
UAL497 United Airlines 3 2026-04-28
UAL480 - 3 2026-06-18
UAL329 United Airlines 3 2026-06-12
UAL275 - 3 2026-07-02
UAL2693 United Airlines 3 2026-04-15
UAL2449 - 3 2026-07-13
UAL2427 United Airlines 3 2026-05-19
UAL2337 United Airlines 3 2026-07-24
UAL2205 - 3 2026-07-17
UAL2203 United Airlines 3 2026-04-14
UAL2069 United Airlines 3 2026-07-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2724 LAS → SFO Jul 26, 19:40 UTCJul 26, 21:50 UTC2h 10m
2026-07-26 UAL2724 LAS → SFO Jul 26, 15:20 UTCJul 26, 17:25 UTC2h 5m
2026-07-26 UAL8207 EWR → YUL Jul 26, 00:35 UTCJul 26, 04:40 UTC4h 5m
2026-07-25 UAL2409 PHL → ORD Jul 25, 20:35 UTCJul 25, 23:10 UTC2h 35m
2026-07-25 UAL2409 PHL → ORD Jul 25, 20:34 UTCJul 25, 23:03 UTC2h 29m
2026-07-25 UAL2647 DCA → IAH Jul 25, 17:20 UTCJul 25, 19:15 UTC1h 55m
2026-07-25 UAL694 SFO → KOA Jul 25, 12:10 UTCJul 25, 15:15 UTC3h 5m
2026-07-24 UAL2337 SFO → BOS Jul 24, 22:35 UTCJul 25, 01:20 UTC2h 45m
2026-07-24 UAL1140 LAX → IAD Jul 24, 16:15 UTCJul 24, 20:20 UTC4h 5m
2026-07-24 UAL582 SFO → LAS Jul 24, 13:15 UTCJul 24, 14:20 UTC1h 5m
2026-07-24 UAL2056 LAS → SFO Jul 24, 05:30 UTCJul 24, 06:25 UTC55m
2026-07-24 UAL1427 MID → IAH Jul 24, 02:30 UTCJul 24, 03:25 UTC55m
2026-07-24 UAL2019 OGG → SFO Jul 24, 00:15 UTCJul 24, 01:05 UTC50m
2026-07-23 UAL547 IAH → SFO Jul 23, 20:25 UTCJul 23, 21:35 UTC1h 10m
2026-07-23 UAL1185 LAX → SJD Jul 23, 16:15 UTCJul 23, 16:50 UTC35m
2026-07-23 UAL1185 LAX → SJD Jul 23, 16:13 UTCJul 23, 18:17 UTC2h 4m
2026-07-23 UAL2179 LGA → ORD Jul 23, 06:40 UTCJul 23, 07:35 UTC55m
2026-07-23 UAL1195 DTW → ORD Jul 23, 04:15 UTCJul 23, 05:10 UTC55m
2026-07-23 UAL741 LAS → EWR Jul 23, 00:05 UTCJul 23, 02:00 UTC1h 55m
2026-07-23 UAL741 LAS → EWR Jul 23, 00:00 UTCJul 23, 01:51 UTC1h 51m
2026-07-22 UAL2212 PHL → IAH Jul 22, 20:10 UTCJul 22, 21:45 UTC1h 35m
2026-07-22 UAL2212 PHL → IAH Jul 22, 20:08 UTCJul 22, 22:06 UTC1h 58m
2026-07-22 UAL2487 RSW → EWR Jul 22, 17:15 UTCJul 22, 18:10 UTC55m
2026-07-22 UAL1481 EWR → CLT Jul 22, 14:18 UTCJul 22, 15:40 UTC1h 22m
2026-07-22 UAL1481 EWR → CLT Jul 22, 14:15 UTCJul 22, 15:40 UTC1h 25m
2026-07-22 UAL1464 EWR → FLL Jul 22, 11:10 UTCJul 22, 12:35 UTC1h 25m
2026-07-22 UAL1542 SFO → YVR Jul 22, 01:30 UTCJul 22, 02:00 UTC30m
2026-07-22 UAL1542 SFO → YVR Jul 22, 01:25 UTCJul 22, 02:03 UTC38m
2026-07-21 UAL1601 EWR → BOS Jul 21, 20:45 UTCJul 21, 22:35 UTC1h 50m
2026-07-21 UAL1600 - Jul 21, 17:15 UTCJul 21, 19:05 UTC1h 50m
2026-07-21 UAL1957 PHL → IAH Jul 21, 12:05 UTCJul 21, 15:10 UTC3h 5m
2026-07-21 UAL1957 PHL → IAH Jul 21, 11:45 UTCJul 21, 15:06 UTC3h 21m
2026-07-21 UAL2605 - Jul 21, 00:55 UTCJul 21, 02:30 UTC1h 35m
2026-07-20 UAL1156 IAD → EWR Jul 20, 20:55 UTCJul 20, 23:00 UTC2h 5m
2026-07-20 UAL2267 EWR → RDU Jul 20, 17:25 UTCJul 20, 19:10 UTC1h 45m
2026-07-20 UAL2267 EWR → RDU Jul 20, 17:29 UTCJul 20, 19:02 UTC1h 33m
2026-07-20 UAL1057 DEN → SFO Jul 20, 13:35 UTCJul 20, 15:25 UTC1h 50m
2026-07-20 UAL1057 DEN → SFO Jul 20, 13:55 UTCJul 20, 15:50 UTC1h 55m
2026-07-19 UAL2306 ORD → BOS Jul 19, 23:18 UTCJul 20, 01:10 UTC1h 52m
2026-07-19 UAL2306 ORD → BOS Jul 19, 23:10 UTCJul 20, 00:45 UTC1h 35m
2026-07-19 UAL2005 DFW → SFO Jul 19, 19:20 UTCJul 19, 21:35 UTC2h 15m
2026-07-19 UAL2672 ORD → PNS Jul 19, 15:55 UTCJul 19, 17:45 UTC1h 50m
2026-07-19 UAL2151 PDX → DEN Jul 19, 13:20 UTCJul 19, 13:55 UTC35m
2026-07-19 UAL630T ORD → MSN Jul 19, 06:00 UTCJul 19, 06:35 UTC35m
2026-07-19 UAL704 IAH → EWR Jul 19, 00:25 UTCJul 19, 04:00 UTC3h 35m
2026-07-19 UAL704 IAH → EWR Jul 19, 00:27 UTCJul 19, 03:44 UTC3h 17m
2026-07-18 UAL785 - Jul 18, 15:45 UTCJul 18, 19:20 UTC3h 35m
2026-07-18 UAL2151 PDX → DEN Jul 18, 13:47 UTCJul 18, 13:49 UTC2m
2026-07-18 UAL630 - Jul 18, 04:30 UTCJul 18, 05:05 UTC35m
2026-07-18 UAL630 ORD → MSN Jul 18, 04:34 UTCJul 18, 05:00 UTC26m

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 N37281 page for operator, model, and routing details .

Mode-S A43EC3 frequently asked

What is Mode-S code A43EC3?
A43EC3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37281.
Where is Mode-S A43EC3 registered?
Mode-S code A43EC3 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 A43EC3 broadcasting right now?
Yes. Mode-S A43EC3 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A43EC3, octal 51037303, decimal 10,763,971.
What flights does A43EC3 operate?
Mode-S A43EC3 has broadcast 20 distinct callsigns, including UAL2724, UAL2725, UAL1973, UAL2457, UAL2442.