Apparatus

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sensors Mode-S transponder

A43EC9

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37287 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A43EC9
Octal
51037311
Decimal
10,763,977
Country
US
Tail
N37287
Type
B738
No current signal · last broadcast Jul 26, 21:10 UTC
Flights observed
393
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:10 UTC

Last known position

Most recent position reported by Mode-S A43EC9.

Country allocation

The ICAO 24-bit address A43EC9 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
UAL2479 United Airlines 6 2026-05-21
UAL671 United Airlines 4 2026-07-22
UAL667 United Airlines 4 2026-07-24
UAL645 - 4 2026-07-11
UAL430 United Airlines 4 2026-07-24
UAL2865 United Airlines 4 2026-05-21
UAL2330 United Airlines 4 2026-05-11
UAL1375 United Airlines 4 2026-07-25
UAL1306 United Airlines 4 2026-04-18
UAL763 United Airlines 3 2026-05-25
UAL680 United Airlines 3 2026-05-07
UAL480 - 3 2026-07-16
UAL431 - 3 2026-07-19
UAL414 United Airlines 3 2026-05-08
UAL285 United Airlines 3 2026-04-28
UAL2750 United Airlines 3 2026-07-22
UAL2748 United Airlines 3 2026-04-15
UAL2745 - 3 2026-06-16
UAL2644 - 3 2026-07-18
UAL2383 - 3 2026-06-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1257 DEN → LGA Jul 26, 19:55 UTCJul 26, 21:10 UTC1h 15m
2026-07-25 UAL1931 SJD → SFO Jul 25, 21:35 UTCJul 25, 23:35 UTC2h 0m
2026-07-25 UAL1189 SFO → SJD Jul 25, 16:45 UTCJul 25, 18:45 UTC2h 0m
2026-07-25 UAL1189 SFO → SJD Jul 25, 16:46 UTCJul 25, 19:30 UTC2h 44m
2026-07-25 UAL1604 SFO → BNA Jul 25, 14:25 UTCJul 25, 15:20 UTC55m
2026-07-25 UAL589 DEN → RIC Jul 25, 02:45 UTCJul 25, 03:45 UTC1h 0m
2026-07-25 UAL1375 JAX → EWR Jul 25, 00:30 UTCJul 25, 01:35 UTC1h 5m
2026-07-25 UAL1375 JAX → EWR Jul 25, 00:12 UTCJul 25, 01:28 UTC1h 16m
2026-07-24 UAL430 BNA → EWR Jul 24, 17:30 UTCJul 24, 19:20 UTC1h 50m
2026-07-24 UAL1891 CLE → EWR Jul 24, 14:25 UTCJul 24, 16:05 UTC1h 40m
2026-07-24 UAL667 IAD → LAX Jul 24, 05:37 UTCJul 24, 06:57 UTC1h 20m
2026-07-24 UAL667 IAD → LAX Jul 24, 05:35 UTCJul 24, 07:00 UTC1h 25m
2026-07-24 UAL1787 SFO → DEN Jul 24, 02:00 UTCJul 24, 04:15 UTC2h 15m
2026-07-24 UAL1787 SFO → DEN Jul 24, 01:20 UTCJul 24, 04:19 UTC2h 59m
2026-07-23 UAL2455 EWR → ATL Jul 23, 21:55 UTCJul 24, 00:20 UTC2h 25m
2026-07-23 UAL347 PHL → DEN Jul 23, 16:20 UTCJul 23, 18:05 UTC1h 45m
2026-07-23 UAL719T DEN → RNO Jul 23, 05:35 UTCJul 23, 07:20 UTC1h 45m
2026-07-23 UAL719T DEN → RNO Jul 23, 05:33 UTCJul 23, 07:19 UTC1h 46m
2026-07-23 UAL1262 ORD → BOS Jul 23, 03:05 UTCJul 23, 04:15 UTC1h 10m
2026-07-22 UAL2750 PVR → SFO Jul 22, 19:45 UTCJul 22, 21:00 UTC1h 15m
2026-07-22 UAL671 DEN → BZN Jul 22, 15:35 UTCJul 22, 18:35 UTC3h 0m
2026-07-21 UAL1485 DEN → SFO Jul 21, 22:25 UTCJul 22, 01:15 UTC2h 50m
2026-07-21 UAL757 CLE → LAS Jul 21, 18:20 UTCJul 21, 20:35 UTC2h 15m
2026-07-21 UAL757 CLE → LAS Jul 21, 18:22 UTCJul 21, 20:30 UTC2h 8m
2026-07-21 UAL2271 LAX → SEA Jul 21, 14:35 UTCJul 21, 16:50 UTC2h 15m
2026-07-21 UAL362 HNL → EWR Jul 21, 10:40 UTCJul 21, 12:30 UTC1h 50m
2026-07-21 UAL1422 SFO → MFR Jul 21, 00:20 UTCJul 21, 01:50 UTC1h 30m
2026-07-20 UAL2446 - Jul 20, 12:05 UTCJul 20, 14:00 UTC1h 55m
2026-07-20 UAL2028 PHX → DEN Jul 20, 02:10 UTCJul 20, 03:55 UTC1h 45m
2026-07-19 UAL453 - Jul 19, 20:25 UTCJul 19, 23:45 UTC3h 20m
2026-07-19 UAL453 SYR → DEN Jul 19, 20:32 UTCJul 19, 23:40 UTC3h 8m
2026-07-19 UAL1909 - Jul 19, 16:00 UTCJul 19, 18:55 UTC2h 55m
2026-07-19 UAL1909 DEN → SYR Jul 19, 16:06 UTCJul 19, 19:00 UTC2h 54m
2026-07-19 UAL1877 IAH → EWR Jul 19, 13:20 UTCJul 19, 13:50 UTC30m
2026-07-19 UAL431 DEN → GJT Jul 19, 03:18 UTCJul 19, 03:52 UTC34m
2026-07-19 UAL431 - Jul 19, 03:15 UTCJul 19, 03:35 UTC20m
2026-07-18 UAL2644 PSQ → DEN Jul 18, 22:30 UTCJul 19, 01:55 UTC3h 25m
2026-07-18 UAL2644 PHL → DEN Jul 18, 21:02 UTCJul 19, 01:50 UTC4h 48m
2026-07-18 UAL2644 - Jul 18, 20:15 UTCJul 18, 21:45 UTC1h 30m
2026-07-18 UAL8154 YUL → EWR Jul 18, 16:45 UTCJul 18, 20:05 UTC3h 20m
2026-07-18 UAL596 LAS → DEN Jul 18, 13:00 UTCJul 18, 14:30 UTC1h 30m
2026-07-18 UAL2839 SFO → LAS Jul 18, 07:00 UTCJul 18, 08:00 UTC1h 0m
2026-07-18 UAL2837 - Jul 18, 04:10 UTCJul 18, 05:45 UTC1h 35m
2026-07-17 UAL574 - Jul 17, 23:50 UTCJul 18, 01:20 UTC1h 30m
2026-07-17 UAL1375 JAX → EWR Jul 17, 21:39 UTCJul 17, 22:35 UTC55m
2026-07-17 UAL430 DEN → ONT Jul 17, 17:47 UTCJul 17, 19:28 UTC1h 41m
2026-07-17 UAL430 DEN → ONT Jul 17, 17:40 UTCJul 17, 19:25 UTC1h 45m
2026-07-17 UAL2493 - Jul 17, 12:19 UTCJul 17, 15:29 UTC3h 10m
2026-07-17 UAL1534 - Jul 17, 00:30 UTCJul 17, 03:20 UTC2h 50m
2026-07-16 UAL1389 - Jul 16, 19:45 UTCJul 16, 22:15 UTC2h 30m

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 N37287 page for operator, model, and routing details .

Mode-S A43EC9 frequently asked

What is Mode-S code A43EC9?
A43EC9 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37287.
Where is Mode-S A43EC9 registered?
Mode-S code A43EC9 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 A43EC9 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:10 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A43EC9, octal 51037311, decimal 10,763,977.
What flights does A43EC9 operate?
Mode-S A43EC9 has broadcast 20 distinct callsigns, including UAL2479, UAL671, UAL667, UAL645, UAL430.