Apparatus

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sensors Mode-S transponder

A37FA1

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N32404 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A37FA1
Octal
50677641
Decimal
10,715,041
Country
US
Tail
N32404
Type
B739
No current signal · last broadcast 1h ago
Flights observed
405
Distinct callsigns
20
Country
US
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S A37FA1.

Country allocation

The ICAO 24-bit address A37FA1 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
UAL2310 - 15 2026-06-22
UAL1950 - 13 2026-07-09
UAL1563 - 13 2026-07-10
UAL678 - 10 2026-07-09
UAL2662 - 10 2026-07-10
UAL2170 - 10 2026-06-22
UAL1936 United Airlines 10 2026-07-10
UAL1872 - 10 2026-07-10
UAL496 - 9 2026-06-27
UAL2124 - 9 2026-07-12
UAL1361 - 9 2026-06-28
UAL1345 - 9 2026-07-08
UAL2406 - 8 2026-06-22
UAL2105 - 8 2026-06-23
UAL1752 - 8 2026-07-08
UAL2611 United Airlines 7 2026-06-28
UAL2456 United Airlines 7 2026-05-19
UAL1949 - 7 2026-07-11
UAL491 - 6 2026-06-23
UAL2399 United Airlines 6 2026-04-30

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 UAL315 - Jul 14, 18:30 UTCJul 14, 20:15 UTC1h 45m
2026-07-14 UAL2827 - Jul 14, 16:40 UTCJul 14, 17:20 UTC40m
2026-07-14 UAL2250 - Jul 14, 13:05 UTCJul 14, 13:55 UTC50m
2026-07-14 UAL8130 - Jul 14, 00:25 UTCJul 14, 03:15 UTC2h 50m
2026-07-13 UAL2748 - Jul 13, 20:15 UTCJul 13, 23:15 UTC3h 0m
2026-07-13 UAL1478 - Jul 13, 14:10 UTCJul 13, 18:30 UTC4h 20m
2026-07-13 UAL1478 YEG → IAH Jul 13, 14:25 UTCJul 13, 18:26 UTC4h 1m
2026-07-12 UAL241 - Jul 12, 22:15 UTCJul 13, 02:01 UTC3h 45m
2026-07-12 UAL539 - Jul 12, 17:35 UTCJul 12, 18:15 UTC40m
2026-07-12 UAL2074 - Jul 12, 15:20 UTCJul 12, 16:01 UTC40m
2026-07-12 UAL2074 IAH → DFW Jul 12, 15:05 UTCJul 12, 16:01 UTC56m
2026-07-12 UAL2124 - Jul 12, 12:10 UTCJul 12, 13:01 UTC50m
2026-07-12 UAL1696 - Jul 12, 02:01 UTCJul 12, 02:45 UTC45m
2026-07-11 UAL1949 - Jul 11, 20:30 UTCJul 12, 00:01 UTC3h 30m
2026-07-11 UAL2773 - Jul 11, 15:50 UTCJul 11, 19:05 UTC3h 15m
2026-07-11 UAL396 - Jul 11, 11:45 UTCJul 11, 13:20 UTC1h 35m
2026-07-11 UAL1326 - Jul 11, 01:45 UTCJul 11, 03:15 UTC1h 30m
2026-07-10 UAL1872 - Jul 10, 21:40 UTCJul 10, 23:40 UTC2h 0m
2026-07-10 UAL2662 - Jul 10, 17:45 UTCJul 10, 19:40 UTC1h 55m
2026-07-10 UAL1936 SAV → EWR Jul 10, 12:50 UTCJul 10, 15:40 UTC2h 50m
2026-07-10 UAL1563 - Jul 10, 01:50 UTCJul 10, 04:30 UTC2h 40m
2026-07-10 UAL1563 IAH → ONT Jul 10, 01:51 UTCJul 10, 04:27 UTC2h 36m
2026-07-09 UAL1927 - Jul 9, 20:15 UTCJul 10, 00:00 UTC3h 45m
2026-07-09 UAL740 - Jul 9, 14:45 UTCJul 9, 18:35 UTC3h 50m
2026-07-09 UAL678 - Jul 9, 12:10 UTCJul 9, 13:05 UTC55m
2026-07-09 UAL1950 - Jul 9, 01:50 UTCJul 9, 02:35 UTC45m
2026-07-08 UAL1752 - Jul 8, 21:20 UTCJul 8, 23:20 UTC2h 0m
2026-07-08 UAL1345 - Jul 8, 17:40 UTCJul 8, 19:55 UTC2h 15m
2026-07-08 UAL2314 - Jul 8, 11:15 UTCJul 8, 13:25 UTC2h 10m
2026-07-07 UAL1706 - Jul 7, 17:45 UTCJul 7, 19:50 UTC2h 5m
2026-07-07 UAL2449 - Jul 7, 00:00 UTCJul 7, 02:35 UTC2h 35m
2026-07-07 UAL2449 LAS → IAH Jul 7, 00:04 UTCJul 7, 02:31 UTC2h 27m
2026-07-06 UAL1971 - Jul 6, 19:30 UTCJul 6, 22:15 UTC2h 45m
2026-07-06 UAL1971 IAH → LAS Jul 6, 19:40 UTCJul 6, 22:15 UTC2h 35m
2026-07-06 UAL2812 - Jul 6, 15:50 UTCJul 6, 18:00 UTC2h 10m
2026-07-06 UAL2078 BOS → ORD Jul 6, 01:15 UTCJul 6, 03:20 UTC2h 5m
2026-07-05 UAL2293 - Jul 5, 19:20 UTCJul 5, 23:10 UTC3h 50m
2026-07-05 UAL2654 - Jul 5, 13:20 UTCJul 5, 17:40 UTC4h 20m
2026-07-05 UAL566 - Jul 5, 02:45 UTCJul 5, 04:50 UTC2h 5m
2026-07-04 UAL447 - Jul 4, 14:45 UTCJul 4, 17:10 UTC2h 25m
2026-07-04 UAL447 IAH → PBI Jul 4, 14:56 UTCJul 4, 16:55 UTC1h 59m
2026-07-04 UAL678 - Jul 4, 12:15 UTCJul 4, 13:05 UTC50m
2026-07-04 UAL1950 - Jul 4, 01:50 UTCJul 4, 02:35 UTC45m
2026-07-03 UAL1927 - Jul 3, 20:20 UTCJul 4, 00:00 UTC3h 40m
2026-07-03 UAL740 - Jul 3, 14:50 UTCJul 3, 18:40 UTC3h 50m
2026-07-03 UAL1898 - Jul 3, 10:20 UTCJul 3, 12:55 UTC2h 35m
2026-07-03 UAL1898 BWI → IAH Jul 3, 10:12 UTCJul 3, 12:54 UTC2h 42m
2026-07-03 UAL1795 - Jul 3, 00:15 UTCJul 3, 02:55 UTC2h 40m
2026-07-02 UAL2237 - Jul 2, 19:55 UTCJul 2, 22:30 UTC2h 35m
2026-07-02 UAL2491 SFO → DEN Jul 2, 15:30 UTCJul 2, 18:20 UTC2h 50m

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 N32404 page for operator, model, and routing details .

Mode-S A37FA1 frequently asked

What is Mode-S code A37FA1?
A37FA1 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N32404.
Where is Mode-S A37FA1 registered?
Mode-S code A37FA1 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 A37FA1 broadcasting right now?
No active broadcast right now. Last signal was 1h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A37FA1, octal 50677641, decimal 10,715,041.
What flights does A37FA1 operate?
Mode-S A37FA1 has broadcast 20 distinct callsigns, including UAL2310, UAL1950, UAL1563, UAL678, UAL2662.