Apparatus

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sensors Mode-S transponder

A537B2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N435WN · BOEING 737-700 · operated by SOUTHWEST AIRLINES CO

Hex
A537B2
Octal
51233662
Decimal
10,827,698
Country
US
Tail
N435WN
Type
B737
Broadcasting now · callsign SWA4098 · 37,000 ft
Flights observed
753
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Current position

A537B2 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A537B2 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
SWA66 - 7 2026-07-11
SWA1219 Southwest Airlines 7 2026-04-25
SWA4523 - 5 2026-07-15
SWA416 Southwest Airlines 5 2026-04-18
SWA1839 Southwest Airlines 5 2026-07-25
SWA1655 Southwest Airlines 5 2026-04-24
SWA8 Southwest Airlines 4 2026-04-16
SWA686 Southwest Airlines 4 2026-06-06
SWA599 - 4 2026-07-22
SWA400 - 4 2026-06-24
SWA389 Southwest Airlines 4 2026-05-30
SWA2693 - 4 2026-06-20
SWA264 - 4 2026-07-09
SWA2117 Southwest Airlines 4 2026-05-22
SWA2051 - 4 2026-06-19
SWA2012 Southwest Airlines 4 2026-07-24
SWA1771 - 4 2026-07-06
SWA1577 - 4 2026-07-14
SWA1409 Southwest Airlines 4 2026-05-31
SWA138 Southwest Airlines 4 2026-07-25

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SWA1955 MDW → STL Jul 26, 20:40 UTCJul 26, 21:45 UTC1h 5m
2026-07-26 SWA2978 MCO → MSY Jul 26, 17:50 UTCJul 26, 18:50 UTC1h 0m
2026-07-26 SWA2978 MCO → MSY Jul 26, 17:45 UTCJul 26, 19:06 UTC1h 21m
2026-07-26 SWA1204 OAK → LAX Jul 26, 14:55 UTCJul 26, 16:00 UTC1h 5m
2026-07-26 SWA547 MDW → BDL Jul 26, 13:15 UTCJul 26, 14:00 UTC45m
2026-07-26 SWA2772 LAS → OMA Jul 26, 00:41 UTCJul 26, 05:17 UTC4h 36m
2026-07-26 SWA2772 LAS → OMA Jul 26, 00:45 UTCJul 26, 05:20 UTC4h 35m
2026-07-25 SWA910 PHX → SAN Jul 25, 20:15 UTCJul 25, 22:30 UTC2h 15m
2026-07-25 SWA1839 MDW → CLT Jul 25, 15:05 UTCJul 25, 18:10 UTC3h 5m
2026-07-25 SWA1839 MDW → CLT Jul 25, 13:20 UTCJul 25, 14:05 UTC45m
2026-07-25 SWA373 SNA → SJC Jul 25, 06:30 UTCJul 25, 07:20 UTC50m
2026-07-25 SWA138 OAK → LAS Jul 25, 04:30 UTCJul 25, 05:40 UTC1h 10m
2026-07-25 SWA138 OAK → LAS Jul 25, 04:27 UTCJul 25, 05:34 UTC1h 8m
2026-07-25 SWA138 OAK → LAS Jul 25, 02:35 UTCJul 25, 03:30 UTC55m
2026-07-24 SWA138 OAK → LAS Jul 24, 22:00 UTCJul 25, 00:00 UTC2h 0m
2026-07-24 SWA1493 OAK → LAX Jul 24, 19:50 UTCJul 24, 20:50 UTC1h 0m
2026-07-24 SWA4805 MCO → BDL Jul 24, 17:20 UTCJul 24, 18:45 UTC1h 25m
2026-07-24 SWA4805 MCO → BDL Jul 24, 17:17 UTCJul 24, 18:41 UTC1h 24m
2026-07-24 SWA146 - Jul 24, 15:05 UTCJul 24, 16:20 UTC1h 15m
2026-07-24 SWA146 ABQ → PHX Jul 24, 12:50 UTCJul 24, 13:45 UTC55m
2026-07-24 SWA2177 SAN → OAK Jul 24, 05:00 UTCJul 24, 06:10 UTC1h 10m
2026-07-24 SWA2177 SAN → OAK Jul 24, 04:59 UTCJul 24, 06:05 UTC1h 6m
2026-07-24 SWA2177 SAN → OAK Jul 24, 03:20 UTCJul 24, 04:20 UTC1h 0m
2026-07-24 SWA2012 PDX → OAK Jul 24, 01:15 UTCJul 24, 02:05 UTC50m
2026-07-23 SWA2012 PDX → OAK Jul 23, 22:00 UTCJul 23, 23:50 UTC1h 50m
2026-07-23 SWA2012 PDX → OAK Jul 23, 20:10 UTCJul 23, 21:10 UTC1h 0m
2026-07-23 SWA2824 - Jul 23, 17:50 UTCJul 23, 19:00 UTC1h 10m
2026-07-23 SWA2824 MEM → HOU Jul 23, 17:44 UTCJul 23, 18:56 UTC1h 12m
2026-07-23 SWA2824 - Jul 23, 15:40 UTCJul 23, 16:40 UTC1h 0m
2026-07-23 SWA4316 BWI → SAN Jul 23, 13:30 UTCJul 23, 14:35 UTC1h 5m
2026-07-23 SWA2845 RDU → BWI Jul 23, 02:05 UTCJul 23, 03:05 UTC1h 0m
2026-07-22 SWA4073 PHX → DAL Jul 22, 23:40 UTCJul 23, 00:50 UTC1h 10m
2026-07-22 SWA3451 DCA → MDW Jul 22, 20:50 UTCJul 22, 22:40 UTC1h 50m
2026-07-22 SWA599 - Jul 22, 18:45 UTCJul 22, 19:25 UTC40m
2026-07-22 SWA599 NAS → MCO Jul 22, 18:26 UTCJul 22, 19:21 UTC55m
2026-07-22 SWA600 - Jul 22, 16:15 UTCJul 22, 16:50 UTC35m
2026-07-22 SWA3888 IAH → DEN Jul 22, 12:10 UTCJul 22, 14:20 UTC2h 10m
2026-07-22 SWA3888 IAH → DEN Jul 22, 12:08 UTCJul 22, 14:15 UTC2h 7m
2026-07-22 SWA1764 OMA → MDW Jul 22, 04:40 UTCJul 22, 05:25 UTC45m
2026-07-22 SWA1764 OMA → MDW Jul 22, 04:38 UTCJul 22, 05:50 UTC1h 12m
2026-07-22 SWA4151 MCO → BWI Jul 22, 01:25 UTCJul 22, 03:25 UTC2h 0m
2026-07-21 SWA3701 CMH → MDW Jul 21, 23:20 UTCJul 22, 00:25 UTC1h 5m
2026-07-21 SWA3701 CMH → MDW Jul 21, 23:25 UTCJul 22, 00:25 UTC1h 0m
2026-07-21 SWA1181 BNA → MDW Jul 21, 20:15 UTCJul 21, 21:10 UTC55m
2026-07-21 SWA1181 BNA → MDW Jul 21, 20:13 UTCJul 21, 21:09 UTC56m
2026-07-21 SWA1181 BNA → MDW Jul 21, 18:30 UTCJul 21, 19:25 UTC55m
2026-07-21 SWA839 LAX → OAK Jul 21, 04:40 UTCJul 21, 05:55 UTC1h 15m
2026-07-21 SWA4174 SAN → OAK Jul 21, 02:05 UTCJul 21, 04:00 UTC1h 55m
2026-07-20 SWA1645 - Jul 20, 22:30 UTCJul 21, 01:00 UTC2h 30m
2026-07-20 SWA3319 SLC → DEN Jul 20, 19:35 UTCJul 20, 21:20 UTC1h 45m

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 N435WN page for operator, model, and routing details .

Mode-S A537B2 frequently asked

What is Mode-S code A537B2?
A537B2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N435WN.
Where is Mode-S A537B2 registered?
Mode-S code A537B2 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 A537B2 broadcasting right now?
Yes. Mode-S A537B2 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A537B2, octal 51233662, decimal 10,827,698.
What flights does A537B2 operate?
Mode-S A537B2 has broadcast 20 distinct callsigns, including SWA66, SWA1219, SWA4523, SWA416, SWA1839.