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
No current signal · last broadcast 8h ago
Flights observed
661
Distinct callsigns
20
Country
US
Last broadcast
8h ago

Last known position

Most recent position reported by Mode-S A537B2.

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
SWA1655 Southwest Airlines 5 2026-04-24
SWA8 Southwest Airlines 4 2026-04-16
SWA686 Southwest Airlines 4 2026-06-06
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
SWA1771 - 4 2026-07-06
SWA1577 - 4 2026-07-14
SWA1409 Southwest Airlines 4 2026-05-31
SWA1268 Southwest Airlines 4 2026-06-05
SWA1095 Southwest Airlines 4 2026-06-01
SWA1089 Southwest Airlines 4 2026-05-26
SWA859 - 3 2026-06-25

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-15 SWA4865 - Jul 15, 03:30 UTCJul 15, 04:20 UTC50m
2026-07-15 SWA4523 - Jul 15, 01:45 UTCJul 15, 02:35 UTC50m
2026-07-15 SWA4523 PHX → LGB Jul 15, 00:05 UTCJul 15, 01:00 UTC55m
2026-07-14 SWA3064 BUR → PHX Jul 14, 22:00 UTCJul 14, 23:00 UTC59m
2026-07-14 SWA3064 BUR → PHX Jul 14, 21:56 UTCJul 14, 22:59 UTC1h 3m
2026-07-14 SWA1577 - Jul 14, 20:20 UTCJul 14, 21:10 UTC50m
2026-07-14 SWA1577 DEN → OAK Jul 14, 17:25 UTCJul 14, 19:20 UTC1h 55m
2026-07-14 SWA1577 - Jul 14, 14:45 UTCJul 14, 16:05 UTC1h 20m
2026-07-14 SWA1577 - Jul 14, 11:20 UTCJul 14, 13:20 UTC2h 0m
2026-07-14 SWA4990 ATL → DCA Jul 14, 04:55 UTCJul 14, 06:15 UTC1h 20m
2026-07-14 SWA9015 MCO → ATL Jul 14, 03:00 UTCJul 14, 04:05 UTC1h 5m
2026-07-13 SWA2034 - Jul 13, 22:30 UTCJul 14, 00:35 UTC2h 5m
2026-07-13 SWA2034 - Jul 13, 19:30 UTCJul 13, 20:30 UTC1h 0m
2026-07-13 SWA2034 - Jul 13, 13:50 UTCJul 13, 17:40 UTC3h 50m
2026-07-13 SWA4052 - Jul 13, 06:15 UTCJul 13, 07:10 UTC55m
2026-07-13 SWA4052 PHX → SAN Jul 13, 06:12 UTCJul 13, 07:01 UTC49m
2026-07-13 SWA3070 - Jul 13, 02:25 UTCJul 13, 04:10 UTC1h 45m
2026-07-13 SWA1592 LAS → OAK Jul 13, 00:15 UTCJul 13, 01:15 UTC1h 0m
2026-07-12 SWA240 - Jul 12, 20:05 UTCJul 12, 22:55 UTC2h 50m
2026-07-12 SWA240 ATL → STL Jul 12, 17:55 UTCJul 12, 19:05 UTC1h 10m
2026-07-12 SWA3285 LAS → LBB Jul 12, 15:25 UTCJul 12, 16:35 UTC1h 10m
2026-07-12 SWA3139 - Jul 12, 13:30 UTCJul 12, 14:25 UTC55m
2026-07-12 SWA2845 - Jul 12, 01:50 UTCJul 12, 02:45 UTC55m
2026-07-12 SWA2845 MDW → OMA Jul 12, 01:46 UTCJul 12, 02:48 UTC1h 2m
2026-07-11 SWA66 - Jul 11, 23:25 UTCJul 12, 00:10 UTC45m
2026-07-11 SWA66 - Jul 11, 21:00 UTCJul 11, 22:35 UTC1h 35m
2026-07-11 SWA66 - Jul 11, 18:25 UTCJul 11, 20:00 UTC1h 35m
2026-07-11 SWA875 - Jul 11, 15:20 UTCJul 11, 17:25 UTC2h 5m
2026-07-11 SWA875 PHX → DAL Jul 11, 15:20 UTCJul 11, 17:18 UTC1h 58m
2026-07-11 SWA2680 MCO → PHX Jul 11, 10:15 UTCJul 11, 14:00 UTC3h 45m
2026-07-10 SWA158 - Jul 10, 23:35 UTCJul 11, 02:10 UTC2h 35m
2026-07-10 SWA3129 - Jul 10, 20:20 UTCJul 10, 22:35 UTC2h 15m
2026-07-10 SWA3329 - Jul 10, 18:20 UTCJul 10, 19:20 UTC1h 0m
2026-07-10 SWA3329 - Jul 10, 16:10 UTCJul 10, 17:20 UTC1h 10m
2026-07-10 SWA2669 - Jul 10, 14:05 UTCJul 10, 15:15 UTC1h 10m
2026-07-10 SWA4107 - Jul 10, 04:35 UTCJul 10, 05:25 UTC50m
2026-07-10 SWA820 - Jul 10, 02:15 UTCJul 10, 03:20 UTC1h 5m
2026-07-10 SWA820 BUR → PHX Jul 10, 02:13 UTCJul 10, 03:18 UTC1h 5m
2026-07-09 SWA2411 AUS → BUR Jul 9, 22:15 UTCJul 10, 00:55 UTC2h 40m
2026-07-09 SWA2411 - Jul 9, 20:30 UTCJul 9, 21:05 UTC35m
2026-07-09 SWA264 LGB → DAL Jul 9, 16:30 UTCJul 9, 19:10 UTC2h 40m
2026-07-09 SWA264 LGB → DAL Jul 9, 16:29 UTCJul 9, 19:04 UTC2h 35m
2026-07-09 SWA264 OAK → LGB Jul 9, 14:35 UTCJul 9, 15:35 UTC1h 0m
2026-07-09 SWA264 PDX → OAK Jul 9, 12:15 UTCJul 9, 13:35 UTC1h 20m
2026-07-09 SWA384 - Jul 9, 05:10 UTCJul 9, 06:35 UTC1h 25m
2026-07-09 SWA384 SJC → PDX Jul 9, 05:09 UTCJul 9, 06:36 UTC1h 27m
2026-07-09 SWA384 BUR → SJC Jul 9, 03:40 UTCJul 9, 04:25 UTC45m
2026-07-09 SWA9004 LAS → BUR Jul 9, 02:15 UTCJul 9, 03:00 UTC45m
2026-07-09 SWA791 BUR → LAS Jul 9, 00:05 UTCJul 9, 00:50 UTC45m
2026-07-09 SWA791 BUR → LAS Jul 9, 00:04 UTCJul 9, 00:45 UTC41m

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?
No active broadcast right now. Last signal was 8h ago.
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, SWA1655.