Apparatus

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sensors Mode-S transponder

A53F20

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N437WN · BOEING 737-700 · operated by SOUTHWEST AIRLINES CO

Hex
A53F20
Octal
51237440
Decimal
10,829,600
Country
US
Tail
N437WN
Type
B737
No current signal · last broadcast 21m ago
Flights observed
612
Distinct callsigns
20
Country
US
Last broadcast
21m ago

Last known position

Most recent position reported by Mode-S A53F20.

Country allocation

The ICAO 24-bit address A53F20 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
SWA1396 Southwest Airlines 7 2026-06-11
SWA380 - 6 2026-07-09
SWA2310 - 5 2026-07-10
SWA1840 Southwest Airlines 5 2026-06-12
SWA881 Southwest Airlines 4 2026-06-10
SWA4389 - 4 2026-06-23
SWA3828 - 4 2026-06-26
SWA3151 - 4 2026-06-19
SWA311 Southwest Airlines 4 2026-06-04
SWA2997 Southwest Airlines 4 2026-06-07
SWA2820 - 4 2026-07-11
SWA2624 Southwest Airlines 4 2026-05-17
SWA1642 - 4 2026-06-26
SWA1530 - 4 2026-07-06
SWA971 Southwest Airlines 3 2026-05-18
SWA9002 Southwest Airlines 3 2026-06-20
SWA8513 - 3 2026-07-04
SWA839 Southwest Airlines 3 2026-05-12
SWA800 Southwest Airlines 3 2026-06-13
SWA727 Southwest Airlines 3 2026-04-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 SWA1400 - Jul 14, 17:05 UTCJul 14, 18:00 UTC55m
2026-07-14 SWA1400 - Jul 14, 15:20 UTCJul 14, 16:00 UTC40m
2026-07-14 SWA1400 - Jul 14, 13:20 UTCJul 14, 14:00 UTC40m
2026-07-14 SWA4705 - Jul 14, 11:15 UTCJul 14, 12:00 UTC45m
2026-07-14 SWA4437 - Jul 14, 00:30 UTCJul 14, 01:35 UTC1h 5m
2026-07-13 SWA3414 - Jul 13, 21:50 UTCJul 13, 23:10 UTC1h 20m
2026-07-13 SWA3414 PWM → BWI Jul 13, 21:44 UTCJul 13, 23:02 UTC1h 18m
2026-07-13 SWA297 - Jul 13, 19:45 UTCJul 13, 20:45 UTC1h 0m
2026-07-13 SWA297 - Jul 13, 17:35 UTCJul 13, 18:15 UTC40m
2026-07-13 SWA297 - Jul 13, 15:00 UTCJul 13, 16:35 UTC1h 35m
2026-07-13 SWA4853 DCA → STL Jul 13, 12:08 UTCJul 13, 13:45 UTC1h 37m
2026-07-13 SWA4853 DCA → STL Jul 13, 12:10 UTCJul 13, 13:45 UTC1h 35m
2026-07-13 SWA4496 - Jul 13, 02:25 UTCJul 13, 03:50 UTC1h 25m
2026-07-12 SWA2657 MCO → MDW Jul 12, 23:00 UTCJul 13, 01:20 UTC2h 20m
2026-07-12 SWA335 - Jul 12, 19:55 UTCJul 12, 21:30 UTC1h 35m
2026-07-12 SWA335 - Jul 12, 17:45 UTCJul 12, 18:15 UTC30m
2026-07-12 SWA894 - Jul 12, 15:20 UTCJul 12, 16:30 UTC1h 10m
2026-07-12 SWA898 - Jul 12, 12:35 UTCJul 12, 13:50 UTC1h 15m
2026-07-12 SWA898 BWI → CHS Jul 12, 12:31 UTCJul 12, 13:51 UTC1h 20m
2026-07-12 SWA2141 - Jul 12, 10:10 UTCJul 12, 11:05 UTC55m
2026-07-12 SWA2141 ISP → BWI Jul 12, 10:08 UTCJul 12, 11:00 UTC52m
2026-07-12 SWA4840 - Jul 12, 01:20 UTCJul 12, 03:30 UTC2h 10m
2026-07-12 SWA4840 MCO → ISP Jul 12, 01:19 UTCJul 12, 03:26 UTC2h 7m
2026-07-11 SWA2820 - Jul 11, 21:25 UTCJul 12, 00:10 UTC2h 45m
2026-07-11 SWA2820 MDW → MCO Jul 11, 21:22 UTCJul 12, 00:07 UTC2h 46m
2026-07-11 SWA2820 MSP → MDW Jul 11, 18:55 UTCJul 11, 19:55 UTC1h 0m
2026-07-11 SWA2820 DEN → MSP Jul 11, 16:25 UTCJul 11, 17:55 UTC1h 30m
2026-07-11 SWA4118 - Jul 11, 14:15 UTCJul 11, 14:50 UTC35m
2026-07-11 SWA4118 MTJ → DEN Jul 11, 14:07 UTCJul 11, 14:52 UTC45m
2026-07-11 SWA9010 - Jul 11, 02:25 UTCJul 11, 02:55 UTC30m
2026-07-10 SWA2519 PDX → DEN Jul 10, 22:00 UTCJul 11, 00:55 UTC2h 55m
2026-07-10 SWA2310 PHX → PDX Jul 10, 19:00 UTCJul 10, 21:10 UTC2h 11m
2026-07-10 SWA2310 PHX → PDX Jul 10, 18:56 UTCJul 10, 21:13 UTC2h 17m
2026-07-10 SWA2310 LAS → PHX Jul 10, 17:10 UTCJul 10, 17:55 UTC45m
2026-07-10 SWA2310 - Jul 10, 15:15 UTCJul 10, 16:05 UTC50m
2026-07-10 SWA2310 - Jul 10, 12:50 UTCJul 10, 13:45 UTC55m
2026-07-10 SWA4876 SAN → TUS Jul 10, 03:04 UTCJul 10, 03:59 UTC55m
2026-07-10 SWA4876 - Jul 10, 03:05 UTCJul 10, 04:00 UTC55m
2026-07-10 SWA4485 - Jul 10, 00:50 UTCJul 10, 02:00 UTC1h 10m
2026-07-09 SWA4647 - Jul 9, 22:55 UTCJul 9, 23:45 UTC50m
2026-07-09 SWA4647 LAS → RNO Jul 9, 22:52 UTCJul 9, 23:45 UTC53m
2026-07-09 SWA380 - Jul 9, 19:50 UTCJul 9, 21:20 UTC1h 30m
2026-07-09 SWA380 - Jul 9, 18:10 UTCJul 9, 18:50 UTC40m
2026-07-09 SWA380 - Jul 9, 14:45 UTCJul 9, 17:15 UTC2h 30m
2026-07-09 SWA1434 - Jul 9, 11:25 UTCJul 9, 13:30 UTC2h 5m
2026-07-09 SWA1230 - Jul 9, 02:00 UTCJul 9, 02:45 UTC45m
2026-07-08 SWA1230 - Jul 8, 23:25 UTCJul 9, 01:20 UTC1h 55m
2026-07-08 SWA170 STL → PHX Jul 8, 19:10 UTCJul 8, 21:55 UTC2h 45m
2026-07-08 SWA1643 - Jul 8, 16:20 UTCJul 8, 18:00 UTC1h 40m
2026-07-08 SWA1643 HOU → STL Jul 8, 16:15 UTCJul 8, 17:48 UTC1h 33m

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 N437WN page for operator, model, and routing details .

Mode-S A53F20 frequently asked

What is Mode-S code A53F20?
A53F20 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N437WN.
Where is Mode-S A53F20 registered?
Mode-S code A53F20 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 A53F20 broadcasting right now?
No active broadcast right now. Last signal was 21m ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A53F20, octal 51237440, decimal 10,829,600.
What flights does A53F20 operate?
Mode-S A53F20 has broadcast 20 distinct callsigns, including SWA1396, SWA380, SWA2310, SWA1840, SWA881.