Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A5540C

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N442WN · BOEING 737-700 · operated by SOUTHWEST AIRLINES CO

Hex
A5540C
Octal
51252014
Decimal
10,834,956
Country
US
Tail
N442WN
Type
B737
Broadcasting now · callsign SWA1712 · 32,850 ft
Flights observed
720
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Current position

A5540C is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A5540C 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
SWA155 - 7 2026-04-17
SWA1479 Southwest Airlines 7 2026-04-24
SWA311 Southwest Airlines 6 2026-06-08
SWA667 - 5 2026-07-19
SWA372 Southwest Airlines 5 2026-06-30
SWA2250 Southwest Airlines 5 2026-07-23
SWA2137 Southwest Airlines 5 2026-05-15
SWA1753 - 5 2026-07-17
SWA882 - 4 2026-06-20
SWA669 Southwest Airlines 4 2026-06-07
SWA4745 Southwest Airlines 4 2026-06-29
SWA4560 Southwest Airlines 4 2026-06-29
SWA4492 Southwest Airlines 4 2026-04-24
SWA3702 Southwest Airlines 4 2026-06-17
SWA3639 Southwest Airlines 4 2026-05-06
SWA3335 Southwest Airlines 4 2026-05-15
SWA2664 - 4 2026-06-20
SWA26 Southwest Airlines 4 2026-05-24
SWA2599 Southwest Airlines 4 2026-06-21
SWA245 Southwest Airlines 4 2026-05-04

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SWA3231 CVG → MDW Jul 26, 22:55 UTCJul 26, 23:00 UTC5m
2026-07-26 SWA4769 ALB → FLL Jul 26, 19:20 UTCJul 26, 21:30 UTC2h 10m
2026-07-26 SWA1204 OAK → LAX Jul 26, 17:40 UTCJul 26, 18:25 UTC45m
2026-07-26 SWA2203 STL → TPA Jul 26, 13:15 UTCJul 26, 15:30 UTC2h 15m
2026-07-26 SWA2203 STL → TPA Jul 26, 13:15 UTCJul 26, 15:25 UTC2h 10m
2026-07-26 SWA2108 BWI → BOS Jul 26, 10:10 UTCJul 26, 12:05 UTC1h 55m
2026-07-26 SWA241 SAN → PHX Jul 26, 01:35 UTCJul 26, 03:35 UTC2h 0m
2026-07-25 SWA731 SJD → DEN Jul 25, 22:35 UTCJul 25, 23:45 UTC1h 10m
2026-07-25 SWA731 SJD → DEN Jul 25, 21:06 UTCJul 25, 23:39 UTC2h 34m
2026-07-25 SWA1480 ONT → SJC Jul 25, 16:35 UTCJul 25, 18:40 UTC2h 5m
2026-07-25 SWA1480 ONT → SJC Jul 25, 16:33 UTCJul 25, 19:55 UTC3h 22m
2026-07-25 SWA3809 MCO → AUS Jul 25, 13:55 UTCJul 25, 15:15 UTC1h 20m
2026-07-25 SWA3809 MCO → AUS Jul 25, 13:50 UTCJul 25, 15:08 UTC1h 18m
2026-07-25 SWA3597 MCO → PVD Jul 25, 11:35 UTCJul 25, 12:35 UTC1h 0m
2026-07-25 SWA353 SLC → DEN Jul 25, 03:20 UTCJul 25, 05:15 UTC1h 55m
2026-07-25 SWA353 SLC → DEN Jul 25, 00:10 UTCJul 25, 02:30 UTC2h 20m
2026-07-24 SWA2979 SEA → OAK Jul 24, 22:05 UTCJul 24, 23:05 UTC1h 0m
2026-07-24 SWA2979 SEA → OAK Jul 24, 22:03 UTCJul 24, 23:05 UTC1h 2m
2026-07-24 SWA2052 PDX → OAK Jul 24, 20:20 UTCJul 24, 21:00 UTC40m
2026-07-24 SWA2052 PDX → OAK Jul 24, 20:16 UTCJul 24, 21:05 UTC49m
2026-07-24 SWA1642 OAK → BLI Jul 24, 18:25 UTCJul 24, 19:10 UTC45m
2026-07-24 SWA1642 OAK → BLI Jul 24, 14:10 UTCJul 24, 16:35 UTC2h 25m
2026-07-24 SWA1769 DSM → DEN Jul 24, 11:25 UTCJul 24, 12:46 UTC1h 21m
2026-07-24 SWA4279 SJC → LAS Jul 24, 03:30 UTCJul 24, 04:20 UTC50m
2026-07-24 SWA345 DEN → LAS Jul 24, 01:40 UTCJul 24, 02:35 UTC55m
2026-07-23 SWA345 DEN → LAS Jul 23, 23:20 UTCJul 24, 00:45 UTC1h 25m
2026-07-23 SWA345 DEN → LAS Jul 23, 19:40 UTCJul 23, 22:15 UTC2h 35m
2026-07-23 SWA3626 BWI → MKE Jul 23, 16:35 UTCJul 23, 17:35 UTC1h 0m
2026-07-23 SWA3626 BWI → MKE Jul 23, 13:55 UTCJul 23, 15:45 UTC1h 50m
2026-07-23 SWA2250 OAK → LAS Jul 23, 04:55 UTCJul 23, 06:20 UTC1h 25m
2026-07-23 SWA2250 OAK → LAS Jul 23, 04:55 UTCJul 23, 06:17 UTC1h 22m
2026-07-23 SWA2250 OAK → LAS Jul 23, 02:35 UTCJul 23, 04:05 UTC1h 30m
2026-07-23 SWA819 SJC → SEA Jul 23, 00:00 UTCJul 23, 01:05 UTC1h 5m
2026-07-22 SWA4540 LAS → SAN Jul 22, 22:25 UTCJul 22, 23:10 UTC45m
2026-07-22 SWA4540 LAS → SAN Jul 22, 22:20 UTCJul 22, 23:10 UTC50m
2026-07-22 SWA2235 LAX → SJC Jul 22, 18:55 UTCJul 22, 21:20 UTC2h 25m
2026-07-22 SWA748 PHX → RNO Jul 22, 16:55 UTCJul 22, 17:55 UTC1h 0m
2026-07-22 SWA4118 BNA → JAX Jul 22, 14:35 UTCJul 22, 15:00 UTC25m
2026-07-22 SWA1649 - Jul 22, 01:00 UTCJul 22, 01:30 UTC30m
2026-07-21 SWA515 PVR → DEN Jul 21, 17:27 UTCJul 21, 20:13 UTC2h 47m
2026-07-21 SWA108 - Jul 21, 14:25 UTCJul 21, 15:30 UTC1h 5m
2026-07-21 SWA108 HOU → PVR Jul 21, 14:23 UTCJul 21, 16:14 UTC1h 51m
2026-07-21 SWA1 DAL → HOU Jul 21, 12:15 UTCJul 21, 13:00 UTC45m
2026-07-21 SWA1 DAL → HOU Jul 21, 12:11 UTCJul 21, 12:59 UTC49m
2026-07-21 SWA1523 ATL → LGA Jul 21, 02:50 UTCJul 21, 04:20 UTC1h 30m
2026-07-21 SWA1188 - Jul 21, 00:45 UTCJul 21, 01:55 UTC1h 10m
2026-07-20 SWA1188 DCA → OKC Jul 20, 21:25 UTCJul 20, 23:55 UTC2h 29m
2026-07-20 SWA1188 MCO → DCA Jul 20, 18:05 UTCJul 20, 20:05 UTC2h 0m
2026-07-20 SWA215 ATL → MCO Jul 20, 15:45 UTCJul 20, 16:45 UTC1h 0m
2026-07-20 SWA4987 SAN → OAK Jul 20, 13:45 UTCJul 20, 14:45 UTC1h 0m

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 N442WN page for operator, model, and routing details .

Mode-S A5540C frequently asked

What is Mode-S code A5540C?
A5540C is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N442WN.
Where is Mode-S A5540C registered?
Mode-S code A5540C 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 A5540C broadcasting right now?
Yes. Mode-S A5540C is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A5540C, octal 51252014, decimal 10,834,956.
What flights does A5540C operate?
Mode-S A5540C has broadcast 20 distinct callsigns, including SWA155, SWA1479, SWA311, SWA667, SWA372.