Apparatus

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sensors Mode-S transponder

AD21BC

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N945WN · BOEING 737-700 · operated by SOUTHWEST AIRLINES CO

Hex
AD21BC
Octal
53220674
Decimal
11,346,364
Country
US
Tail
N945WN
Type
B737
No current signal · last broadcast Jul 26, 22:45 UTC
Flights observed
775
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:45 UTC

Last known position

Most recent position reported by Mode-S AD21BC.

Country allocation

The ICAO 24-bit address AD21BC 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
SWA487 Southwest Airlines 7 2026-05-27
SWA8 Southwest Airlines 6 2026-06-18
SWA2121 - 6 2026-07-17
SWA1679 - 6 2026-06-24
SWA1222 - 6 2026-06-28
SWA1642 Southwest Airlines 5 2026-06-05
SWA1011 Southwest Airlines 5 2026-05-08
SWA874 Southwest Airlines 4 2026-05-26
SWA845 - 4 2026-07-11
SWA556 - 4 2026-06-24
SWA467 - 4 2026-07-05
SWA4018 Southwest Airlines 4 2026-05-06
SWA371 - 4 2026-06-21
SWA3538 - 4 2026-07-04
SWA3026 Southwest Airlines 4 2026-05-06
SWA276 - 4 2026-07-09
SWA2719 Southwest Airlines 4 2026-05-06
SWA2556 Southwest Airlines 4 2026-05-13
SWA2278 Southwest Airlines 4 2026-04-28
SWA1426 - 4 2026-06-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SWA1402 LAS → BLI Jul 26, 20:05 UTCJul 26, 22:40 UTC2h 35m
2026-07-26 SWA2114 PDX → SJC Jul 26, 15:25 UTCJul 26, 18:50 UTC3h 25m
2026-07-26 SWA2114 PDX → SJC Jul 26, 13:10 UTCJul 26, 14:35 UTC1h 25m
2026-07-26 SWA290 ONT → AUS Jul 26, 03:55 UTCJul 26, 05:15 UTC1h 20m
2026-07-26 SWA290 ONT → AUS Jul 26, 01:00 UTCJul 26, 03:05 UTC2h 5m
2026-07-25 SWA290 ONT → AUS Jul 25, 21:30 UTCJul 25, 23:35 UTC2h 5m
2026-07-25 SWA4411 CMH → DCA Jul 25, 17:10 UTCJul 25, 19:40 UTC2h 30m
2026-07-25 SWA4411 CMH → DCA Jul 25, 17:05 UTCJul 25, 19:35 UTC2h 30m
2026-07-25 SWA4003 OAK → PHX Jul 25, 13:30 UTCJul 25, 15:50 UTC2h 20m
2026-07-25 SWA4003 OAK → PHX Jul 25, 13:29 UTCJul 25, 15:46 UTC2h 18m
2026-07-25 SWA2976 STL → LGA Jul 25, 11:15 UTCJul 25, 12:20 UTC1h 5m
2026-07-25 SWA2976 STL → LGA Jul 25, 11:14 UTCJul 25, 12:16 UTC1h 2m
2026-07-25 SWA4756 BNA → MSY Jul 25, 01:45 UTCJul 25, 02:30 UTC45m
2026-07-24 SWA3129 ALB → BWI Jul 24, 22:45 UTCJul 25, 00:30 UTC1h 45m
2026-07-24 SWA3129 ALB → BWI Jul 24, 19:35 UTCJul 24, 21:50 UTC2h 15m
2026-07-24 SWA4651 TPA → MSY Jul 24, 16:00 UTCJul 24, 18:10 UTC2h 10m
2026-07-24 SWA4289 MCO → SJU Jul 24, 13:25 UTCJul 24, 14:40 UTC1h 15m
2026-07-24 SWA3388 ABQ → MDW Jul 24, 10:50 UTCJul 24, 11:20 UTC30m
2026-07-24 SWA1125 LGB → SJC Jul 24, 01:45 UTCJul 24, 02:55 UTC1h 10m
2026-07-23 SWA4616 DAL → DEN Jul 23, 23:35 UTCJul 24, 00:55 UTC1h 20m
2026-07-23 SWA4479 ALB → BWI Jul 23, 21:05 UTCJul 23, 22:35 UTC1h 30m
2026-07-23 SWA4479 ALB → BWI Jul 23, 21:01 UTCJul 23, 22:34 UTC1h 33m
2026-07-23 SWA1185 DEN → LGA Jul 23, 18:10 UTCJul 23, 19:10 UTC1h 0m
2026-07-23 SWA1429 BHM → MDW Jul 23, 16:15 UTCJul 23, 17:15 UTC1h 0m
2026-07-23 SWA222 ATL → STL Jul 23, 15:00 UTCJul 23, 15:05 UTC5m
2026-07-23 SWA222 ATL → STL Jul 23, 12:40 UTCJul 23, 15:05 UTC2h 25m
2026-07-23 SWA222 ATL → STL Jul 23, 12:40 UTCJul 23, 14:45 UTC2h 5m
2026-07-23 SWA2049 BNA → PHL Jul 23, 10:40 UTCJul 23, 11:30 UTC50m
2026-07-23 SWA2049 BNA → PHL Jul 23, 10:37 UTCJul 23, 11:29 UTC52m
2026-07-23 SWA3869 DEN → SAN Jul 23, 01:30 UTCJul 23, 02:25 UTC55m
2026-07-22 SWA3869 DEN → SAN Jul 22, 22:50 UTCJul 23, 00:05 UTC1h 15m
2026-07-22 SWA3869 DEN → SAN Jul 22, 20:50 UTCJul 22, 21:50 UTC1h 0m
2026-07-22 SWA1430 DEN → PDX Jul 22, 18:40 UTCJul 22, 19:45 UTC1h 5m
2026-07-22 SWA1430 DEN → PDX Jul 22, 18:35 UTCJul 22, 19:38 UTC1h 3m
2026-07-22 SWA1430 DEN → PDX Jul 22, 15:45 UTCJul 22, 17:20 UTC1h 35m
2026-07-22 SWA1106 SAN → SJC Jul 22, 12:35 UTCJul 22, 14:40 UTC2h 5m
2026-07-22 SWA4657 - Jul 22, 11:10 UTCJul 22, 11:35 UTC25m
2026-07-21 SWA1003 - Jul 21, 15:30 UTCJul 21, 16:25 UTC55m
2026-07-21 SWA1003 BWI → MHT Jul 21, 15:25 UTCJul 21, 16:26 UTC1h 1m
2026-07-21 SWA1899 MDW → DCA Jul 21, 12:30 UTCJul 21, 13:40 UTC1h 10m
2026-07-21 SWA1899 MDW → DCA Jul 21, 12:28 UTCJul 21, 13:33 UTC1h 5m
2026-07-21 SWA4563 - Jul 21, 02:00 UTCJul 21, 02:35 UTC35m
2026-07-21 SWA4563 BNA → GSP Jul 21, 01:57 UTCJul 21, 02:45 UTC48m
2026-07-20 SWA1428 SJC → SAN Jul 20, 23:10 UTCJul 21, 00:30 UTC1h 20m
2026-07-20 SWA2699 ATL → DCA Jul 20, 20:40 UTCJul 20, 22:10 UTC1h 30m
2026-07-20 SWA527 - Jul 20, 17:45 UTCJul 20, 19:15 UTC1h 30m
2026-07-20 SWA3931 - Jul 20, 15:10 UTCJul 20, 16:45 UTC1h 35m
2026-07-20 SWA3931 - Jul 20, 12:55 UTCJul 20, 14:00 UTC1h 5m
2026-07-20 SWA3931 - Jul 20, 12:40 UTCJul 20, 12:50 UTC10m
2026-07-20 SWA3438 PVD → MCO Jul 20, 10:30 UTCJul 20, 10:55 UTC25m

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 N945WN page for operator, model, and routing details .

Mode-S AD21BC frequently asked

What is Mode-S code AD21BC?
AD21BC is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N945WN.
Where is Mode-S AD21BC registered?
Mode-S code AD21BC 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 AD21BC broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AD21BC, octal 53220674, decimal 11,346,364.
What flights does AD21BC operate?
Mode-S AD21BC has broadcast 20 distinct callsigns, including SWA487, SWA8, SWA2121, SWA1679, SWA1222.