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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 1h ago
Flights observed
668
Distinct callsigns
20
Country
US
Last broadcast
1h ago

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
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
SWA1365 Southwest Airlines 4 2026-05-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 SWA4085 - Jul 13, 22:55 UTCJul 14, 01:00 UTC2h 5m
2026-07-13 SWA4085 - Jul 13, 21:30 UTCJul 13, 21:55 UTC25m
2026-07-13 SWA4870 PHX → TUS Jul 13, 20:10 UTCJul 13, 20:35 UTC25m
2026-07-13 SWA403 SLC → PHX Jul 13, 18:00 UTCJul 13, 19:20 UTC1h 20m
2026-07-13 SWA403 SLC → PHX Jul 13, 17:58 UTCJul 13, 19:14 UTC1h 16m
2026-07-13 SWA403 AUS → SLC Jul 13, 14:20 UTCJul 13, 16:40 UTC2h 20m
2026-07-13 SWA2093 - Jul 13, 12:20 UTCJul 13, 13:05 UTC45m
2026-07-13 SWA1195 - Jul 13, 03:20 UTCJul 13, 04:00 UTC40m
2026-07-12 SWA1195 - Jul 12, 23:30 UTCJul 13, 02:10 UTC2h 40m
2026-07-12 SWA2104 LAS → SAN Jul 12, 21:40 UTCJul 12, 22:30 UTC50m
2026-07-12 SWA2104 - Jul 12, 17:50 UTCJul 12, 19:50 UTC2h 0m
2026-07-12 SWA2104 - Jul 12, 15:35 UTCJul 12, 16:50 UTC1h 15m
2026-07-12 SWA163 - Jul 12, 12:10 UTCJul 12, 14:01 UTC1h 50m
2026-07-12 SWA858 - Jul 12, 02:25 UTCJul 12, 03:15 UTC50m
2026-07-11 SWA2621 - Jul 11, 23:25 UTCJul 12, 00:35 UTC1h 10m
2026-07-11 SWA2621 MDW → ELP Jul 11, 23:24 UTCJul 12, 00:31 UTC1h 7m
2026-07-11 SWA845 - Jul 11, 20:15 UTCJul 11, 22:15 UTC2h 0m
2026-07-11 SWA845 DEN → IND Jul 11, 20:15 UTCJul 11, 22:14 UTC1h 59m
2026-07-11 SWA845 SMF → DEN Jul 11, 17:20 UTCJul 11, 19:15 UTC1h 55m
2026-07-11 SWA845 BUR → SMF Jul 11, 15:20 UTCJul 11, 16:15 UTC55m
2026-07-11 SWA3035 OAK → BUR Jul 11, 13:19 UTCJul 11, 14:12 UTC53m
2026-07-11 SWA3035 OAK → BUR Jul 11, 13:20 UTCJul 11, 14:15 UTC55m
2026-07-11 SWA3205 PDX → OAK Jul 11, 06:40 UTCJul 11, 08:10 UTC1h 30m
2026-07-11 SWA3205 PDX → OAK Jul 11, 06:40 UTCJul 11, 08:05 UTC1h 25m
2026-07-11 SWA4368 OAK → PDX Jul 11, 04:54 UTCJul 11, 06:03 UTC1h 9m
2026-07-11 SWA4368 OAK → PDX Jul 11, 04:55 UTCJul 11, 06:05 UTC1h 10m
2026-07-11 SWA807 - Jul 11, 02:00 UTCJul 11, 02:50 UTC50m
2026-07-10 SWA461 - Jul 10, 21:15 UTCJul 11, 01:05 UTC3h 50m
2026-07-10 SWA4004 TPA → BNA Jul 10, 18:20 UTCJul 10, 20:00 UTC1h 40m
2026-07-10 SWA3986 - Jul 10, 15:15 UTCJul 10, 17:10 UTC1h 55m
2026-07-10 SWA2973 MSP → STL Jul 10, 12:55 UTCJul 10, 13:55 UTC1h 0m
2026-07-10 SWA2677 DEN → MSP Jul 10, 03:16 UTCJul 10, 04:48 UTC1h 33m
2026-07-10 SWA2677 DEN → MSP Jul 10, 03:20 UTCJul 10, 04:50 UTC1h 30m
2026-07-10 SWA2519 - Jul 10, 01:35 UTCJul 10, 01:55 UTC20m
2026-07-09 SWA2519 - Jul 9, 23:40 UTCJul 10, 01:05 UTC1h 25m
2026-07-09 SWA2519 PDX → DEN Jul 9, 23:40 UTCJul 10, 01:41 UTC2h 1m
2026-07-09 SWA2310 - Jul 9, 18:55 UTCJul 9, 21:15 UTC2h 20m
2026-07-09 SWA2492 - Jul 9, 17:00 UTCJul 9, 18:00 UTC1h 0m
2026-07-09 SWA276 LAS → LGB Jul 9, 15:15 UTCJul 9, 15:55 UTC40m
2026-07-09 SWA276 - Jul 9, 11:35 UTCJul 9, 14:05 UTC2h 30m
2026-07-09 SWA4758 - Jul 9, 04:15 UTCJul 9, 05:35 UTC1h 20m
2026-07-08 SWA2456 LGA → DEN Jul 8, 21:35 UTCJul 9, 02:05 UTC4h 30m
2026-07-08 SWA2803 - Jul 8, 18:35 UTCJul 8, 20:15 UTC1h 40m
2026-07-08 SWA3513 - Jul 8, 13:40 UTCJul 8, 17:15 UTC3h 35m
2026-07-08 SWA4265 - Jul 8, 04:05 UTCJul 8, 05:05 UTC1h 0m
2026-07-08 SWA342 - Jul 8, 02:25 UTCJul 8, 03:25 UTC1h 0m
2026-07-08 SWA342 SNA → SJC Jul 8, 02:24 UTCJul 8, 03:20 UTC56m
2026-07-08 SWA342 - Jul 8, 00:50 UTCJul 8, 01:30 UTC40m
2026-07-07 SWA2012 PDX → OAK Jul 7, 22:05 UTCJul 7, 23:45 UTC1h 40m
2026-07-07 SWA2012 PDX → OAK Jul 7, 20:05 UTCJul 7, 21:10 UTC1h 5m

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 1h ago.
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, SWA1679, SWA1222, SWA1642.