Apparatus

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sensors Mode-S transponder

A25B3F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N251AK · BOEING 737-900 · operated by ALASKA AIRLINES INC

Hex
A25B3F
Octal
50455477
Decimal
10,640,191
Country
US
Tail
N251AK
Type
B739
No current signal · last broadcast Jul 26, 20:20 UTC
Flights observed
396
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:20 UTC

Last known position

Most recent position reported by Mode-S A25B3F.

Country allocation

The ICAO 24-bit address A25B3F 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
ASA450 - 6 2026-07-07
ASA703 Alaska Airlines 5 2026-05-26
ASA62 Alaska Airlines 5 2026-07-25
ASA306 - 5 2026-06-26
ASA9411 Alaska Airlines 4 2026-06-08
ASA78 - 4 2026-06-24
ASA716 Alaska Airlines 4 2026-05-07
ASA458 Alaska Airlines 4 2026-05-07
ASA379 - 4 2026-04-13
ASA352 Alaska Airlines 4 2026-07-25
ASA250 Alaska Airlines 4 2026-07-22
ASA1337 Alaska Airlines 4 2026-07-09
ASA9341 Alaska Airlines 3 2026-07-17
ASA729 Alaska Airlines 3 2026-05-30
ASA709 Alaska Airlines 3 2026-05-30
ASA647 - 3 2026-07-16
ASA604 Alaska Airlines 3 2026-06-14
ASA602 - 3 2026-07-10
ASA473 - 3 2026-06-16
ASA415 - 3 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 ASA695 SJC → PDX Jul 26, 18:20 UTCJul 26, 20:20 UTC2h 0m
2026-07-26 ASA679 DEN → PDX Jul 26, 15:05 UTCJul 26, 16:30 UTC1h 25m
2026-07-26 ASA539 SAN → SEA Jul 26, 01:13 UTCJul 26, 02:48 UTC1h 35m
2026-07-26 ASA539 SAN → SEA Jul 26, 01:00 UTCJul 26, 02:50 UTC1h 50m
2026-07-25 ASA62 KTN → SEA Jul 25, 21:35 UTCJul 25, 23:05 UTC1h 30m
2026-07-25 ASA62 KTN → SEA Jul 25, 19:55 UTCJul 25, 20:15 UTC20m
2026-07-25 ASA62 KTN → SEA Jul 25, 18:45 UTCJul 25, 19:00 UTC15m
2026-07-25 ASA62 KTN → SEA Jul 25, 15:20 UTCJul 25, 16:30 UTC1h 10m
2026-07-25 ASA62 KTN → SEA Jul 25, 15:16 UTCJul 25, 16:39 UTC1h 23m
2026-07-25 ASA352 ANC → SEA Jul 25, 02:15 UTCJul 25, 03:10 UTC55m
2026-07-25 ASA352 ANC → SEA Jul 25, 02:19 UTCJul 25, 03:01 UTC42m
2026-07-25 ASA351 LAX → SEA Jul 25, 00:00 UTCJul 25, 00:45 UTC45m
2026-07-24 ASA83 SEA → ANC Jul 24, 18:55 UTCJul 24, 22:10 UTC3h 15m
2026-07-24 ASA83 SEA → ANC Jul 24, 18:52 UTCJul 24, 22:00 UTC3h 8m
2026-07-24 ASA281 EWR → SEA Jul 24, 12:20 UTCJul 24, 16:55 UTC4h 35m
2026-07-24 ASA382 SEA → BNA Jul 24, 06:30 UTCJul 24, 10:10 UTC3h 40m
2026-07-24 ASA532 LAX → PDX Jul 24, 01:05 UTCJul 24, 04:30 UTC3h 25m
2026-07-23 ASA527 SNA → SEA Jul 23, 21:05 UTCJul 23, 23:45 UTC2h 40m
2026-07-23 ASA798 SEA → LAS Jul 23, 17:25 UTCJul 23, 19:30 UTC2h 5m
2026-07-23 ASA505 SNA → SEA Jul 23, 13:15 UTCJul 23, 15:35 UTC2h 20m
2026-07-23 ASA1431 BOS → SEA Jul 23, 02:00 UTCJul 23, 04:15 UTC2h 15m
2026-07-22 ASA1312 PDX → SAN Jul 22, 22:30 UTCJul 23, 00:40 UTC2h 10m
2026-07-22 ASA251 GEG → PDX Jul 22, 20:10 UTCJul 22, 20:55 UTC45m
2026-07-22 ASA250 PDX → GEG Jul 22, 18:15 UTCJul 22, 19:00 UTC45m
2026-07-22 ASA1626 DEN → PDX Jul 22, 14:20 UTCJul 22, 15:45 UTC1h 25m
2026-07-22 ASA1626 DEN → PDX Jul 22, 14:16 UTCJul 22, 16:29 UTC2h 13m
2026-07-22 ASA752 SEA → PSP Jul 22, 10:20 UTCJul 22, 12:10 UTC1h 50m
2026-07-22 ASA752 SEA → PSP Jul 22, 07:33 UTCJul 22, 11:58 UTC4h 25m
2026-07-22 ASA661 PHX → PAE Jul 22, 02:10 UTCJul 22, 05:20 UTC3h 10m
2026-07-21 ASA402 - Jul 21, 21:15 UTCJul 22, 00:15 UTC3h 0m
2026-07-21 ASA53 EWR → PDX Jul 21, 14:50 UTCJul 21, 19:30 UTC4h 40m
2026-07-20 ASA287 - Jul 20, 23:55 UTCJul 21, 04:55 UTC5h 0m
2026-07-20 ASA477 SEA → EWR Jul 20, 17:55 UTCJul 20, 22:10 UTC4h 15m
2026-07-20 ASA554 PDX → ORD Jul 20, 12:20 UTCJul 20, 15:35 UTC3h 15m
2026-07-20 ASA553 SEA → OKC Jul 20, 02:30 UTCJul 20, 05:30 UTC3h 0m
2026-07-19 ASA425 PHX → SEA Jul 19, 22:15 UTCJul 20, 00:35 UTC2h 20m
2026-07-19 ASA747 - Jul 19, 18:25 UTCJul 19, 20:55 UTC2h 30m
2026-07-19 ASA1572 - Jul 19, 14:10 UTCJul 19, 17:10 UTC3h 0m
2026-07-19 ASA478 SEA → LAS Jul 19, 01:45 UTCJul 19, 03:55 UTC2h 10m
2026-07-18 ASA618 LAS → SEA Jul 18, 20:00 UTCJul 18, 23:35 UTC3h 35m
2026-07-18 ASA618 LAS → SEA Jul 18, 15:20 UTCJul 18, 18:40 UTC3h 20m
2026-07-17 ASA9341 SNA → SFO Jul 17, 20:29 UTCJul 17, 20:40 UTC10m
2026-07-17 ASA9341 SNA → SFO Jul 17, 16:55 UTCJul 17, 20:40 UTC3h 45m
2026-07-17 ASA9341 SNA → SFO Jul 17, 16:31 UTCJul 17, 20:11 UTC3h 40m
2026-07-16 ASA647 SEA → STL Jul 16, 23:55 UTCJul 17, 03:20 UTC3h 25m
2026-07-16 ASA415 DFW → SEA Jul 16, 18:35 UTCJul 16, 21:41 UTC3h 6m
2026-07-16 ASA415 DFW → SEA Jul 16, 18:25 UTCJul 16, 22:00 UTC3h 35m
2026-07-16 ASA414 SEA → DFW Jul 16, 13:15 UTCJul 16, 16:40 UTC3h 25m
2026-07-16 ASA1509 FAI → SEA Jul 16, 08:36 UTCJul 16, 11:23 UTC2h 47m
2026-07-16 ASA1509 - Jul 16, 08:30 UTCJul 16, 11:30 UTC3h 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 N251AK page for operator, model, and routing details .

Mode-S A25B3F frequently asked

What is Mode-S code A25B3F?
A25B3F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N251AK.
Where is Mode-S A25B3F registered?
Mode-S code A25B3F 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 A25B3F broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:20 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A25B3F, octal 50455477, decimal 10,640,191.
What flights does A25B3F operate?
Mode-S A25B3F has broadcast 20 distinct callsigns, including ASA450, ASA703, ASA62, ASA306, ASA9411.