Apparatus

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sensors Mode-S transponder

A2D1BC

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N281AK · BOEING 737-900 · operated by ALASKA AIRLINES INC

Hex
A2D1BC
Octal
50550674
Decimal
10,670,524
Country
US
Tail
N281AK
Type
B739
No current signal · last broadcast Jul 26, 23:00 UTC
Flights observed
445
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Last known position

Most recent position reported by Mode-S A2D1BC.

Country allocation

The ICAO 24-bit address A2D1BC 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
ASA500 Alaska Airlines 6 2026-04-18
ASA299 - 6 2026-07-18
ASA685 Alaska Airlines 4 2026-06-09
ASA67 - 4 2026-07-05
ASA418 - 4 2026-07-12
ASA413 - 4 2026-07-06
ASA312 Alaska Airlines 4 2026-04-15
ASA9340 Alaska Airlines 3 2026-06-28
ASA705 - 3 2026-07-19
ASA673 Alaska Airlines 3 2026-05-31
ASA649 Alaska Airlines 3 2026-07-25
ASA635 Alaska Airlines 3 2026-05-01
ASA600 Alaska Airlines 3 2026-05-15
ASA539 Alaska Airlines 3 2026-06-09
ASA533 - 3 2026-07-19
ASA469 - 3 2026-06-23
ASA444 Alaska Airlines 3 2026-04-25
ASA421 Alaska Airlines 3 2026-07-20
ASA399 - 3 2026-07-17
ASA369 - 3 2026-07-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 ASA700 SEA → PHX Jul 26, 20:50 UTCJul 26, 23:00 UTC2h 10m
2026-07-26 ASA1468 SEA → LAX Jul 26, 17:35 UTCJul 26, 18:55 UTC1h 20m
2026-07-26 ASA682 SEA → DEN Jul 26, 14:55 UTCJul 26, 16:25 UTC1h 30m
2026-07-26 ASA1498 SEA → SFO Jul 26, 09:05 UTCJul 26, 12:10 UTC3h 5m
2026-07-26 ASA1532 SEA → LAX Jul 26, 02:20 UTCJul 26, 07:20 UTC5h 1m
2026-07-25 ASA731 SEA → SFO Jul 25, 22:00 UTCJul 26, 00:35 UTC2h 35m
2026-07-25 ASA731 SEA → SFO Jul 25, 21:59 UTCJul 26, 00:33 UTC2h 34m
2026-07-25 ASA621 PDX → SFO Jul 25, 18:55 UTCJul 25, 20:00 UTC1h 5m
2026-07-25 ASA621 PDX → SFO Jul 25, 18:54 UTCJul 25, 20:00 UTC1h 6m
2026-07-25 ASA485 CHS → SEA Jul 25, 15:30 UTCJul 25, 16:45 UTC1h 15m
2026-07-25 ASA649 LAS → PDX Jul 25, 01:35 UTCJul 25, 02:57 UTC1h 22m
2026-07-25 ASA649 LAS → PDX Jul 25, 01:20 UTCJul 25, 02:55 UTC1h 35m
2026-07-24 ASA1386 PVR → SFO Jul 24, 22:10 UTCJul 25, 00:10 UTC2h 0m
2026-07-24 ASA1567 ANC → PDX Jul 24, 17:20 UTCJul 24, 20:35 UTC3h 15m
2026-07-24 ASA1560 LAX → SJO Jul 24, 05:35 UTCJul 24, 08:55 UTC3h 20m
2026-07-23 ASA337 DAL → SFO Jul 23, 23:50 UTCJul 24, 03:50 UTC4h 0m
2026-07-23 ASA429 SEA → AUS Jul 23, 18:20 UTCJul 23, 21:55 UTC3h 35m
2026-07-23 ASA748 SFO → LAS Jul 23, 14:30 UTCJul 23, 16:30 UTC2h 0m
2026-07-22 ASA1406 LAX → ZLO Jul 22, 22:12 UTCJul 23, 00:03 UTC1h 51m
2026-07-22 ASA1360 SJD → LAX Jul 22, 19:00 UTCJul 23, 00:15 UTC5h 15m
2026-07-22 ASA717 SAN → SFO Jul 22, 14:45 UTCJul 22, 17:05 UTC2h 20m
2026-07-22 ASA31 JFK → SEA Jul 22, 02:20 UTCJul 22, 05:25 UTC3h 5m
2026-07-21 ASA211 SFO → JFK Jul 21, 04:50 UTCJul 21, 09:50 UTC5h 0m
2026-07-21 ASA1379 SFO → PVR Jul 21, 00:20 UTCJul 21, 02:20 UTC2h 0m
2026-07-20 ASA1379 SFO → PVR Jul 20, 23:48 UTCJul 21, 02:14 UTC2h 26m
2026-07-20 ASA421 PDX → SFO Jul 20, 18:10 UTCJul 20, 21:15 UTC3h 5m
2026-07-20 ASA421 PDX → SFO Jul 20, 18:07 UTCJul 20, 21:56 UTC3h 49m
2026-07-20 ASA519 SAT → SEA Jul 20, 12:20 UTCJul 20, 15:55 UTC3h 35m
2026-07-20 ASA520 SEA → SAT Jul 20, 06:15 UTCJul 20, 09:45 UTC3h 30m
2026-07-20 ASA501 PHX → SFO Jul 20, 01:10 UTCJul 20, 04:35 UTC3h 25m
2026-07-19 ASA497 - Jul 19, 21:00 UTCJul 19, 23:45 UTC2h 45m
2026-07-19 ASA497 SEA → MCI Jul 19, 20:59 UTCJul 19, 23:50 UTC2h 51m
2026-07-19 ASA705 OAK → SEA Jul 19, 17:54 UTCJul 19, 18:54 UTC1h 0m
2026-07-19 ASA705 - Jul 19, 17:40 UTCJul 19, 19:00 UTC1h 20m
2026-07-19 ASA533 SEA → OAK Jul 19, 14:53 UTCJul 19, 16:17 UTC1h 24m
2026-07-19 ASA533 SEA → OAK Jul 19, 14:35 UTCJul 19, 16:25 UTC1h 50m
2026-07-19 ASA591 CUN → SFO Jul 19, 03:45 UTCJul 19, 05:10 UTC1h 25m
2026-07-19 ASA504 OAK → SEA Jul 19, 00:55 UTCJul 19, 02:30 UTC1h 35m
2026-07-18 ASA1302 SEA → LAX Jul 18, 22:20 UTCJul 18, 23:30 UTC1h 10m
2026-07-18 ASA655 SEA → SFO Jul 18, 19:15 UTCJul 18, 21:00 UTC1h 45m
2026-07-18 ASA299 - Jul 18, 17:25 UTCJul 18, 17:35 UTC10m
2026-07-18 ASA299 EWR → SEA Jul 18, 11:47 UTCJul 18, 17:06 UTC5h 19m
2026-07-18 ASA299 - Jul 18, 11:50 UTCJul 18, 17:35 UTC5h 45m
2026-07-18 ASA1631 SFO → EWR Jul 18, 04:40 UTCJul 18, 09:10 UTC4h 30m
2026-07-17 ASA646 PDX → PHX Jul 17, 23:00 UTCJul 18, 02:25 UTC3h 25m
2026-07-17 ASA392 - Jul 17, 18:05 UTCJul 17, 21:30 UTC3h 25m
2026-07-17 ASA399 - Jul 17, 14:10 UTCJul 17, 16:04 UTC1h 55m
2026-07-17 ASA369 PDX → SAN Jul 17, 01:55 UTCJul 17, 04:10 UTC2h 15m
2026-07-16 ASA1402 - Jul 16, 22:15 UTCJul 17, 00:10 UTC1h 55m
2026-07-16 ASA467 SFO → ZIH Jul 16, 18:10 UTCJul 16, 20:49 UTC2h 40m

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 N281AK page for operator, model, and routing details .

Mode-S A2D1BC frequently asked

What is Mode-S code A2D1BC?
A2D1BC is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N281AK.
Where is Mode-S A2D1BC registered?
Mode-S code A2D1BC 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 A2D1BC broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 23:00 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A2D1BC, octal 50550674, decimal 10,670,524.
What flights does A2D1BC operate?
Mode-S A2D1BC has broadcast 20 distinct callsigns, including ASA500, ASA299, ASA685, ASA67, ASA418.