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sensors Mode-S transponder

A5939C

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N459AS · BOEING 737-900 · operated by ALASKA AIRLINES INC

Hex
A5939C
Octal
51311634
Decimal
10,851,228
Country
US
Tail
N459AS
Type
B739
No current signal · last broadcast Jul 26, 22:30 UTC
Flights observed
400
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:30 UTC

Last known position

Most recent position reported by Mode-S A5939C.

Country allocation

The ICAO 24-bit address A5939C 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
ASA271 - 6 2026-07-16
ASA18 - 6 2026-07-05
ASA270 Alaska Airlines 5 2026-06-04
ASA1332 Alaska Airlines 5 2026-06-05
ASA787 - 4 2026-07-07
ASA758 - 4 2026-06-16
ASA719 Alaska Airlines 4 2026-06-09
ASA618 - 4 2026-07-01
ASA614 Alaska Airlines 4 2026-05-08
ASA500 Alaska Airlines 4 2026-05-15
ASA488 Alaska Airlines 4 2026-06-17
ASA483 Alaska Airlines 4 2026-05-26
ASA17 - 4 2026-07-06
ASA114 Alaska Airlines 4 2026-04-15
ASA627 - 3 2026-06-26
ASA563 - 3 2026-07-02
ASA529 Alaska Airlines 3 2026-06-02
ASA503 - 3 2026-07-14
ASA49 Alaska Airlines 3 2026-06-07
ASA392 - 3 2026-07-10

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 ASA223 SEA → FAI Jul 26, 21:40 UTCJul 26, 22:30 UTC50m
2026-07-26 ASA623 PVR → SFO Jul 26, 14:30 UTCJul 26, 18:55 UTC4h 25m
2026-07-26 ASA416 SFO → DAL Jul 26, 01:15 UTCJul 26, 04:50 UTC3h 35m
2026-07-25 ASA415 LAX → SEA Jul 25, 18:35 UTCJul 25, 22:10 UTC3h 35m
2026-07-25 ASA414 SFO → LAS Jul 25, 13:15 UTCJul 25, 16:40 UTC3h 25m
2026-07-24 ASA205 SAN → SEA Jul 24, 23:30 UTCJul 25, 04:50 UTC5h 20m
2026-07-24 ASA222 SAN → AUS Jul 24, 16:40 UTCJul 24, 17:15 UTC35m
2026-07-24 ASA222 SAN → AUS Jul 24, 16:38 UTCJul 24, 21:53 UTC5h 15m
2026-07-24 ASA203 SEA → SJC Jul 24, 02:55 UTCJul 24, 03:35 UTC40m
2026-07-23 ASA245 SEA → OGG Jul 23, 15:55 UTCJul 23, 16:45 UTC50m
2026-07-23 ASA206 PDX → SFO Jul 23, 07:57 UTCJul 23, 12:38 UTC4h 41m
2026-07-23 ASA353 ORD → SEA Jul 23, 01:10 UTCJul 23, 01:55 UTC45m
2026-07-22 ASA1600 SFO → LAS Jul 22, 22:05 UTCJul 22, 23:05 UTC1h 0m
2026-07-22 ASA1428 SFO → SJD Jul 22, 19:20 UTCJul 22, 20:50 UTC1h 30m
2026-07-22 ASA348 SEA → IAD Jul 22, 13:10 UTCJul 22, 17:50 UTC4h 40m
2026-07-21 ASA727 PDX → LAS Jul 21, 23:40 UTCJul 22, 03:50 UTC4h 10m
2026-07-21 ASA676 SEA → LAS Jul 21, 19:49 UTCJul 21, 21:22 UTC1h 33m
2026-07-21 ASA1628 PDX → LAS Jul 21, 16:20 UTCJul 21, 18:15 UTC1h 55m
2026-07-21 ASA1628 PDX → LAS Jul 21, 16:20 UTCJul 21, 18:04 UTC1h 44m
2026-07-20 ASA301 LIH → SJC Jul 20, 22:40 UTCJul 21, 03:45 UTC5h 4m
2026-07-20 ASA295 SEA → MCO Jul 20, 14:55 UTCJul 20, 20:45 UTC5h 50m
2026-07-20 ASA1368 - Jul 20, 02:40 UTCJul 20, 04:50 UTC2h 10m
2026-07-20 ASA1523 LAX → SJO Jul 20, 00:15 UTCJul 20, 01:15 UTC1h 0m
2026-07-19 ASA680 SEA → SFO Jul 19, 20:45 UTCJul 19, 22:40 UTC1h 55m
2026-07-19 ASA1468 SMF → SEA Jul 19, 17:40 UTCJul 19, 19:00 UTC1h 20m
2026-07-19 ASA682 SEA → SMF Jul 19, 14:50 UTCJul 19, 16:20 UTC1h 30m
2026-07-19 ASA259 KOA → SEA Jul 19, 07:39 UTCJul 19, 12:26 UTC4h 47m
2026-07-19 ASA259 - Jul 19, 07:25 UTCJul 19, 07:40 UTC15m
2026-07-19 ASA238 - Jul 19, 04:45 UTCJul 19, 05:00 UTC15m
2026-07-18 ASA238 - Jul 18, 23:35 UTCJul 19, 00:20 UTC45m
2026-07-18 ASA9360 MCO → SAN Jul 18, 15:55 UTCJul 18, 21:10 UTC5h 15m
2026-07-18 ASA394 SEA → MCO Jul 18, 05:05 UTCJul 18, 10:10 UTC5h 5m
2026-07-17 ASA356 EWR → SEA Jul 17, 20:50 UTCJul 18, 02:14 UTC5h 25m
2026-07-17 ASA239 LIH → SJC Jul 17, 14:15 UTCJul 17, 18:55 UTC4h 40m
2026-07-17 ASA550 DFW → SEA Jul 17, 02:34 UTCJul 17, 06:00 UTC3h 25m
2026-07-17 ASA550 DFW → SEA Jul 17, 02:35 UTCJul 17, 05:59 UTC3h 24m
2026-07-17 ASA380 - Jul 17, 00:45 UTCJul 17, 00:50 UTC5m
2026-07-16 ASA380 SAN → DFW Jul 16, 22:01 UTCJul 17, 00:28 UTC2h 27m
2026-07-16 ASA380 - Jul 16, 22:05 UTCJul 17, 00:50 UTC2h 45m
2026-07-16 ASA1394 - Jul 16, 18:05 UTCJul 16, 20:19 UTC2h 15m
2026-07-16 ASA511 - Jul 16, 14:20 UTCJul 16, 16:35 UTC2h 15m
2026-07-16 ASA1550 ANC → PHX Jul 16, 07:20 UTCJul 16, 12:30 UTC5h 10m
2026-07-16 ASA271 PDX → ANC Jul 16, 01:20 UTCJul 16, 04:35 UTC3h 15m
2026-07-15 ASA742 PHX → PDX Jul 15, 21:55 UTCJul 16, 00:00 UTC2h 5m
2026-07-15 ASA593 SEA → PHX Jul 15, 17:40 UTCJul 15, 20:35 UTC2h 55m
2026-07-15 ASA1314 SJC → SEA Jul 15, 13:39 UTCJul 15, 15:10 UTC1h 31m
2026-07-15 ASA1314 SJC → SEA Jul 15, 13:40 UTCJul 15, 15:15 UTC1h 35m
2026-07-15 ASA1310 SEA → SJC Jul 15, 04:20 UTCJul 15, 06:15 UTC1h 55m
2026-07-14 ASA503 AUS → SEA Jul 14, 21:40 UTCJul 15, 01:25 UTC3h 44m
2026-07-14 ASA422 SEA → AUS Jul 14, 16:40 UTCJul 14, 20:20 UTC3h 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 N459AS page for operator, model, and routing details .

Mode-S A5939C frequently asked

What is Mode-S code A5939C?
A5939C is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N459AS.
Where is Mode-S A5939C registered?
Mode-S code A5939C 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 A5939C broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:30 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A5939C, octal 51311634, decimal 10,851,228.
What flights does A5939C operate?
Mode-S A5939C has broadcast 20 distinct callsigns, including ASA271, ASA18, ASA270, ASA1332, ASA787.