Apparatus

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sensors Mode-S transponder

A506D5

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N423AS · BOEING 737-900 · operated by ALASKA AIRLINES INC

Hex
A506D5
Octal
51203325
Decimal
10,815,189
Country
US
Tail
N423AS
Type
B739
No current signal · last broadcast 2h ago
Flights observed
407
Distinct callsigns
20
Country
US
Last broadcast
2h ago

Last known position

Most recent position reported by Mode-S A506D5.

Country allocation

The ICAO 24-bit address A506D5 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
ASA326 - 7 2026-06-22
ASA420 - 6 2026-07-01
ASA787 Alaska Airlines 5 2026-04-13
ASA307 - 5 2026-07-13
ASA695 Alaska Airlines 4 2026-06-16
ASA685 Alaska Airlines 4 2026-05-03
ASA549 Alaska Airlines 4 2026-05-20
ASA531 - 4 2026-07-01
ASA450 - 4 2026-07-03
ASA438 Alaska Airlines 4 2026-05-02
ASA338 Alaska Airlines 4 2026-05-03
ASA334 - 4 2026-06-19
ASA284 Alaska Airlines 4 2026-05-23
ASA212 - 4 2026-07-07
ASA1315 - 4 2026-06-16
ASA124 Alaska Airlines 4 2026-04-15
ASA105 Alaska Airlines 4 2026-04-18
ASA95 Alaska Airlines 3 2026-05-28
ASA90 Alaska Airlines 3 2026-06-24
ASA798 - 3 2026-06-28

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 ASA304 BOS → SEA Jul 13, 23:00 UTCJul 14, 04:25 UTC5h 25m
2026-07-13 ASA306 SEA → BOS Jul 13, 16:33 UTCJul 13, 21:01 UTC4h 28m
2026-07-13 ASA306 SEA → BOS Jul 13, 16:25 UTCJul 13, 21:15 UTC4h 50m
2026-07-13 ASA440 - Jul 13, 11:10 UTCJul 13, 14:45 UTC3h 35m
2026-07-13 ASA307 SEA → MKE Jul 13, 01:25 UTCJul 13, 04:45 UTC3h 20m
2026-07-13 ASA307 SEA → MKE Jul 13, 01:24 UTCJul 13, 04:37 UTC3h 13m
2026-07-12 ASA363 ANC → SEA Jul 12, 20:20 UTCJul 12, 23:35 UTC3h 15m
2026-07-12 ASA432 DEN → ANC Jul 12, 13:40 UTCJul 12, 18:35 UTC4h 55m
2026-07-12 ASA1627 PDX → DEN Jul 12, 03:10 UTCJul 12, 05:15 UTC2h 5m
2026-07-11 ASA1423 - Jul 11, 22:50 UTCJul 12, 01:20 UTC2h 30m
2026-07-11 ASA1422 PDX → SJD Jul 11, 17:20 UTCJul 11, 20:49 UTC3h 29m
2026-07-11 ASA1422 - Jul 11, 17:10 UTCJul 11, 20:05 UTC2h 55m
2026-07-11 ASA609 ANC → PDX Jul 11, 10:25 UTCJul 11, 13:35 UTC3h 10m
2026-07-10 ASA1347 FAI → ANC Jul 10, 23:00 UTCJul 10, 23:45 UTC45m
2026-07-10 ASA1336 ANC → FAI Jul 10, 21:15 UTCJul 10, 22:00 UTC45m
2026-07-10 ASA1532 PHX → ANC Jul 10, 02:05 UTCJul 10, 07:15 UTC5h 10m
2026-07-10 ASA1532 PHX → ANC Jul 10, 02:01 UTCJul 10, 07:14 UTC5h 13m
2026-07-09 ASA731 PDX → PHX Jul 9, 22:20 UTCJul 10, 00:35 UTC2h 15m
2026-07-09 ASA1567 ANC → PDX Jul 9, 17:35 UTCJul 9, 20:50 UTC3h 15m
2026-07-09 ASA85 SEA → ANC Jul 9, 13:15 UTCJul 9, 16:25 UTC3h 10m
2026-07-09 ASA85 SEA → ANC Jul 9, 13:15 UTCJul 9, 16:24 UTC3h 9m
2026-07-09 ASA591 CUN → SFO Jul 9, 03:50 UTCJul 9, 05:25 UTC1h 35m
2026-07-09 ASA504 OAK → SEA Jul 9, 01:00 UTCJul 9, 02:25 UTC1h 25m
2026-07-09 ASA504 OAK → SEA Jul 9, 00:56 UTCJul 9, 02:13 UTC1h 17m
2026-07-08 ASA1383 BUR → PDX Jul 8, 21:20 UTCJul 8, 23:05 UTC1h 45m
2026-07-08 ASA1384 PDX → BUR Jul 8, 18:30 UTCJul 8, 20:10 UTC1h 40m
2026-07-08 ASA1384 PDX → BUR Jul 8, 18:20 UTCJul 8, 20:15 UTC1h 55m
2026-07-08 ASA511 BNA → PDX Jul 8, 14:10 UTCJul 8, 16:35 UTC2h 25m
2026-07-08 ASA1550 - Jul 8, 07:30 UTCJul 8, 12:20 UTC4h 50m
2026-07-07 ASA212 SFO → ANC Jul 7, 04:00 UTCJul 7, 08:05 UTC4h 5m
2026-07-07 ASA212 SFO → ANC Jul 7, 03:58 UTCJul 7, 08:01 UTC4h 3m
2026-07-07 ASA1385 SEA → SFO Jul 7, 01:00 UTCJul 7, 02:45 UTC1h 45m
2026-07-06 ASA1305 - Jul 6, 21:10 UTCJul 6, 23:10 UTC2h 0m
2026-07-06 ASA1602 SFO → LAX Jul 6, 18:40 UTCJul 6, 19:50 UTC1h 10m
2026-07-06 ASA526 PDX → SFO Jul 6, 15:55 UTCJul 6, 17:25 UTC1h 30m
2026-07-06 ASA526 PDX → SFO Jul 6, 15:54 UTCJul 6, 17:15 UTC1h 21m
2026-07-05 ASA1396 AUS → PDX Jul 5, 22:55 UTCJul 6, 02:35 UTC3h 40m
2026-07-05 ASA1396 AUS → PDX Jul 5, 22:52 UTCJul 6, 02:30 UTC3h 38m
2026-07-05 ASA540 PDX → AUS Jul 5, 17:50 UTCJul 5, 21:15 UTC3h 25m
2026-07-05 ASA1629 LAS → PDX Jul 5, 14:15 UTCJul 5, 16:00 UTC1h 45m
2026-07-05 ASA478 SEA → LAS Jul 5, 01:30 UTCJul 5, 03:30 UTC2h 0m
2026-07-04 ASA567 - Jul 4, 21:10 UTCJul 4, 23:15 UTC2h 5m
2026-07-04 ASA565 SEA → ONT Jul 4, 17:45 UTCJul 4, 19:50 UTC2h 5m
2026-07-04 ASA625 - Jul 4, 11:15 UTCJul 4, 15:35 UTC4h 20m
2026-07-04 ASA624 SEA → IND Jul 4, 05:45 UTCJul 4, 09:25 UTC3h 40m
2026-07-03 ASA450 - Jul 3, 22:35 UTCJul 4, 03:15 UTC4h 40m
2026-07-03 ASA450 SEA → CMH Jul 3, 17:10 UTCJul 3, 21:20 UTC4h 10m
2026-07-03 ASA302 SJC → LIH Jul 3, 11:10 UTCJul 3, 15:30 UTC4h 20m
2026-07-03 ASA298 SEA → CVG Jul 3, 05:25 UTCJul 3, 09:30 UTC4h 5m
2026-07-02 ASA572 RDU → SEA Jul 2, 22:00 UTCJul 3, 03:00 UTC5h 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 N423AS page for operator, model, and routing details .

Mode-S A506D5 frequently asked

What is Mode-S code A506D5?
A506D5 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N423AS.
Where is Mode-S A506D5 registered?
Mode-S code A506D5 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 A506D5 broadcasting right now?
No active broadcast right now. Last signal was 2h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A506D5, octal 51203325, decimal 10,815,189.
What flights does A506D5 operate?
Mode-S A506D5 has broadcast 20 distinct callsigns, including ASA326, ASA420, ASA787, ASA307, ASA695.