Apparatus

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sensors Mode-S transponder

A87428

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N644AS · BOEING 737-700 · operated by ALASKA AIRLINES INC

Hex
A87428
Octal
52072050
Decimal
11,039,784
Country
US
Tail
N644AS
Type
B737
No current signal · last broadcast 1h ago
Flights observed
35
Distinct callsigns
18
Country
US
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S A87428.

Country allocation

The ICAO 24-bit address A87428 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 18 distinct

Callsign Airline Flights Last seen
ASA66 Alaska Airlines 5 2026-04-15
ASA64 Alaska Airlines 4 2026-04-17
ASA174 Alaska Airlines 3 2026-04-15
ASA136 Alaska Airlines 3 2026-04-18
ASA706 Alaska Airlines 2 2026-04-17
ASA705 - 2 2026-04-17
ASA55 - 2 2026-04-16
ASA374 Alaska Airlines 2 2026-04-18
ASA135 Alaska Airlines 2 2026-04-16
ASA1328 Alaska Airlines 2 2026-04-17
ASA601 Alaska Airlines 1 2026-04-17
ASA273 - 1 2026-04-17
ASA192 Alaska Airlines 1 2026-04-14
ASA173 Alaska Airlines 1 2026-04-15
ASA168 - 1 2026-04-14
ASA151 - 1 2026-04-18
ASA132 - 1 2026-04-18
ASA123 Alaska Airlines 1 2026-04-16

Recent flights last 35

DateFlightRouteTakeoffLandingDuration
2026-04-18 ASA132 - Apr 18, 15:55 UTCApr 18, 16:00 UTC5m
2026-04-18 ASA151 ANC → FAI Apr 18, 14:15 UTCApr 18, 15:00 UTC45m
2026-04-18 ASA136 JFK → SEA Apr 18, 07:25 UTCApr 18, 08:20 UTC55m
2026-04-18 ASA136 JFK → SEA Apr 18, 05:25 UTCApr 18, 07:20 UTC1h 55m
2026-04-18 ASA136 JFK → SEA Apr 18, 05:10 UTCApr 18, 08:20 UTC3h 10m
2026-04-18 ASA374 SJD → SJC Apr 18, 03:25 UTCApr 18, 03:50 UTC25m
2026-04-18 ASA374 SJD → SJC Apr 18, 02:10 UTCApr 18, 03:20 UTC1h 10m
2026-04-17 ASA1328 SEA → SFO Apr 17, 23:25 UTCApr 18, 00:25 UTC1h 0m
2026-04-17 ASA1328 SEA → SFO Apr 17, 22:45 UTCApr 18, 00:22 UTC1h 37m
2026-04-17 ASA601 SEA → SFO Apr 17, 19:55 UTCApr 17, 21:20 UTC1h 25m
2026-04-17 ASA273 - Apr 17, 17:30 UTCApr 17, 18:25 UTC55m
2026-04-17 ASA705 - Apr 17, 15:20 UTCApr 17, 16:00 UTC40m
2026-04-17 ASA705 - Apr 17, 14:15 UTCApr 17, 15:15 UTC59m
2026-04-17 ASA706 SFO → LAS Apr 17, 05:20 UTCApr 17, 06:20 UTC1h 0m
2026-04-17 ASA706 SFO → LAS Apr 17, 04:47 UTCApr 17, 06:17 UTC1h 30m
2026-04-17 ASA64 KTN → SEA Apr 17, 02:00 UTCApr 17, 03:15 UTC1h 15m
2026-04-17 ASA64 KTN → SEA Apr 17, 00:10 UTCApr 17, 00:25 UTC15m
2026-04-16 ASA64 KTN → SEA Apr 16, 21:39 UTCApr 16, 21:55 UTC15m
2026-04-16 ASA64 KTN → SEA Apr 16, 19:15 UTCApr 16, 20:20 UTC1h 5m
2026-04-16 ASA55 - Apr 16, 17:15 UTCApr 16, 18:00 UTC45m
2026-04-16 ASA55 - Apr 16, 13:54 UTCApr 16, 14:40 UTC45m
2026-04-16 ASA123 LAX → SEA Apr 16, 02:24 UTCApr 16, 03:04 UTC40m
2026-04-16 ASA135 SEA → ANC Apr 16, 01:10 UTCApr 16, 01:15 UTC5m
2026-04-16 ASA135 SEA → ANC Apr 16, 00:35 UTCApr 16, 01:05 UTC30m
2026-04-15 ASA173 SEA → ANC Apr 15, 22:09 UTCApr 15, 22:57 UTC48m
2026-04-15 ASA174 SEA → FAI Apr 15, 21:05 UTCApr 15, 21:20 UTC15m
2026-04-15 ASA174 SEA → FAI Apr 15, 19:05 UTCApr 15, 21:00 UTC1h 55m
2026-04-15 ASA174 SEA → FAI Apr 15, 17:49 UTCApr 15, 21:16 UTC3h 27m
2026-04-15 ASA66 JNU → SEA Apr 15, 02:55 UTCApr 15, 04:10 UTC1h 15m
2026-04-15 ASA66 JNU → SEA Apr 15, 02:10 UTCApr 15, 02:50 UTC40m
2026-04-15 ASA66 JNU → SEA Apr 15, 00:40 UTCApr 15, 00:50 UTC10m
2026-04-14 ASA66 JNU → SEA Apr 14, 22:30 UTCApr 14, 22:50 UTC20m
2026-04-14 ASA66 JNU → SEA Apr 14, 21:15 UTCApr 14, 21:45 UTC30m
2026-04-14 ASA192 SFO → JFK Apr 14, 18:55 UTCApr 14, 19:40 UTC45m
2026-04-14 ASA168 ANC → FAI Apr 14, 17:00 UTCApr 14, 17:40 UTC40m

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 N644AS page for operator, model, and routing details .

Mode-S A87428 frequently asked

What is Mode-S code A87428?
A87428 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N644AS.
Where is Mode-S A87428 registered?
Mode-S code A87428 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 A87428 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 A87428, octal 52072050, decimal 11,039,784.
What flights does A87428 operate?
Mode-S A87428 has broadcast 18 distinct callsigns, including ASA66, ASA64, ASA174, ASA136, ASA706.