Apparatus

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sensors Mode-S transponder

A9B273

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N724AL · operated by ALASKA AIRLINES INC

Hex
A9B273
Octal
52331163
Decimal
11,121,267
Country
US
Tail
N724AL
Type
B39M
No current signal · last broadcast 5h ago
Flights observed
373
Distinct callsigns
20
Country
US
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S A9B273.

Country allocation

The ICAO 24-bit address A9B273 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
ASA379 - 6 2026-06-27
ASA378 - 5 2026-06-27
ASA228 Alaska Airlines 5 2026-06-03
ASA200 Alaska Airlines 5 2026-06-12
ASA752 - 4 2026-06-15
ASA670 Alaska Airlines 4 2026-05-12
ASA647 - 4 2026-07-13
ASA639 Alaska Airlines 4 2026-04-15
ASA565 Alaska Airlines 4 2026-06-08
ASA550 - 4 2026-06-27
ASA519 - 4 2026-06-28
ASA465 Alaska Airlines 4 2026-06-05
ASA419 Alaska Airlines 4 2026-04-17
ASA331 Alaska Airlines 4 2026-06-01
ASA300 Alaska Airlines 4 2026-04-16
ASA94 Alaska Airlines 3 2026-05-11
ASA799 - 3 2026-04-14
ASA745 Alaska Airlines 3 2026-05-24
ASA677 Alaska Airlines 3 2026-05-12
ASA657 Alaska Airlines 3 2026-05-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 ASA416 SEA → BNA Jul 14, 00:55 UTCJul 14, 04:55 UTC4h 0m
2026-07-13 ASA418 - Jul 13, 19:30 UTCJul 13, 22:40 UTC3h 10m
2026-07-13 ASA418 - Jul 13, 15:10 UTCJul 13, 18:10 UTC3h 0m
2026-07-13 ASA647 STL → SEA Jul 13, 00:55 UTCJul 13, 04:40 UTC3h 45m
2026-07-13 ASA647 STL → SEA Jul 13, 00:55 UTCJul 13, 04:28 UTC3h 33m
2026-07-12 ASA647 SEA → STL Jul 12, 20:20 UTCJul 12, 23:40 UTC3h 20m
2026-07-12 ASA1327 SFO → SEA Jul 12, 17:10 UTCJul 12, 18:45 UTC1h 35m
2026-07-12 ASA1327 SFO → SEA Jul 12, 17:10 UTCJul 12, 18:34 UTC1h 24m
2026-07-11 ASA1561 ANC → SFO Jul 11, 23:25 UTCJul 12, 03:40 UTC4h 15m
2026-07-11 ASA1825 PWK → ANC Jul 11, 15:30 UTCJul 11, 21:20 UTC5h 50m
2026-07-11 ASA1543 ANC → ORD Jul 11, 07:20 UTCJul 11, 13:05 UTC5h 45m
2026-07-10 ASA53 - Jul 10, 17:25 UTCJul 10, 22:10 UTC4h 45m
2026-07-09 ASA1351 - Jul 9, 23:55 UTCJul 10, 12:50 UTC12h 55m
2026-07-09 ASA502 SEA → LAX Jul 9, 20:00 UTCJul 9, 22:10 UTC2h 10m
2026-07-09 ASA9443 SAT → SEA Jul 9, 14:21 UTCJul 9, 17:44 UTC3h 23m
2026-07-09 ASA9443 - Jul 9, 14:05 UTCJul 9, 18:00 UTC3h 55m
2026-07-01 ASA9421 - Jul 1, 16:15 UTCJul 1, 19:55 UTC3h 40m
2026-06-30 ASA517 PPM → SEA Jun 30, 23:00 UTCJul 1, 04:40 UTC5h 40m
2026-06-30 ASA516 SEA → FLL Jun 30, 15:55 UTCJun 30, 21:20 UTC5h 25m
2026-06-30 ASA683 SMF → SEA Jun 30, 00:14 UTCJun 30, 01:50 UTC1h 36m
2026-06-30 ASA683 SMF → SEA Jun 30, 00:14 UTCJun 30, 01:43 UTC1h 29m
2026-06-29 ASA681 SEA → SMF Jun 29, 21:39 UTCJun 29, 22:59 UTC1h 20m
2026-06-29 ASA1477 - Jun 29, 17:24 UTCJun 29, 20:00 UTC2h 35m
2026-06-29 ASA1361 SEA → SAN Jun 29, 13:30 UTCJun 29, 15:49 UTC2h 20m
2026-06-29 ASA599 - Jun 29, 03:29 UTCJun 29, 04:55 UTC1h 25m
2026-06-29 ASA598 SFO → ORD Jun 29, 00:49 UTCJun 29, 02:05 UTC1h 15m
2026-06-29 ASA598 SFO → ORD Jun 29, 00:49 UTCJun 29, 01:59 UTC1h 10m
2026-06-28 ASA384 - Jun 28, 21:04 UTCJun 28, 22:55 UTC1h 50m
2026-06-28 ASA383 - Jun 28, 18:00 UTCJun 28, 19:25 UTC1h 25m
2026-06-28 ASA519 - Jun 28, 16:05 UTCJun 28, 16:09 UTC5m
2026-06-28 ASA519 - Jun 28, 12:25 UTCJun 28, 16:09 UTC3h 45m
2026-06-28 ASA519 SAT → SEA Jun 28, 12:21 UTCJun 28, 15:48 UTC3h 27m
2026-06-28 ASA520 - Jun 28, 06:20 UTCJun 28, 09:55 UTC3h 35m
2026-06-27 ASA379 - Jun 27, 22:45 UTCJun 28, 04:05 UTC5h 20m
2026-06-27 ASA378 SEA → BWI Jun 27, 16:30 UTCJun 27, 21:04 UTC4h 35m
2026-06-27 ASA550 DFW → SEA Jun 27, 02:50 UTCJun 27, 06:19 UTC3h 30m
2026-06-26 ASA380 SEA → MSP Jun 26, 22:05 UTCJun 27, 00:29 UTC2h 25m
2026-06-26 ASA1394 PDX → SAN Jun 26, 18:34 UTCJun 26, 20:34 UTC2h 0m
2026-06-26 ASA679 SJC → PDX Jun 26, 15:15 UTCJun 26, 16:54 UTC1h 40m
2026-06-26 ASA1310 SEA → SJC Jun 26, 04:20 UTCJun 26, 06:04 UTC1h 45m
2026-06-26 ASA1310 SEA → SJC Jun 26, 04:22 UTCJun 26, 05:57 UTC1h 35m
2026-06-25 ASA494 - Jun 25, 22:39 UTCJun 26, 02:44 UTC4h 5m
2026-06-25 ASA494 - Jun 25, 17:49 UTCJun 25, 21:20 UTC3h 30m
2026-06-25 ASA625 - Jun 25, 11:35 UTCJun 25, 15:59 UTC4h 25m
2026-06-25 ASA625 IND → SEA Jun 25, 11:26 UTCJun 25, 15:54 UTC4h 28m
2026-06-25 ASA624 SEA → IND Jun 25, 06:09 UTCJun 25, 09:25 UTC3h 15m
2026-06-24 ASA379 - Jun 24, 22:19 UTCJun 25, 03:44 UTC5h 25m
2026-06-24 ASA378 SEA → BWI Jun 24, 16:19 UTCJun 24, 20:40 UTC4h 20m
2026-06-24 ASA1444 SLC → SEA Jun 24, 12:44 UTCJun 24, 14:24 UTC1h 40m
2026-06-24 ASA373 SEA → SLC Jun 24, 00:05 UTCJun 24, 01:44 UTC1h 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 N724AL page for operator, model, and routing details .

Mode-S A9B273 frequently asked

What is Mode-S code A9B273?
A9B273 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N724AL.
Where is Mode-S A9B273 registered?
Mode-S code A9B273 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 A9B273 broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A9B273, octal 52331163, decimal 11,121,267.
What flights does A9B273 operate?
Mode-S A9B273 has broadcast 20 distinct callsigns, including ASA379, ASA378, ASA228, ASA200, ASA752.