Apparatus

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sensors Mode-S transponder

AB8173

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N840SK · BOMBARDIER Regional Jet CRJ-900 · operated by DELTA AIR LINES INC

Hex
AB8173
Octal
52700563
Decimal
11,239,795
Country
US
Tail
N840SK
Type
CRJ9
No current signal · last broadcast 1h ago
Flights observed
745
Distinct callsigns
20
Country
US
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S AB8173.

Country allocation

The ICAO 24-bit address AB8173 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
SKW4034 - 29 2026-07-08
SKW4021 - 17 2026-06-29
SKW4059 - 15 2026-06-30
SKW3752 - 15 2026-07-13
SKW3949 - 13 2026-07-13
SKW3898 - 13 2026-07-07
SKW3878 SkyWest Airlines 13 2026-05-29
SKW4166 - 12 2026-07-12
SKW3889 - 12 2026-06-28
SKW3784 SkyWest Airlines 12 2026-05-20
SKW3565 SkyWest Airlines 12 2026-06-23
SKW4173 - 11 2026-07-14
SKW3993 SkyWest Airlines 11 2026-06-03
SKW3919 - 11 2026-07-11
SKW3826 - 11 2026-07-01
SKW3500 - 11 2026-07-09
SKW3980 - 10 2026-06-22
SKW3738 SkyWest Airlines 10 2026-06-03
SKW4110 - 9 2026-07-06
SKW3962 - 9 2026-07-12

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 SKW4173 - Jul 14, 01:55 UTCJul 14, 02:20 UTC25m
2026-07-13 SKW4007 - Jul 13, 22:50 UTCJul 14, 00:20 UTC1h 30m
2026-07-13 SKW4007 - Jul 13, 20:25 UTCJul 13, 21:45 UTC1h 20m
2026-07-13 SKW3752 - Jul 13, 18:40 UTCJul 13, 19:10 UTC30m
2026-07-13 SKW3752 - Jul 13, 16:50 UTCJul 13, 17:05 UTC15m
2026-07-13 SKW3671 - Jul 13, 14:40 UTCJul 13, 15:35 UTC55m
2026-07-13 SKW3671 - Jul 13, 12:45 UTCJul 13, 13:35 UTC50m
2026-07-13 SKW3858 - Jul 13, 10:30 UTCJul 13, 10:45 UTC15m
2026-07-13 SKW3858 ELM → DTW Jul 13, 10:26 UTCJul 13, 11:13 UTC47m
2026-07-13 SKW3949 - Jul 13, 02:05 UTCJul 13, 02:50 UTC45m
2026-07-12 SKW4166 - Jul 12, 23:50 UTCJul 13, 00:35 UTC45m
2026-07-12 SKW4166 ATW → DTW Jul 12, 23:58 UTCJul 13, 00:35 UTC37m
2026-07-12 SKW4166 - Jul 12, 21:40 UTCJul 12, 22:30 UTC50m
2026-07-12 SKW3941 - Jul 12, 19:55 UTCJul 12, 20:25 UTC30m
2026-07-12 SKW3941 - Jul 12, 18:20 UTCJul 12, 18:45 UTC25m
2026-07-12 SKW3685 - Jul 12, 15:25 UTCJul 12, 16:55 UTC1h 30m
2026-07-12 SKW3685 - Jul 12, 13:01 UTCJul 12, 14:30 UTC1h 30m
2026-07-12 SKW3962 - Jul 12, 10:55 UTCJul 12, 11:20 UTC25m
2026-07-12 SKW4173 - Jul 12, 01:50 UTCJul 12, 02:10 UTC20m
2026-07-11 SKW3919 - Jul 11, 22:20 UTCJul 11, 22:45 UTC25m
2026-07-11 SKW3919 - Jul 11, 20:30 UTCJul 11, 20:55 UTC25m
2026-07-11 SKW3752 - Jul 11, 18:30 UTCJul 11, 18:45 UTC15m
2026-07-11 SKW3752 FWA → DTW Jul 11, 18:38 UTCJul 11, 18:50 UTC12m
2026-07-11 SKW3752 - Jul 11, 16:45 UTCJul 11, 17:10 UTC25m
2026-07-11 SKW3821 - Jul 11, 14:40 UTCJul 11, 15:30 UTC50m
2026-07-11 SKW3821 SDF → DTW Jul 11, 14:48 UTCJul 11, 15:23 UTC35m
2026-07-11 SKW3821 - Jul 11, 12:35 UTCJul 11, 13:20 UTC45m
2026-07-10 SKW4166 - Jul 10, 23:40 UTCJul 11, 00:25 UTC45m
2026-07-10 SKW4166 - Jul 10, 21:35 UTCJul 10, 22:35 UTC1h 0m
2026-07-10 SKW3752 - Jul 10, 19:50 UTCJul 10, 20:15 UTC25m
2026-07-10 SKW3752 - Jul 10, 18:10 UTCJul 10, 18:30 UTC20m
2026-07-10 SKW3685 - Jul 10, 15:30 UTCJul 10, 17:00 UTC1h 30m
2026-07-10 SKW3685 - Jul 10, 12:45 UTCJul 10, 14:15 UTC1h 30m
2026-07-10 SKW3858 - Jul 10, 10:25 UTCJul 10, 11:15 UTC50m
2026-07-10 SKW3949 - Jul 10, 02:10 UTCJul 10, 02:55 UTC45m
2026-07-10 SKW3949 DTW → ELM Jul 10, 02:09 UTCJul 10, 02:55 UTC46m
2026-07-09 SKW4007 - Jul 9, 23:20 UTCJul 10, 00:45 UTC1h 25m
2026-07-09 SKW4007 - Jul 9, 20:45 UTCJul 9, 22:10 UTC1h 25m
2026-07-09 SKW3559 - Jul 9, 18:30 UTCJul 9, 19:15 UTC45m
2026-07-09 SKW3559 CLE → DTW Jul 9, 18:33 UTCJul 9, 19:13 UTC40m
2026-07-09 SKW3559 - Jul 9, 17:00 UTCJul 9, 17:20 UTC20m
2026-07-09 SKW3500 - Jul 9, 14:35 UTCJul 9, 15:05 UTC30m
2026-07-09 SKW3500 - Jul 9, 13:05 UTCJul 9, 13:30 UTC25m
2026-07-09 SKW3858 - Jul 9, 10:20 UTCJul 9, 11:10 UTC50m
2026-07-09 SKW3949 - Jul 9, 02:10 UTCJul 9, 02:55 UTC45m
2026-07-08 SKW3782 SMF → LAX Jul 8, 22:55 UTCJul 8, 23:30 UTC35m
2026-07-08 SKW3782 SMF → LAX Jul 8, 21:05 UTCJul 8, 21:40 UTC35m
2026-07-08 SKW4034 - Jul 8, 19:10 UTCJul 8, 19:40 UTC30m
2026-07-08 SKW4034 - Jul 8, 17:30 UTCJul 8, 18:00 UTC30m
2026-07-08 SKW167P OAK → LAX Jul 8, 15:25 UTCJul 8, 16:00 UTC35m

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 N840SK page for operator, model, and routing details .

Mode-S AB8173 frequently asked

What is Mode-S code AB8173?
AB8173 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N840SK.
Where is Mode-S AB8173 registered?
Mode-S code AB8173 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 AB8173 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 AB8173, octal 52700563, decimal 11,239,795.
What flights does AB8173 operate?
Mode-S AB8173 has broadcast 20 distinct callsigns, including SKW4034, SKW4021, SKW4059, SKW3752, SKW3949.