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sensors Mode-S transponder

AC685D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N899SK · BOMBARDIER Regional Jet CRJ-900 · operated by SKYWEST AIRLINES INC

Hex
AC685D
Octal
53064135
Decimal
11,298,909
Country
US
Tail
N899SK
Type
CRJ9
Broadcasting now · callsign SKW4154 · 18,450 ft
Flights observed
14
Distinct callsigns
9
Country
US
Last broadcast
1h ago

Current position

AC685D is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address AC685D 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 9 distinct

Callsign Airline Flights Last seen
SKW3928 SkyWest Airlines 3 2026-05-29
SKW4609 SkyWest Airlines 2 2026-05-26
SKW4003 SkyWest Airlines 2 2026-05-23
SKW3888 SkyWest Airlines 2 2026-05-29
SKW4610 SkyWest Airlines 1 2026-05-22
SKW4154 SkyWest Airlines 1 2026-05-25
SKW4140 SkyWest Airlines 1 2026-05-23
SKW4080 SkyWest Airlines 1 2026-05-29
SKW3829 SkyWest Airlines 1 2026-05-29

Recent flights last 14

DateFlightRouteTakeoffLandingDuration
2026-05-29 SKW3829 DTW → CLE May 29, 23:55 UTCMay 30, 01:15 UTC1h 20m
2026-05-29 SKW4080 DTW → MDW May 29, 20:40 UTCMay 29, 22:20 UTC1h 40m
2026-05-29 SKW3928 JFK → PIT May 29, 17:50 UTCMay 29, 18:45 UTC55m
2026-05-29 SKW3928 JFK → PIT May 29, 17:49 UTCMay 29, 18:44 UTC55m
2026-05-29 SKW3928 JFK → PIT May 29, 15:50 UTCMay 29, 16:50 UTC1h 0m
2026-05-29 SKW3888 MSN → MSP May 29, 13:45 UTCMay 29, 14:35 UTC50m
2026-05-29 SKW3888 MSN → MSP May 29, 13:39 UTCMay 29, 14:34 UTC55m
2026-05-26 SKW4609 MSN → YYZ May 26, 18:51 UTCMay 26, 19:58 UTC1h 7m
2026-05-26 SKW4609 MSN → YYZ May 26, 18:34 UTCMay 26, 20:00 UTC1h 25m
2026-05-25 SKW4154 MSP → CMH May 25, 03:30 UTCMay 25, 04:30 UTC1h 0m
2026-05-23 SKW4140 DTW → YYZ May 23, 22:20 UTCMay 23, 23:05 UTC45m
2026-05-23 SKW4003 DTW → BTV May 23, 02:05 UTCMay 23, 02:45 UTC39m
2026-05-23 SKW4003 DTW → BTV May 23, 02:08 UTCMay 23, 02:41 UTC33m
2026-05-22 SKW4610 SJC → SLC May 22, 20:55 UTCMay 22, 23:25 UTC2h 30m

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 N899SK page for operator, model, and routing details .

Mode-S AC685D frequently asked

What is Mode-S code AC685D?
AC685D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N899SK.
Where is Mode-S AC685D registered?
Mode-S code AC685D 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 AC685D broadcasting right now?
Yes. Mode-S AC685D is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC685D, octal 53064135, decimal 11,298,909.
What flights does AC685D operate?
Mode-S AC685D has broadcast 9 distinct callsigns, including SKW3928, SKW4609, SKW4003, SKW3888, SKW4610.