Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A25CDC

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N251SY · EMBRAER ERJ-170-200 (long wing) · operated by SKYWEST AIRLINES INC

Hex
A25CDC
Octal
50456334
Decimal
10,640,604
Country
US
Tail
N251SY
Type
E75L
Broadcasting now · callsign SKW3790 · 22,000 ft
Flights observed
655
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:35 UTC

Current position

A25CDC is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A25CDC 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
SKW4062 - 9 2026-07-11
SKW3991 - 9 2026-07-14
SKW3937 - 9 2026-07-01
SKW3903 - 9 2026-07-05
SKW3825 - 9 2026-07-05
SKW4141 - 8 2026-07-12
SKW4006 - 8 2026-07-05
SKW3880 - 8 2026-07-05
SKW3830 SkyWest Airlines 8 2026-07-26
SKW4134 - 7 2026-07-03
SKW4042 SkyWest Airlines 7 2026-06-02
SKW3999 - 7 2026-07-11
SKW3896 SkyWest Airlines 7 2026-07-20
SKW3876 SkyWest Airlines 7 2026-05-04
SKW3765 SkyWest Airlines 7 2026-07-02
SKW3732 SkyWest Airlines 7 2026-06-01
SKW3681 - 7 2026-07-02
SKW4031 - 6 2026-07-16
SKW3841 - 6 2026-07-21
SKW3789 - 6 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SKW3892 ICT → MSP Jul 26, 21:20 UTCJul 26, 22:35 UTC1h 15m
2026-07-26 SKW3892 ICT → MSP Jul 26, 19:10 UTCJul 26, 20:15 UTC1h 5m
2026-07-26 SKW4444 SLC → GEG Jul 26, 16:50 UTCJul 26, 18:10 UTC1h 20m
2026-07-26 SKW3830 OAK → LAX Jul 26, 14:36 UTCJul 26, 15:01 UTC25m
2026-07-26 SKW3830 OAK → LAX Jul 26, 14:25 UTCJul 26, 15:00 UTC35m
2026-07-26 SKW4100 MDW → DTW Jul 26, 04:15 UTCJul 26, 05:50 UTC1h 35m
2026-07-26 SKW4100 MDW → DTW Jul 26, 01:15 UTCJul 26, 03:15 UTC2h 0m
2026-07-25 SKW3891 LAX → OAK Jul 25, 23:10 UTCJul 25, 23:55 UTC45m
2026-07-25 SKW3891 LAX → OAK Jul 25, 21:50 UTCJul 25, 22:20 UTC30m
2026-07-25 SKW3881 DTW → PVD Jul 25, 18:45 UTCJul 25, 20:05 UTC1h 20m
2026-07-25 SKW3755 LAX → SMF Jul 25, 16:25 UTCJul 25, 17:25 UTC1h 0m
2026-07-25 SKW3725 SBN → ATL Jul 25, 13:15 UTCJul 25, 15:10 UTC1h 55m
2026-07-25 SKW3692 SLC → OAK Jul 25, 02:55 UTCJul 25, 03:55 UTC1h 0m
2026-07-25 SKW4124 EUG → SEA Jul 25, 00:52 UTCJul 25, 01:21 UTC29m
2026-07-25 SKW4124 EUG → SEA Jul 25, 00:45 UTCJul 25, 01:30 UTC45m
2026-07-24 SKW181H ORD → BOS Jul 24, 23:05 UTCJul 24, 23:55 UTC50m
2026-07-24 SKW3966 AUS → CVG Jul 24, 18:30 UTCJul 24, 20:45 UTC2h 15m
2026-07-24 SKW3966 AUS → CVG Jul 24, 14:55 UTCJul 24, 17:30 UTC2h 35m
2026-07-24 SKW4008 DTW → MKE Jul 24, 12:45 UTCJul 24, 13:20 UTC35m
2026-07-24 SKW3913 MQT → DTW Jul 24, 05:10 UTCJul 24, 05:35 UTC25m
2026-07-24 SKW3688 DTW → CMH Jul 24, 02:45 UTCJul 24, 03:55 UTC1h 10m
2026-07-24 SKW3688 DTW → CMH Jul 24, 00:15 UTCJul 24, 01:25 UTC1h 10m
2026-07-23 SKW3679 - Jul 23, 19:10 UTCJul 23, 22:10 UTC3h 0m
2026-07-23 SKW138Y LAX → TUS Jul 23, 16:45 UTCJul 23, 17:55 UTC1h 10m
2026-07-23 SKW4115 ABQ → LAX Jul 23, 12:20 UTCJul 23, 13:55 UTC1h 35m
2026-07-23 SKW4098 MDW → MSP Jul 23, 04:00 UTCJul 23, 05:35 UTC1h 35m
2026-07-23 SKW4091 ABQ → LAX Jul 23, 00:55 UTCJul 23, 02:30 UTC1h 35m
2026-07-22 SKW4091 ABQ → LAX Jul 22, 22:15 UTCJul 22, 23:55 UTC1h 40m
2026-07-22 SKW3744 LAX → OAK Jul 22, 19:50 UTCJul 22, 21:00 UTC1h 10m
2026-07-22 SKW3680 IAD → MSP Jul 22, 15:45 UTCJul 22, 18:30 UTC2h 45m
2026-07-22 SKW4036 HPN → ATL Jul 22, 13:20 UTCJul 22, 14:00 UTC40m
2026-07-22 SKW4036 HPN → ATL Jul 22, 13:28 UTCJul 22, 13:59 UTC31m
2026-07-22 SKW4009 SEA → SFO Jul 22, 02:00 UTCJul 22, 04:05 UTC2h 5m
2026-07-21 SKW3585 JFK → ORD Jul 21, 22:30 UTCJul 22, 00:20 UTC1h 50m
2026-07-21 SKW3585 JFK → ORD Jul 21, 22:31 UTCJul 22, 00:08 UTC1h 37m
2026-07-21 SKW3841 SBA → SLC Jul 21, 19:45 UTCJul 21, 21:20 UTC1h 35m
2026-07-21 SKW3841 SLC → SBA Jul 21, 17:00 UTCJul 21, 18:40 UTC1h 40m
2026-07-21 SKW3745 - Jul 21, 14:25 UTCJul 21, 16:00 UTC1h 35m
2026-07-21 SKW3745 TUS → SLC Jul 21, 14:17 UTCJul 21, 15:48 UTC1h 31m
2026-07-21 SKW4054 SLC → OAK Jul 21, 02:45 UTCJul 21, 04:20 UTC1h 35m
2026-07-20 SKW3896 OMA → SLC Jul 20, 23:05 UTCJul 21, 01:20 UTC2h 14m
2026-07-20 SKW3896 OMA → SLC Jul 20, 19:35 UTCJul 20, 21:30 UTC1h 55m
2026-07-20 SKW4029 SJC → SLC Jul 20, 13:35 UTCJul 20, 15:35 UTC2h 0m
2026-07-20 SKW3703 SLC → OKC Jul 20, 02:40 UTCJul 20, 04:40 UTC2h 0m
2026-07-19 SKW3801 JFK → IAD Jul 19, 20:55 UTCJul 19, 22:15 UTC1h 20m
2026-07-19 SKW3779 SEA → MFR Jul 19, 18:55 UTCJul 19, 20:05 UTC1h 10m
2026-07-19 SKW4092 - Jul 19, 14:55 UTCJul 19, 16:05 UTC1h 10m
2026-07-19 SKW4039 - Jul 19, 03:15 UTCJul 19, 04:10 UTC55m
2026-07-19 SKW4039 SEA → BZN Jul 19, 03:08 UTCJul 19, 04:30 UTC1h 22m
2026-07-19 SKW4124 EUG → SEA Jul 19, 01:00 UTCJul 19, 01:45 UTC45m

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 N251SY page for operator, model, and routing details .

Mode-S A25CDC frequently asked

What is Mode-S code A25CDC?
A25CDC is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N251SY.
Where is Mode-S A25CDC registered?
Mode-S code A25CDC 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 A25CDC broadcasting right now?
Yes. Mode-S A25CDC is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A25CDC, octal 50456334, decimal 10,640,604.
What flights does A25CDC operate?
Mode-S A25CDC has broadcast 20 distinct callsigns, including SKW4062, SKW3991, SKW3937, SKW3903, SKW3825.