Apparatus

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sensors Mode-S transponder

A15C54

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N187SY · EMBRAER ERJ-170-200 (long wing) · operated by SKYWEST AIRLINES INC

Hex
A15C54
Octal
50256124
Decimal
10,574,932
Country
US
Tail
N187SY
Type
E75L
No current signal · last broadcast Jul 26, 22:35 UTC
Flights observed
660
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:35 UTC

Last known position

Most recent position reported by Mode-S A15C54.

Country allocation

The ICAO 24-bit address A15C54 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
SKW3284 SkyWest Airlines 10 2026-07-24
SKW3400 SkyWest Airlines 8 2026-06-07
SKW3055 SkyWest Airlines 8 2026-07-23
SKW3480 - 7 2026-07-08
SKW3075 SkyWest Airlines 7 2026-07-17
SKW3465 SkyWest Airlines 6 2026-05-30
SKW3424 SkyWest Airlines 6 2026-05-03
SKW3411 SkyWest Airlines 6 2026-06-06
SKW3363 - 6 2026-07-14
SKW3210 SkyWest Airlines 6 2026-07-25
SKW3082 - 6 2026-07-15
SKW3022 SkyWest Airlines 6 2026-07-24
SKW3494 SkyWest Airlines 5 2026-05-06
SKW3483 SkyWest Airlines 5 2026-07-22
SKW3430 SkyWest Airlines 5 2026-05-01
SKW3425 SkyWest Airlines 5 2026-05-26
SKW3360 SkyWest Airlines 5 2026-06-20
SKW3345 SkyWest Airlines 5 2026-06-13
SKW3341 SkyWest Airlines 5 2026-05-26
SKW3289 SkyWest Airlines 5 2026-06-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SKW3081 SMF → SEA Jul 26, 21:35 UTCJul 26, 22:35 UTC1h 0m
2026-07-26 SKW3347 SAN → SFO Jul 26, 19:15 UTCJul 26, 20:20 UTC1h 5m
2026-07-26 SKW3217 PDX → ONT Jul 26, 15:15 UTCJul 26, 17:25 UTC2h 10m
2026-07-26 SKW3319 SFO → SNA Jul 26, 02:35 UTCJul 26, 04:20 UTC1h 45m
2026-07-26 SKW3211 LEX → ORD Jul 26, 00:20 UTCJul 26, 01:25 UTC1h 5m
2026-07-25 SKW3210 ORD → LEX Jul 25, 21:40 UTCJul 25, 23:20 UTC1h 40m
2026-07-25 SKW3121 LAX → SFO Jul 25, 19:25 UTCJul 25, 20:35 UTC1h 10m
2026-07-25 SKW3121 LAX → SFO Jul 25, 19:30 UTCJul 25, 20:28 UTC58m
2026-07-25 SKW3110 LAX → SJC Jul 25, 16:45 UTCJul 25, 17:40 UTC55m
2026-07-25 SKW3018 DFW → LAW Jul 25, 13:55 UTCJul 25, 15:30 UTC1h 35m
2026-07-25 SKW3298 LAX → SEA Jul 25, 02:30 UTCJul 25, 04:05 UTC1h 35m
2026-07-25 SKW3433 SFO → LAX Jul 25, 00:40 UTCJul 25, 01:00 UTC20m
2026-07-24 SKW3433 SFO → LAX Jul 24, 23:15 UTCJul 24, 23:40 UTC25m
2026-07-24 SKW3087 SNA → SFO Jul 24, 20:45 UTCJul 24, 21:45 UTC1h 0m
2026-07-24 SKW3088 SFO → SNA Jul 24, 18:35 UTCJul 24, 19:55 UTC1h 20m
2026-07-24 SKW3284 LAX → PDX Jul 24, 15:05 UTCJul 24, 17:20 UTC2h 15m
2026-07-24 SKW3284 LAX → PDX Jul 24, 15:03 UTCJul 24, 17:19 UTC2h 16m
2026-07-24 SKW3022 ORD → BNA Jul 24, 00:45 UTCJul 24, 02:50 UTC2h 5m
2026-07-24 SKW3022 ORD → BNA Jul 24, 00:52 UTCJul 24, 02:58 UTC2h 6m
2026-07-23 SKW3041 STS → BUR Jul 23, 23:10 UTCJul 23, 23:30 UTC20m
2026-07-23 SKW3042 EUG → SEA Jul 23, 21:40 UTCJul 23, 22:10 UTC30m
2026-07-23 SKW3042 EUG → SEA Jul 23, 21:46 UTCJul 23, 22:05 UTC19m
2026-07-23 SKW3045 ORD → HPN Jul 23, 19:15 UTCJul 23, 20:10 UTC55m
2026-07-23 SKW3045 ORD → HPN Jul 23, 19:05 UTCJul 23, 20:20 UTC1h 15m
2026-07-23 SKW3055 LAX → LAS Jul 23, 16:35 UTCJul 23, 18:10 UTC1h 35m
2026-07-23 SKW3417 LAX → SFO Jul 23, 14:20 UTCJul 23, 15:30 UTC1h 10m
2026-07-23 SKW3432 SAN → SFO Jul 23, 02:20 UTCJul 23, 03:30 UTC1h 10m
2026-07-23 SKW3231 SNA → SFO Jul 23, 00:10 UTCJul 23, 01:20 UTC1h 10m
2026-07-22 SKW3483 PDX → SJC Jul 22, 21:45 UTCJul 22, 23:00 UTC1h 15m
2026-07-22 SKW3483 PDX → SJC Jul 22, 21:46 UTCJul 22, 22:59 UTC1h 13m
2026-07-22 SKW3117 SAN → SLC Jul 22, 19:05 UTCJul 22, 20:35 UTC1h 30m
2026-07-22 SKW3122 PHX → STS Jul 22, 16:15 UTCJul 22, 17:45 UTC1h 30m
2026-07-22 SKW9797 AUS → SJC Jul 22, 04:10 UTCJul 22, 05:25 UTC1h 15m
2026-07-21 SKW3353 RDM → SFO Jul 21, 14:50 UTCJul 21, 15:55 UTC1h 5m
2026-07-21 SKW3109 LAX → SFO Jul 21, 12:45 UTCJul 21, 13:20 UTC35m
2026-07-21 SKW3303 AUS → LAX Jul 21, 03:15 UTCJul 21, 05:00 UTC1h 45m
2026-07-20 SKW3437 SMF → SAN Jul 20, 19:05 UTCJul 20, 23:55 UTC4h 49m
2026-07-20 SKW3324 SNA → SFO Jul 20, 15:25 UTCJul 20, 17:25 UTC2h 0m
2026-07-20 SKW3323 LAX → PDX Jul 20, 02:50 UTCJul 20, 04:25 UTC1h 35m
2026-07-19 SKW3399 SEA → SFO Jul 19, 22:39 UTCJul 20, 00:36 UTC1h 57m
2026-07-19 SKW3398 PDX → SBP Jul 19, 18:45 UTCJul 19, 20:15 UTC1h 30m
2026-07-19 SKW3398 PDX → SBP Jul 19, 18:54 UTCJul 19, 21:10 UTC2h 16m
2026-07-19 SKW3324 EUG → LAX Jul 19, 15:30 UTCJul 19, 17:25 UTC1h 55m
2026-07-19 SKW3319 - Jul 19, 02:30 UTCJul 19, 04:20 UTC1h 50m
2026-07-19 SKW3211 LEX → ORD Jul 19, 00:25 UTCJul 19, 01:35 UTC1h 10m
2026-07-18 SKW3210 ORD → LEX Jul 18, 21:45 UTCJul 18, 23:25 UTC1h 40m
2026-07-18 SKW3210 ORD → LEX Jul 18, 21:46 UTCJul 18, 23:12 UTC1h 26m
2026-07-18 SKW3045 - Jul 18, 19:25 UTCJul 18, 20:35 UTC1h 10m
2026-07-18 SKW3055 PDX → OAK Jul 18, 17:10 UTCJul 18, 18:40 UTC1h 30m
2026-07-18 SKW3004 SJC → PHX Jul 18, 14:40 UTCJul 18, 16:20 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 N187SY page for operator, model, and routing details .

Mode-S A15C54 frequently asked

What is Mode-S code A15C54?
A15C54 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N187SY.
Where is Mode-S A15C54 registered?
Mode-S code A15C54 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 A15C54 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:35 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A15C54, octal 50256124, decimal 10,574,932.
What flights does A15C54 operate?
Mode-S A15C54 has broadcast 20 distinct callsigns, including SKW3284, SKW3400, SKW3055, SKW3480, SKW3075.