Apparatus

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sensors Mode-S transponder

A19ECF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N203SY · EMBRAER ERJ-170-200 (long wing) · operated by SKYWEST AIRLINES INC

Hex
A19ECF
Octal
50317317
Decimal
10,591,951
Country
US
Tail
N203SY
Type
E75L
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
653
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A19ECF.

Country allocation

The ICAO 24-bit address A19ECF 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
SKW5401 SkyWest Airlines 8 2026-07-25
SKW5540 SkyWest Airlines 7 2026-07-26
SKW5972 - 6 2026-07-16
SKW5937 - 6 2026-06-29
SKW5591 - 6 2026-07-07
SKW4628 SkyWest Airlines 6 2026-07-25
SKW5934 - 5 2026-07-08
SKW5789 - 5 2026-07-17
SKW5672 - 5 2026-07-12
SKW5659 - 5 2026-06-21
SKW5407 - 5 2026-06-16
SKW5356 SkyWest Airlines 5 2026-07-18
SKW5292 SkyWest Airlines 5 2026-05-18
SKW5284 - 5 2026-06-28
SKW5264 - 5 2026-06-21
SKW5222 - 5 2026-07-15
SKW4703 - 5 2026-07-09
SKW4668 SkyWest Airlines 5 2026-06-01
SKW5918 SkyWest Airlines 4 2026-05-01
SKW5867 - 4 2026-06-21

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SKW5540 BUR → SFO Jul 26, 19:35 UTCJul 26, 21:45 UTC2h 10m
2026-07-26 SKW752U SFO → RDD Jul 26, 17:50 UTCJul 26, 18:25 UTC35m
2026-07-26 SKW4729 MRY → SFO Jul 26, 12:10 UTCJul 26, 15:15 UTC3h 5m
2026-07-25 SKW5480 GRR → ORD Jul 25, 23:30 UTCJul 26, 03:15 UTC3h 45m
2026-07-25 SKW4628 DEN → CVG Jul 25, 19:40 UTCJul 25, 21:55 UTC2h 15m
2026-07-25 SKW4628 DEN → CVG Jul 25, 19:38 UTCJul 25, 21:45 UTC2h 7m
2026-07-25 SKW5401 ORD → FWA Jul 25, 16:40 UTCJul 25, 18:40 UTC2h 0m
2026-07-25 SKW4763 IAH → SLC Jul 25, 12:25 UTCJul 25, 14:20 UTC1h 55m
2026-07-25 SKW449T DEN → SLC Jul 25, 00:15 UTCJul 25, 01:30 UTC1h 15m
2026-07-24 SKW5540 BUR → SFO Jul 24, 19:45 UTCJul 24, 21:45 UTC2h 0m
2026-07-24 SKW572M SFO → RDD Jul 24, 17:55 UTCJul 24, 18:30 UTC35m
2026-07-24 SKW5479 SFO → MRY Jul 24, 12:20 UTCJul 24, 15:35 UTC3h 15m
2026-07-24 SKW6036 SFO → SAT Jul 24, 01:50 UTCJul 24, 05:00 UTC3h 10m
2026-07-23 SKW5351 SFO → SNA Jul 23, 23:30 UTCJul 24, 00:35 UTC1h 5m
2026-07-23 SKW5440 SLC → SFO Jul 23, 21:15 UTCJul 23, 22:25 UTC1h 10m
2026-07-23 SKW5440 SLC → SFO Jul 23, 21:14 UTCJul 23, 22:23 UTC1h 9m
2026-07-23 SKW5562 SCE → ORD Jul 23, 19:15 UTCJul 23, 19:45 UTC30m
2026-07-23 SKW5562 SCE → ORD Jul 23, 18:54 UTCJul 23, 20:26 UTC1h 32m
2026-07-23 SKW5236 SBP → SFO Jul 23, 15:05 UTCJul 23, 16:15 UTC1h 10m
2026-07-23 SKW4763 IAH → SLC Jul 23, 12:25 UTCJul 23, 14:15 UTC1h 50m
2026-07-23 SKW449T DEN → SLC Jul 23, 03:45 UTCJul 23, 05:25 UTC1h 40m
2026-07-22 SKW5540 BUR → SFO Jul 22, 20:55 UTCJul 22, 23:20 UTC2h 25m
2026-07-22 SKW5540 BUR → SFO Jul 22, 20:53 UTCJul 22, 23:16 UTC2h 23m
2026-07-22 SKW572M SFO → RDD Jul 22, 19:20 UTCJul 22, 20:00 UTC40m
2026-07-22 SKW5305 CMH → IAH Jul 22, 02:20 UTCJul 22, 03:15 UTC55m
2026-07-22 SKW5305 CMH → IAH Jul 22, 02:13 UTCJul 22, 03:06 UTC53m
2026-07-22 SKW5480 GRR → ORD Jul 22, 00:05 UTCJul 22, 00:35 UTC30m
2026-07-21 SKW4628 DEN → CVG Jul 21, 19:45 UTCJul 21, 22:05 UTC2h 20m
2026-07-21 SKW4628 DEN → CVG Jul 21, 19:38 UTCJul 21, 22:03 UTC2h 25m
2026-07-21 SKW5401 SFO → ABQ Jul 21, 16:30 UTCJul 21, 18:34 UTC2h 4m
2026-07-21 SKW5401 SFO → ABQ Jul 21, 16:25 UTCJul 21, 18:35 UTC2h 10m
2026-07-21 SKW5627 - Jul 21, 13:50 UTCJul 21, 14:40 UTC50m
2026-07-21 SKW5983 SFO → SUN Jul 21, 05:33 UTCJul 21, 05:56 UTC23m
2026-07-21 SKW5983 SFO → SUN Jul 21, 05:20 UTCJul 21, 05:55 UTC35m
2026-07-21 SKW5624 SFO → ABQ Jul 21, 02:35 UTCJul 21, 03:30 UTC55m
2026-07-21 SKW5613 SFO → MRY Jul 21, 00:40 UTCJul 21, 01:40 UTC1h 0m
2026-07-20 SKW4628 - Jul 20, 20:30 UTCJul 20, 22:30 UTC2h 0m
2026-07-20 SKW5401 SFO → ABQ Jul 20, 16:35 UTCJul 20, 18:45 UTC2h 10m
2026-07-20 SKW5401 SFO → ABQ Jul 20, 16:30 UTCJul 20, 18:43 UTC2h 13m
2026-07-20 SKW5627 - Jul 20, 13:20 UTCJul 20, 14:05 UTC45m
2026-07-20 SKW5983 - Jul 20, 05:00 UTCJul 20, 05:35 UTC35m
2026-07-20 SKW5624 SFO → ABQ Jul 20, 02:30 UTCJul 20, 03:25 UTC55m
2026-07-20 SKW5624 SFO → ABQ Jul 20, 01:54 UTCJul 20, 03:52 UTC1h 58m
2026-07-19 SKW5613 SFO → MRY Jul 19, 23:50 UTCJul 20, 00:50 UTC1h 0m
2026-07-19 SKW4628 - Jul 19, 19:50 UTCJul 19, 21:50 UTC2h 0m
2026-07-19 SKW5401 SFO → ABQ Jul 19, 16:40 UTCJul 19, 18:40 UTC2h 0m
2026-07-19 SKW5596 - Jul 19, 11:40 UTCJul 19, 13:45 UTC2h 5m
2026-07-19 SKW5596 MTY → SFO Jul 19, 11:49 UTCJul 19, 15:01 UTC3h 12m
2026-07-18 SKW5242 ORD → ROC Jul 18, 23:50 UTCJul 19, 01:05 UTC1h 15m
2026-07-18 SKW5637 ORD → MDT Jul 18, 19:35 UTCJul 18, 20:45 UTC1h 10m

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 N203SY page for operator, model, and routing details .

Mode-S A19ECF frequently asked

What is Mode-S code A19ECF?
A19ECF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N203SY.
Where is Mode-S A19ECF registered?
Mode-S code A19ECF 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 A19ECF broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A19ECF, octal 50317317, decimal 10,591,951.
What flights does A19ECF operate?
Mode-S A19ECF has broadcast 20 distinct callsigns, including SKW5401, SKW5540, SKW5972, SKW5937, SKW5591.