sensors Mode-S transponder

A276DD

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N258SY · EMBRAER ERJ-170-200 (long wing) · operated by SKYWEST AIRLINES INC

Hex
A276DD
Octal
50473335
Decimal
10,647,261
Country
US
Tail
N258SY
Type
E75L
No current signal · last broadcast 1d ago
Flights observed
7
Distinct callsigns
6
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A276DD.

Country allocation

The ICAO 24-bit address A276DD 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 6 distinct

Callsign Airline Flights Last seen
SKW3801 - 2 2026-04-13
SKW3901 - 1 2026-04-13
SKW3839 - 1 2026-04-13
SKW3717 - 1 2026-04-13
SKW3618 SkyWest Airlines 1 2026-04-12
SKW160Y - 1 2026-04-13

Recent flights last 7

DateFlightRouteTakeoffLandingDuration
2026-04-13 SKW3717 SLC → TUS Apr 13, 21:20 UTCApr 13, 23:00 UTC1h 40m
2026-04-13 SKW3801 - Apr 13, 16:25 UTCApr 13, 19:45 UTC3h 20m
2026-04-13 SKW3801 - Apr 13, 15:45 UTCApr 13, 16:10 UTC25m
2026-04-13 SKW3901 - Apr 13, 12:35 UTCApr 13, 12:55 UTC20m
2026-04-13 SKW3839 - Apr 13, 03:15 UTCApr 13, 03:35 UTC20m
2026-04-13 SKW160Y - Apr 13, 01:20 UTCApr 13, 02:00 UTC40m
2026-04-12 SKW3618 ATL → SBN Apr 12, 18:00 UTCApr 12, 19:15 UTC1h 15m

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 N258SY page for operator, model, and routing details .

Mode-S A276DD frequently asked

What is Mode-S code A276DD?
A276DD is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N258SY.
Where is Mode-S A276DD registered?
Mode-S code A276DD 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 A276DD broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A276DD, octal 50473335, decimal 10,647,261.
What flights does A276DD operate?
Mode-S A276DD has broadcast 6 distinct callsigns, including SKW3801, SKW3901, SKW3839, SKW3717, SKW3618.