sensors Mode-S transponder

AC03EF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N87303 · EMBRAER ERJ-170-200 (long wing) · operated by UNITED AIRLINES INC

Hex
AC03EF
Octal
53001757
Decimal
11,273,199
Country
US
Tail
N87303
Type
E75L
No current signal · last broadcast 1d ago
Flights observed
8
Distinct callsigns
5
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S AC03EF.

Country allocation

The ICAO 24-bit address AC03EF 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 5 distinct

Callsign Airline Flights Last seen
ASH4022 Mesa Airlines 3 2026-04-13
ASH6114 - 2 2026-04-13
ASH6190 Mesa Airlines 1 2026-04-13
ASH4064 - 1 2026-04-13
ASH3992 - 1 2026-04-13

Recent flights last 8

DateFlightRouteTakeoffLandingDuration
2026-04-13 ASH6190 YOW → IAD Apr 13, 18:00 UTCApr 13, 19:00 UTC1h 0m
2026-04-13 ASH4064 - Apr 13, 13:10 UTCApr 13, 15:30 UTC2h 20m
2026-04-13 ASH3992 - Apr 13, 10:15 UTCApr 13, 11:10 UTC55m
2026-04-13 ASH4022 LGA → IAD Apr 13, 04:20 UTCApr 13, 04:30 UTC10m
2026-04-13 ASH4022 LGA → IAD Apr 13, 03:55 UTCApr 13, 04:30 UTC35m
2026-04-13 ASH4022 LGA → IAD Apr 13, 03:16 UTCApr 13, 04:01 UTC45m
2026-04-13 ASH6114 - Apr 13, 00:20 UTCApr 13, 00:45 UTC25m
2026-04-13 ASH6114 - Apr 13, 00:05 UTCApr 13, 00:46 UTC41m

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 N87303 page for operator, model, and routing details .

Mode-S AC03EF frequently asked

What is Mode-S code AC03EF?
AC03EF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N87303.
Where is Mode-S AC03EF registered?
Mode-S code AC03EF 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 AC03EF 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 AC03EF, octal 53001757, decimal 11,273,199.
What flights does AC03EF operate?
Mode-S AC03EF has broadcast 5 distinct callsigns, including ASH4022, ASH6114, ASH6190, ASH4064, ASH3992.