Apparatus

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sensors Mode-S transponder

AC01A4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N873BR · DIAMOND DA-40 Club Star · operated by EVA FLIGHT TRAINING ACADEMY

Hex
AC01A4
Octal
53000644
Decimal
11,272,612
Country
US
Tail
N873BR
Type
DA40
Broadcasting now · callsign ES803 · 2,975 ft
Flights observed
279
Distinct callsigns
2
Country
US
Last broadcast
Jul 26, 19:45 UTC

Current position

AC01A4 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address AC01A4 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 2 distinct

Callsign Airline Flights Last seen
ES803 - 260 2026-07-26
N873BR - 19 2026-07-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 ES803 MHR → MHR Jul 26, 18:30 UTCJul 26, 19:40 UTC1h 10m
2026-07-26 ES803 MHR → MHR Jul 26, 14:45 UTCJul 26, 16:30 UTC1h 45m
2026-07-25 ES803 MHR → MHR Jul 25, 19:05 UTCJul 25, 20:50 UTC1h 45m
2026-07-25 ES803 MHR → MHR Jul 25, 15:30 UTCJul 25, 16:55 UTC1h 25m
2026-07-24 ES803 MHR → MHR Jul 24, 15:15 UTCJul 24, 16:10 UTC55m
2026-07-23 ES803 MHR → MHR Jul 23, 17:05 UTCJul 23, 18:10 UTC1h 5m
2026-07-23 ES803 MHR → MHR Jul 23, 14:30 UTCJul 23, 15:50 UTC1h 20m
2026-07-22 ES803 MHR → MHR Jul 22, 18:15 UTCJul 22, 19:25 UTC1h 10m
2026-07-22 ES803 MHR → MHR Jul 22, 15:20 UTCJul 22, 16:45 UTC1h 25m
2026-07-21 ES803 MHR → MHR Jul 21, 18:30 UTCJul 21, 19:50 UTC1h 20m
2026-07-21 ES803 MHR → MHR Jul 21, 14:25 UTCJul 21, 15:25 UTC1h 0m
2026-07-20 ES803 MHR → MHR Jul 20, 20:15 UTCJul 20, 21:45 UTC1h 30m
2026-07-20 ES803 MHR → MHR Jul 20, 14:50 UTCJul 20, 16:25 UTC1h 35m
2026-07-19 ES803 MHR → MHR Jul 19, 18:10 UTCJul 19, 19:30 UTC1h 20m
2026-07-19 ES803 MHR → MHR Jul 19, 14:40 UTCJul 19, 16:00 UTC1h 20m
2026-07-18 ES803 MHR → MHR Jul 18, 18:15 UTCJul 18, 19:45 UTC1h 30m
2026-07-18 ES803 MHR → MHR Jul 18, 15:25 UTCJul 18, 16:35 UTC1h 10m
2026-07-17 ES803 MHR → MHR Jul 17, 19:49 UTCJul 17, 19:55 UTC5m
2026-07-17 ES803 MHR → MHR Jul 17, 19:05 UTCJul 17, 19:30 UTC25m
2026-07-17 ES803 MHR → MHR Jul 17, 17:30 UTCJul 17, 18:19 UTC50m
2026-07-17 ES803 MHR → MHR Jul 17, 15:05 UTCJul 17, 16:15 UTC1h 10m
2026-07-16 ES803 MHR → MHR Jul 16, 18:50 UTCJul 16, 18:59 UTC10m
2026-07-16 ES803 MHR → MHR Jul 16, 17:30 UTCJul 16, 18:05 UTC35m
2026-07-16 ES803 MHR → MHR Jul 16, 15:49 UTCJul 16, 16:00 UTC10m
2026-07-16 ES803 - Jul 16, 15:35 UTCJul 16, 15:45 UTC10m
2026-07-16 ES803 MHR → MHR Jul 16, 14:40 UTCJul 16, 15:00 UTC20m
2026-07-15 N873BR - Jul 15, 19:50 UTCJul 15, 19:55 UTC5m
2026-07-15 N873BR MCC → MHR Jul 15, 19:25 UTCJul 15, 19:40 UTC15m
2026-07-15 N873BR - Jul 15, 18:40 UTCJul 15, 19:15 UTC35m
2026-07-15 N873BR - Jul 15, 17:30 UTCJul 15, 18:05 UTC35m
2026-07-15 ES803 MHR → MHR Jul 15, 14:40 UTCJul 15, 15:55 UTC1h 15m
2026-07-14 ES803 MHR → MHR Jul 14, 22:15 UTCJul 14, 22:20 UTC5m
2026-07-14 ES803 - Jul 14, 22:00 UTCJul 14, 22:05 UTC5m
2026-07-14 ES803 - Jul 14, 21:15 UTCJul 14, 21:25 UTC10m
2026-07-14 ES803 MHR → MHR Jul 14, 20:55 UTCJul 14, 21:05 UTC10m
2026-07-14 ES803 MHR → MHR Jul 14, 17:55 UTCJul 14, 18:50 UTC55m
2026-07-14 ES803 MHR → MHR Jul 14, 16:30 UTCJul 14, 16:40 UTC10m
2026-07-14 ES803 MHR → MHR Jul 14, 16:15 UTCJul 14, 16:25 UTC10m
2026-07-14 ES803 - Jul 14, 15:45 UTCJul 14, 15:50 UTC5m
2026-07-14 ES803 MHR → MHR Jul 14, 15:10 UTCJul 14, 15:30 UTC20m
2026-07-13 ES803 MHR → MHR Jul 13, 23:05 UTCJul 14, 00:30 UTC1h 25m
2026-07-13 ES803 MHR → MHR Jul 13, 20:20 UTCJul 13, 21:30 UTC1h 10m
2026-07-13 ES803 MHR → MHR Jul 13, 18:35 UTCJul 13, 19:35 UTC1h 0m
2026-07-13 ES803 - Jul 13, 16:25 UTCJul 13, 16:40 UTC15m
2026-07-13 ES803 - Jul 13, 16:05 UTCJul 13, 16:15 UTC10m
2026-07-13 ES803 MHR → MCC Jul 13, 15:15 UTCJul 13, 16:00 UTC45m
2026-07-12 ES803 MHR → MHR Jul 12, 18:20 UTCJul 12, 18:45 UTC25m
2026-07-12 ES803 MHR → MHR Jul 12, 15:01 UTCJul 12, 16:25 UTC1h 25m
2026-07-11 ES803 MHR → MHR Jul 11, 19:20 UTCJul 11, 20:50 UTC1h 30m
2026-07-11 ES803 MHR → MHR Jul 11, 15:00 UTCJul 11, 16:30 UTC1h 30m

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 N873BR page for operator, model, and routing details .

Mode-S AC01A4 frequently asked

What is Mode-S code AC01A4?
AC01A4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N873BR.
Where is Mode-S AC01A4 registered?
Mode-S code AC01A4 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 AC01A4 broadcasting right now?
Yes. Mode-S AC01A4 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC01A4, octal 53000644, decimal 11,272,612.
What flights does AC01A4 operate?
Mode-S AC01A4 has broadcast 2 distinct callsigns, including ES803, N873BR.