Apparatus

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sensors Mode-S transponder

A6EF66

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N546ND · CESSNA 172 Skyhawk · operated by SPARTAN EDUCATION LLC

Hex
A6EF66
Octal
51567546
Decimal
10,940,262
Country
US
Tail
N546ND
Type
C172
No current signal · last broadcast 5h ago
Flights observed
56
Distinct callsigns
1
Country
US
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S A6EF66.

Country allocation

The ICAO 24-bit address A6EF66 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 1 distinct

Callsign Airline Flights Last seen
N546ND - 56 2026-05-29

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-29 N546ND BJC → BJC May 29, 19:20 UTCMay 29, 20:05 UTC45m
2026-05-28 N546ND BJC → BJC May 28, 18:20 UTCMay 28, 19:00 UTC40m
2026-05-28 N546ND BJC → BJC May 28, 12:55 UTCMay 28, 13:40 UTC45m
2026-05-27 N546ND BJC → BJC May 27, 17:55 UTCMay 27, 19:30 UTC1h 35m
2026-05-27 N546ND BJC → BJC May 27, 15:20 UTCMay 27, 16:25 UTC1h 5m
2026-05-27 N546ND BJC → BJC May 27, 12:25 UTCMay 27, 14:00 UTC1h 35m
2026-05-26 N546ND BJC → BJC May 26, 18:59 UTCMay 26, 20:00 UTC1h 0m
2026-05-26 N546ND BJC → BJC May 26, 15:54 UTCMay 26, 17:35 UTC1h 40m
2026-05-25 N546ND BJC → BJC May 25, 16:15 UTCMay 25, 17:50 UTC1h 35m
2026-05-24 N546ND BJC → BJC May 24, 16:50 UTCMay 24, 18:30 UTC1h 40m
2026-05-23 N546ND BJC → BJC May 23, 17:40 UTCMay 23, 18:35 UTC55m
2026-05-23 N546ND BJC → BJC May 23, 15:05 UTCMay 23, 16:25 UTC1h 20m
2026-05-22 N546ND BJC → BJC May 22, 20:10 UTCMay 22, 21:40 UTC1h 30m
2026-05-22 N546ND BJC → BJC May 22, 18:15 UTCMay 22, 19:20 UTC1h 5m
2026-05-22 N546ND BJC → BJC May 22, 14:25 UTCMay 22, 15:45 UTC1h 20m
2026-05-17 N546ND BJC → BJC May 17, 16:15 UTCMay 17, 17:10 UTC55m
2026-05-16 N546ND BJC → BJC May 16, 17:50 UTCMay 16, 19:05 UTC1h 15m
2026-05-15 N546ND BJC → BJC May 15, 16:10 UTCMay 15, 17:45 UTC1h 35m
2026-05-14 N546ND BJC → BJC May 14, 14:45 UTCMay 14, 15:40 UTC55m
2026-05-12 N546ND BJC → BJC May 12, 22:15 UTCMay 12, 22:55 UTC40m
2026-05-12 N546ND BJC → BJC May 12, 19:50 UTCMay 12, 20:40 UTC50m
2026-05-12 N546ND BJC → BJC May 12, 17:10 UTCMay 12, 18:40 UTC1h 30m
2026-05-12 N546ND BJC → BJC May 12, 14:05 UTCMay 12, 15:01 UTC55m
2026-05-10 N546ND BJC → BJC May 10, 20:25 UTCMay 10, 21:49 UTC1h 25m
2026-05-09 N546ND BJC → BJC May 9, 14:20 UTCMay 9, 15:20 UTC1h 0m
2026-05-09 N546ND BJC → BJC May 9, 01:20 UTCMay 9, 02:20 UTC1h 0m
2026-05-08 N546ND - May 8, 23:20 UTCMay 8, 23:40 UTC20m
2026-05-08 N546ND - May 8, 22:45 UTCMay 8, 23:15 UTC30m
2026-05-08 N546ND BJC → BJC May 8, 20:00 UTCMay 8, 21:10 UTC1h 10m
2026-05-08 N546ND BJC → BJC May 8, 18:00 UTCMay 8, 18:10 UTC10m
2026-05-08 N546ND BJC → BJC May 8, 17:45 UTCMay 8, 17:55 UTC10m
2026-05-07 N546ND BJC → BJC May 7, 19:10 UTCMay 7, 20:15 UTC1h 5m
2026-05-07 N546ND BJC → BJC May 7, 17:15 UTCMay 7, 17:45 UTC30m
2026-05-04 N546ND - May 4, 19:10 UTCMay 4, 19:30 UTC20m
2026-05-04 N546ND - May 4, 18:10 UTCMay 4, 19:05 UTC56m
2026-05-02 N546ND BJC → BJC May 2, 16:45 UTCMay 2, 17:55 UTC1h 10m
2026-05-02 N546ND BJC → BJC May 2, 14:20 UTCMay 2, 15:25 UTC1h 5m
2026-05-01 N546ND BJC → BJC May 1, 15:40 UTCMay 1, 16:45 UTC1h 5m
2026-05-01 N546ND BJC → BJC May 1, 13:35 UTCMay 1, 14:30 UTC55m
2026-04-22 N546ND BJC → BJC Apr 22, 01:00 UTCApr 22, 01:45 UTC45m
2026-04-21 N546ND BJC → BJC Apr 21, 21:50 UTCApr 21, 23:10 UTC1h 20m
2026-04-21 N546ND BJC → BJC Apr 21, 19:25 UTCApr 21, 20:50 UTC1h 25m
2026-04-21 N546ND BJC → BJC Apr 21, 16:45 UTCApr 21, 18:25 UTC1h 40m
2026-04-21 N546ND BJC → BJC Apr 21, 03:10 UTCApr 21, 04:00 UTC50m
2026-04-20 N546ND - Apr 20, 22:55 UTCApr 20, 23:45 UTC50m
2026-04-20 N546ND - Apr 20, 20:50 UTCApr 20, 21:40 UTC50m
2026-04-20 N546ND BJC → BJC Apr 20, 18:35 UTCApr 20, 19:40 UTC1h 5m
2026-04-20 N546ND - Apr 20, 16:25 UTCApr 20, 17:00 UTC35m
2026-04-20 N546ND - Apr 20, 15:45 UTCApr 20, 16:05 UTC20m
2026-04-16 N546ND - Apr 16, 23:20 UTCApr 17, 00:10 UTC50m

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 N546ND page for operator, model, and routing details .

Mode-S A6EF66 frequently asked

What is Mode-S code A6EF66?
A6EF66 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N546ND.
Where is Mode-S A6EF66 registered?
Mode-S code A6EF66 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 A6EF66 broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A6EF66, octal 51567546, decimal 10,940,262.
What flights does A6EF66 operate?
Mode-S A6EF66 has broadcast 1 distinct callsign, including N546ND.