Apparatus

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sensors Mode-S transponder

A666F9

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N511US · operated by TECNAM US INC

Hex
A666F9
Octal
51463371
Decimal
10,905,337
Country
US
Tail
N511US
Type
SIRA
No current signal · last broadcast Jul 18, 20:55 UTC
Flights observed
35
Distinct callsigns
1
Country
US
Last broadcast
Jul 18, 20:55 UTC

Last known position

Most recent position reported by Mode-S A666F9.

Country allocation

The ICAO 24-bit address A666F9 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
N511US - 35 2026-07-18

Recent flights last 35

DateFlightRouteTakeoffLandingDuration
2026-07-18 N511US - Jul 18, 20:20 UTCJul 18, 20:55 UTC35m
2026-07-18 N511US - Jul 18, 15:40 UTCJul 18, 17:10 UTC1h 30m
2026-07-18 N511US - Jul 18, 12:30 UTCJul 18, 13:45 UTC1h 15m
2026-07-17 N511US - Jul 17, 17:35 UTCJul 17, 18:05 UTC30m
2026-07-17 N511US - Jul 17, 13:29 UTCJul 17, 15:29 UTC2h 0m
2026-07-17 N511US - Jul 17, 01:05 UTCJul 17, 01:29 UTC25m
2026-07-16 N511US - Jul 16, 23:10 UTCJul 16, 23:59 UTC50m
2026-07-16 N511US - Jul 16, 18:25 UTCJul 16, 20:19 UTC1h 55m
2026-07-07 N511US - Jul 7, 19:35 UTCJul 7, 20:00 UTC25m
2026-07-07 N511US - Jul 7, 18:20 UTCJul 7, 19:00 UTC40m
2026-07-07 N511US - Jul 7, 17:30 UTCJul 7, 17:45 UTC15m
2026-07-05 N511US - Jul 5, 18:40 UTCJul 5, 19:10 UTC30m
2026-07-05 N511US - Jul 5, 16:20 UTCJul 5, 16:50 UTC30m
2026-06-26 N511US - Jun 26, 16:14 UTCJun 26, 16:39 UTC25m
2026-06-26 N511US - Jun 26, 14:59 UTCJun 26, 15:34 UTC35m
2026-06-25 N511US - Jun 25, 17:54 UTCJun 25, 18:19 UTC25m
2026-06-25 N511US - Jun 25, 16:24 UTCJun 25, 16:45 UTC20m
2026-06-22 N511US - Jun 22, 19:34 UTCJun 22, 20:30 UTC55m
2026-06-20 N511US - Jun 20, 17:59 UTCJun 20, 18:14 UTC15m
2026-06-19 N511US - Jun 19, 17:24 UTCJun 19, 17:44 UTC20m
2026-06-18 N511US - Jun 18, 21:15 UTCJun 18, 21:50 UTC35m
2026-06-18 N511US - Jun 18, 16:20 UTCJun 18, 16:40 UTC20m
2026-06-18 N511US - Jun 18, 05:05 UTCJun 18, 06:10 UTC1h 5m
2026-06-18 N511US - Jun 18, 00:50 UTCJun 18, 01:50 UTC1h 0m
2026-06-18 N511US - Jun 18, 00:05 UTCJun 18, 00:20 UTC15m
2026-06-17 N511US - Jun 17, 18:05 UTCJun 17, 20:25 UTC2h 20m
2026-06-17 N511US - Jun 17, 16:20 UTCJun 17, 17:30 UTC1h 10m
2026-05-22 N511US - May 22, 19:45 UTCMay 22, 20:15 UTC30m
2026-05-19 N511US - May 19, 19:00 UTCMay 19, 19:50 UTC50m
2026-04-20 N511US - Apr 20, 15:50 UTCApr 20, 16:05 UTC15m
2026-04-20 N511US - Apr 20, 15:25 UTCApr 20, 15:40 UTC15m
2026-04-20 N511US - Apr 20, 14:30 UTCApr 20, 14:45 UTC15m
2026-04-14 N511US - Apr 14, 10:50 UTCApr 14, 11:30 UTC40m
2026-04-14 N511US - Apr 14, 10:40 UTCApr 14, 11:05 UTC25m
2026-04-13 N511US - Apr 13, 22:40 UTCApr 13, 23:00 UTC20m

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 N511US page for operator, model, and routing details .

Mode-S A666F9 frequently asked

What is Mode-S code A666F9?
A666F9 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N511US.
Where is Mode-S A666F9 registered?
Mode-S code A666F9 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 A666F9 broadcasting right now?
No active broadcast right now. Last signal was Jul 18, 20:55 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A666F9, octal 51463371, decimal 10,905,337.
What flights does A666F9 operate?
Mode-S A666F9 has broadcast 1 distinct callsign, including N511US.