Apparatus

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sensors Mode-S transponder

A7121E

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N555BG · CESSNA 525A Citation CJ2 · operated by N & E AVIATION LLC, CEJA PARTNERS LLC

Hex
A7121E
Octal
51611036
Decimal
10,949,150
Country
US
Tail
N555BG
Type
C25A
No current signal · last broadcast Jul 24, 15:45 UTC
Flights observed
63
Distinct callsigns
1
Country
US
Last broadcast
Jul 24, 15:45 UTC

Last known position

Most recent position reported by Mode-S A7121E.

Country allocation

The ICAO 24-bit address A7121E 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
N555BG - 62 2026-07-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-24 N555BG - Jul 24, 15:25 UTCJul 24, 15:45 UTC20m
2026-07-24 N555BG - Jul 24, 13:45 UTCJul 24, 14:40 UTC55m
2026-07-23 N555BG - Jul 23, 17:30 UTCJul 23, 18:30 UTC1h 0m
2026-07-23 N555BG - Jul 23, 16:05 UTCJul 23, 16:25 UTC20m
2026-07-16 N555BG - Jul 16, 14:25 UTCJul 16, 14:55 UTC30m
2026-07-16 N555BG - Jul 16, 12:34 UTCJul 16, 13:45 UTC1h 10m
2026-07-13 N555BG - Jul 13, 19:20 UTCJul 13, 19:45 UTC25m
2026-07-13 N555BG - Jul 13, 17:45 UTCJul 13, 18:35 UTC50m
2026-07-10 N555BG - Jul 10, 00:20 UTCJul 10, 01:20 UTC1h 0m
2026-07-09 N555BG - Jul 9, 23:00 UTCJul 9, 23:30 UTC30m
2026-07-08 N555BG - Jul 8, 15:20 UTCJul 8, 16:20 UTC1h 0m
2026-07-07 N555BG - Jul 7, 14:10 UTCJul 7, 14:50 UTC40m
2026-06-25 N555BG - Jun 25, 20:25 UTCJun 25, 20:54 UTC30m
2026-06-25 N555BG - Jun 25, 17:25 UTCJun 25, 17:44 UTC20m
2026-06-22 N555BG - Jun 22, 21:19 UTCJun 22, 22:19 UTC1h 0m
2026-06-22 N555BG - Jun 22, 19:49 UTCJun 22, 20:19 UTC30m
2026-06-19 N555BG - Jun 19, 00:00 UTCJun 19, 00:24 UTC24m
2026-06-18 N555BG - Jun 18, 22:05 UTCJun 18, 22:45 UTC40m
2026-06-15 N555BG - Jun 15, 15:55 UTCJun 15, 16:15 UTC20m
2026-06-15 N555BG - Jun 15, 14:24 UTCJun 15, 15:04 UTC40m
2026-06-14 N555BG - Jun 14, 22:25 UTCJun 14, 23:25 UTC1h 0m
2026-06-14 N555BG - Jun 14, 18:50 UTCJun 14, 19:55 UTC1h 5m
2026-06-12 N555BG - Jun 12, 20:55 UTCJun 12, 21:50 UTC55m
2026-06-12 N555BG - Jun 12, 16:20 UTCJun 12, 17:05 UTC45m
2026-06-11 N555BG - Jun 11, 22:05 UTCJun 11, 23:45 UTC1h 40m
2026-06-11 N555BG - Jun 11, 21:10 UTCJun 11, 21:30 UTC20m
2026-06-10 N555BG - Jun 10, 14:55 UTCJun 10, 15:40 UTC45m
2026-06-08 N555BG - Jun 8, 00:30 UTCJun 8, 02:50 UTC2h 20m
2026-06-05 N555BG - Jun 5, 21:45 UTCJun 5, 23:55 UTC2h 10m
2026-06-04 N555BG - Jun 4, 22:55 UTCJun 4, 23:50 UTC55m
2026-06-04 N555BG - Jun 4, 19:40 UTCJun 4, 20:35 UTC55m
2026-06-02 N555BG - Jun 2, 17:55 UTCJun 2, 18:55 UTC1h 0m
2026-06-02 N555BG - Jun 2, 12:45 UTCJun 2, 13:45 UTC1h 0m
2026-05-31 N555BG - May 31, 23:10 UTCJun 1, 00:10 UTC1h 0m
2026-05-31 N555BG - May 31, 19:15 UTCMay 31, 19:55 UTC40m
2026-05-29 N555BG - May 29, 22:35 UTCMay 29, 23:00 UTC25m
2026-05-29 N555BG - May 29, 18:10 UTCMay 29, 18:50 UTC40m
2026-05-29 N555BG - May 29, 17:15 UTCMay 29, 17:30 UTC15m
2026-05-21 N555BG - May 21, 18:40 UTCMay 21, 19:35 UTC55m
2026-05-21 N555BG - May 21, 13:15 UTCMay 21, 13:50 UTC35m
2026-05-21 N555BG - May 21, 00:00 UTCMay 21, 00:55 UTC55m
2026-05-20 N555BG - May 20, 22:10 UTCMay 20, 22:45 UTC35m
2026-05-12 N555BG - May 12, 15:15 UTCMay 12, 20:05 UTC4h 50m
2026-05-10 N555BG - May 10, 20:30 UTCMay 10, 21:00 UTC30m
2026-05-10 N555BG - May 10, 19:09 UTCMay 10, 19:54 UTC45m
2026-05-10 N555BG - May 10, 18:05 UTCMay 10, 18:29 UTC25m
2026-05-07 N555BG - May 7, 23:45 UTCMay 8, 00:40 UTC55m
2026-05-07 N555BG - May 7, 18:20 UTCMay 7, 21:55 UTC3h 35m
2026-05-03 N555BG - May 3, 20:35 UTCMay 3, 21:54 UTC1h 20m
2026-05-03 N555BG - May 3, 18:50 UTCMay 3, 19:55 UTC1h 5m

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 N555BG page for operator, model, and routing details .

Mode-S A7121E frequently asked

What is Mode-S code A7121E?
A7121E is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N555BG.
Where is Mode-S A7121E registered?
Mode-S code A7121E 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 A7121E broadcasting right now?
No active broadcast right now. Last signal was Jul 24, 15:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A7121E, octal 51611036, decimal 10,949,150.
What flights does A7121E operate?
Mode-S A7121E has broadcast 1 distinct callsign, including N555BG.