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sensors Mode-S transponder

A691F0

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N522SD · operated by SOUTH DAKOTA STATE UNIVERSITY

Hex
A691F0
Octal
51510760
Decimal
10,916,336
Country
US
Tail
N522SD
Type
C172
Transponder active on ground
Flights observed
278
Distinct callsigns
1
Country
US
Last broadcast
59m ago

Last known position

Most recent position reported by Mode-S A691F0.

Country allocation

The ICAO 24-bit address A691F0 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
N522SD - 278 2026-07-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 N522SD - Jul 14, 17:50 UTCJul 14, 18:00 UTC10m
2026-07-14 N522SD BKX → BKX Jul 14, 15:20 UTCJul 14, 16:40 UTC1h 20m
2026-07-13 N522SD - Jul 13, 20:40 UTCJul 13, 22:00 UTC1h 20m
2026-07-13 N522SD - Jul 13, 20:25 UTCJul 13, 20:35 UTC10m
2026-07-13 N522SD BKX → BKX Jul 13, 15:20 UTCJul 13, 16:15 UTC55m
2026-07-11 N522SD BKX → BKX Jul 11, 17:15 UTCJul 11, 17:25 UTC10m
2026-07-11 N522SD BKX → BKX Jul 11, 16:50 UTCJul 11, 17:00 UTC10m
2026-07-11 N522SD - Jul 11, 16:30 UTCJul 11, 16:35 UTC5m
2026-07-11 N522SD BKX → BKX Jul 11, 16:00 UTCJul 11, 16:05 UTC5m
2026-07-11 N522SD BKX → BKX Jul 11, 15:30 UTCJul 11, 15:40 UTC10m
2026-07-11 N522SD - Jul 11, 15:05 UTCJul 11, 15:15 UTC10m
2026-07-11 N522SD BKX → BKX Jul 11, 14:35 UTCJul 11, 14:40 UTC5m
2026-07-11 N522SD - Jul 11, 14:05 UTCJul 11, 14:15 UTC10m
2026-07-11 N522SD BKX → BKX Jul 11, 13:35 UTCJul 11, 13:45 UTC10m
2026-07-10 N522SD BKX → BKX Jul 10, 00:05 UTCJul 10, 01:00 UTC55m
2026-07-09 N522SD - Jul 9, 22:55 UTCJul 9, 23:20 UTC25m
2026-07-09 N522SD - Jul 9, 22:00 UTCJul 9, 22:15 UTC15m
2026-07-09 N522SD BKX → BKX Jul 9, 18:55 UTCJul 9, 21:10 UTC2h 15m
2026-07-09 N522SD - Jul 9, 17:10 UTCJul 9, 17:25 UTC15m
2026-07-09 N522SD - Jul 9, 15:50 UTCJul 9, 16:25 UTC35m
2026-07-08 N522SD BKX → BKX Jul 8, 14:30 UTCJul 8, 15:35 UTC1h 5m
2026-07-08 N522SD BKX → BKX Jul 8, 00:35 UTCJul 8, 01:25 UTC50m
2026-07-07 N522SD BKX → BKX Jul 7, 21:05 UTCJul 7, 22:20 UTC1h 15m
2026-07-07 N522SD BKX → BKX Jul 7, 19:10 UTCJul 7, 20:15 UTC1h 5m
2026-07-07 N522SD BKX → BKX Jul 7, 15:45 UTCJul 7, 17:05 UTC1h 20m
2026-07-07 N522SD BKX → BKX Jul 7, 13:25 UTCJul 7, 14:35 UTC1h 10m
2026-07-06 N522SD BKX → BKX Jul 6, 20:30 UTCJul 6, 22:05 UTC1h 35m
2026-07-06 N522SD BKX → BKX Jul 6, 19:30 UTCJul 6, 19:35 UTC5m
2026-07-06 N522SD BKX → BKX Jul 6, 18:45 UTCJul 6, 19:25 UTC40m
2026-07-06 N522SD BKX → BKX Jul 6, 15:10 UTCJul 6, 16:45 UTC1h 35m
2026-07-06 N522SD BKX → BKX Jul 6, 12:50 UTCJul 6, 13:50 UTC1h 0m
2026-07-02 N522SD BKX → BKX Jul 2, 15:00 UTCJul 2, 16:15 UTC1h 15m
2026-07-01 N522SD - Jul 1, 22:25 UTCJul 1, 22:35 UTC10m
2026-07-01 N522SD - Jul 1, 21:05 UTCJul 1, 21:15 UTC10m
2026-07-01 N522SD BKX → BKX Jul 1, 15:50 UTCJul 1, 17:20 UTC1h 30m
2026-07-01 N522SD BKX → BKX Jul 1, 03:10 UTCJul 1, 03:50 UTC40m
2026-07-01 N522SD BKX → BKX Jul 1, 01:00 UTCJul 1, 01:55 UTC55m
2026-06-30 N522SD - Jun 30, 22:40 UTCJun 30, 23:00 UTC20m
2026-06-30 N522SD - Jun 30, 21:40 UTCJun 30, 22:00 UTC20m
2026-06-30 N522SD BKX → BKX Jun 30, 15:20 UTCJun 30, 16:40 UTC1h 20m
2026-06-30 N522SD - Jun 30, 13:45 UTCJun 30, 14:20 UTC35m
2026-06-30 N522SD BKX → BKX Jun 30, 13:20 UTCJun 30, 13:40 UTC20m
2026-06-26 N522SD BKX → BKX Jun 26, 16:54 UTCJun 26, 17:15 UTC20m
2026-06-26 N522SD BKX → BKX Jun 26, 14:55 UTCJun 26, 16:09 UTC1h 15m
2026-06-25 N522SD BKX → BKX Jun 25, 21:25 UTCJun 25, 22:45 UTC1h 20m
2026-06-25 N522SD - Jun 25, 20:14 UTCJun 25, 20:45 UTC30m
2026-06-25 N522SD - Jun 25, 17:39 UTCJun 25, 19:09 UTC1h 30m
2026-06-25 N522SD BKX → BKX Jun 25, 15:10 UTCJun 25, 16:29 UTC1h 20m
2026-06-25 N522SD - Jun 25, 14:04 UTCJun 25, 14:09 UTC5m
2026-06-25 N522SD - Jun 25, 12:40 UTCJun 25, 12:54 UTC15m

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 N522SD page for operator, model, and routing details .

Mode-S A691F0 frequently asked

What is Mode-S code A691F0?
A691F0 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N522SD.
Where is Mode-S A691F0 registered?
Mode-S code A691F0 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 A691F0 broadcasting right now?
Mode-S A691F0 is currently broadcasting from the ground.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A691F0, octal 51510760, decimal 10,916,336.
What flights does A691F0 operate?
Mode-S A691F0 has broadcast 1 distinct callsign, including N522SD.