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sensors Mode-S transponder

A646B3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N503SP · CESSNA 172 Skyhawk · operated by NEW HORIZON AVIATION INC

Hex
A646B3
Octal
51443263
Decimal
10,897,075
Country
US
Tail
N503SP
Type
C172
No current signal · last broadcast 13d ago
Flights observed
206
Distinct callsigns
1
Country
US
Last broadcast
13d ago

Last known position

Most recent position reported by Mode-S A646B3.

Country allocation

The ICAO 24-bit address A646B3 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
N503SP - 206 2026-07-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 N503SP - Jul 26, 18:05 UTCJul 26, 19:15 UTC1h 10m
2026-07-26 N503SP - Jul 26, 14:55 UTCJul 26, 15:20 UTC25m
2026-07-25 N503SP OWD → OWD Jul 25, 19:50 UTCJul 25, 20:40 UTC50m
2026-07-25 N503SP - Jul 25, 17:40 UTCJul 25, 18:55 UTC1h 15m
2026-07-23 N503SP - Jul 23, 18:00 UTCJul 23, 19:20 UTC1h 20m
2026-07-23 N503SP OWD → OWD Jul 23, 15:20 UTCJul 23, 16:35 UTC1h 15m
2026-07-21 N503SP OWD → OWD Jul 21, 19:05 UTCJul 21, 19:30 UTC25m
2026-07-21 N503SP - Jul 21, 15:30 UTCJul 21, 16:35 UTC1h 5m
2026-07-21 N503SP - Jul 21, 13:05 UTCJul 21, 14:20 UTC1h 15m
2026-07-20 N503SP - Jul 20, 15:15 UTCJul 20, 16:35 UTC1h 20m
2026-07-19 N503SP OWD → OWD Jul 19, 15:05 UTCJul 19, 15:55 UTC50m
2026-07-19 N503SP - Jul 19, 12:30 UTCJul 19, 14:15 UTC1h 45m
2026-07-18 N503SP - Jul 18, 16:10 UTCJul 18, 16:50 UTC40m
2026-07-18 N503SP - Jul 18, 13:05 UTCJul 18, 14:20 UTC1h 15m
2026-07-16 N503SP - Jul 16, 21:19 UTCJul 16, 21:45 UTC25m
2026-07-16 N503SP OWD → PVD Jul 16, 20:15 UTCJul 16, 20:35 UTC20m
2026-07-16 N503SP - Jul 16, 17:49 UTCJul 16, 18:44 UTC55m
2026-07-16 N503SP OWD → OWD Jul 16, 16:09 UTCJul 16, 16:40 UTC30m
2026-07-15 N503SP - Jul 15, 20:20 UTCJul 15, 21:30 UTC1h 10m
2026-07-15 N503SP - Jul 15, 19:15 UTCJul 15, 19:30 UTC15m
2026-07-15 N503SP - Jul 15, 17:50 UTCJul 15, 18:10 UTC20m
2026-07-15 N503SP - Jul 15, 15:20 UTCJul 15, 16:45 UTC1h 25m
2026-07-15 N503SP - Jul 15, 12:50 UTCJul 15, 14:00 UTC1h 10m
2026-07-14 N503SP - Jul 14, 20:45 UTCJul 14, 21:40 UTC55m
2026-07-14 N503SP - Jul 14, 17:55 UTCJul 14, 19:10 UTC1h 15m
2026-07-14 N503SP - Jul 14, 15:10 UTCJul 14, 16:30 UTC1h 20m
2026-07-14 N503SP - Jul 14, 12:55 UTCJul 14, 13:45 UTC50m
2026-07-13 N503SP - Jul 13, 15:15 UTCJul 13, 16:30 UTC1h 15m
2026-07-13 N503SP - Jul 13, 12:50 UTCJul 13, 14:15 UTC1h 25m
2026-07-12 N503SP - Jul 12, 17:35 UTCJul 12, 19:05 UTC1h 30m
2026-07-11 N503SP - Jul 11, 20:20 UTCJul 11, 21:10 UTC50m
2026-07-11 N503SP - Jul 11, 15:15 UTCJul 11, 16:35 UTC1h 20m
2026-07-11 N503SP - Jul 11, 13:10 UTCJul 11, 14:15 UTC1h 5m
2026-07-09 N503SP - Jul 9, 20:35 UTCJul 9, 21:40 UTC1h 5m
2026-07-09 N503SP - Jul 9, 18:05 UTCJul 9, 19:10 UTC1h 5m
2026-07-09 N503SP - Jul 9, 15:15 UTCJul 9, 16:35 UTC1h 20m
2026-07-09 N503SP - Jul 9, 12:50 UTCJul 9, 14:25 UTC1h 35m
2026-07-08 N503SP OWD → OWD Jul 8, 20:10 UTCJul 8, 20:55 UTC45m
2026-07-08 N503SP - Jul 8, 17:45 UTCJul 8, 19:00 UTC1h 15m
2026-07-08 N503SP - Jul 8, 12:50 UTCJul 8, 14:10 UTC1h 20m
2026-07-07 N503SP - Jul 7, 15:20 UTCJul 7, 17:00 UTC1h 40m
2026-07-06 N503SP - Jul 6, 20:10 UTCJul 6, 21:25 UTC1h 15m
2026-07-06 N503SP - Jul 6, 14:50 UTCJul 6, 15:30 UTC40m
2026-07-05 N503SP - Jul 5, 20:10 UTCJul 5, 21:15 UTC1h 5m
2026-07-05 N503SP OWD → OWD Jul 5, 17:40 UTCJul 5, 18:55 UTC1h 15m
2026-07-05 N503SP - Jul 5, 15:20 UTCJul 5, 16:25 UTC1h 5m
2026-07-05 N503SP OWD → OWD Jul 5, 12:45 UTCJul 5, 13:40 UTC55m
2026-07-03 N503SP OWD → OWD Jul 3, 20:10 UTCJul 3, 21:40 UTC1h 30m
2026-07-03 N503SP OWD → OWD Jul 3, 17:55 UTCJul 3, 19:00 UTC1h 5m
2026-07-03 N503SP - Jul 3, 15:15 UTCJul 3, 15:55 UTC40m

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 N503SP page for operator, model, and routing details .

Mode-S A646B3 frequently asked

What is Mode-S code A646B3?
A646B3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N503SP.
Where is Mode-S A646B3 registered?
Mode-S code A646B3 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 A646B3 broadcasting right now?
No active broadcast right now. Last signal was 13d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A646B3, octal 51443263, decimal 10,897,075.
What flights does A646B3 operate?
Mode-S A646B3 has broadcast 1 distinct callsign, including N503SP.