Apparatus

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sensors Mode-S transponder

3951C1

ICAO 24-bit transponder address · allocated to France

Currently assigned to F-GUOB · BOEING 777-200LR

Hex
3951C1
Octal
16250701
Decimal
3,756,481
Country
FR
Tail
F-GUOB
Type
B77L
Transponder active on ground
Flights observed
186
Distinct callsigns
18
Country
FR
Last broadcast
Jul 26, 20:45 UTC

Last known position

Most recent position reported by Mode-S 3951C1.

Country allocation

The ICAO 24-bit address 3951C1 falls within the block assigned to France (FR) by ICAO Annex 10, Volume III. Every aircraft registered in France 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 18 distinct

Callsign Airline Flights Last seen
AFR6733 Air France 25 2026-07-24
AFR6732 Air France 17 2026-07-23
AFR6727 Air France 15 2026-07-23
AFR6726 - 15 2026-07-22
AFR6721 - 12 2026-06-24
AFR6728 Air France 11 2026-06-25
AFR6720 - 11 2026-06-23
AFR6740 Air France 10 2026-07-26
AFR6741 - 9 2026-07-20
AFR6729 Air France 9 2026-06-26
AFR6735 Air France 8 2026-07-25
AFR6723 - 8 2026-06-27
AFR6738 Air France 7 2026-07-21
AFR6722 - 7 2026-06-26
AFR6739 - 6 2026-07-22
AFR6737 Air France 6 2026-07-26
AFR6736 Air France 6 2026-07-25
AFR6734 Air France 4 2026-07-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 AFR6740 CDG → ORD Jul 26, 19:50 UTCJul 26, 20:45 UTC55m
2026-07-26 AFR6737 ORD → CDG Jul 26, 08:55 UTCJul 26, 16:15 UTC7h 20m
2026-07-25 AFR6736 CDG → ORD Jul 25, 21:40 UTCJul 26, 05:40 UTC8h 0m
2026-07-25 AFR6735 DUB → CDG Jul 25, 17:20 UTCJul 25, 18:35 UTC1h 15m
2026-07-25 AFR6735 DUB → CDG Jul 25, 08:35 UTCJul 25, 15:00 UTC6h 25m
2026-07-24 AFR6734 CDG → ORD Jul 24, 20:25 UTCJul 25, 04:35 UTC8h 10m
2026-07-24 AFR6733 ORD → CDG Jul 24, 16:40 UTCJul 24, 17:50 UTC1h 10m
2026-07-24 AFR6733 ORD → CDG Jul 24, 08:25 UTCJul 24, 14:50 UTC6h 25m
2026-07-23 AFR6732 CDG → ORD Jul 23, 19:55 UTCJul 24, 04:00 UTC8h 5m
2026-07-23 AFR6727 BOM → CDG Jul 23, 07:25 UTCJul 23, 16:20 UTC8h 55m
2026-07-22 AFR6726 - Jul 22, 18:40 UTCJul 23, 03:00 UTC8h 20m
2026-07-22 AFR6739 - Jul 22, 10:20 UTCJul 22, 15:25 UTC5h 5m
2026-07-21 AFR6738 CDG → ORD Jul 21, 20:15 UTCJul 22, 04:35 UTC8h 20m
2026-07-21 AFR6733 ORD → CDG Jul 21, 15:00 UTCJul 21, 16:10 UTC1h 10m
2026-07-21 AFR6733 ORD → CDG Jul 21, 07:10 UTCJul 21, 13:40 UTC6h 30m
2026-07-20 AFR6732 CDG → ORD Jul 20, 20:20 UTCJul 21, 04:20 UTC8h 0m
2026-07-20 AFR6741 - Jul 20, 08:10 UTCJul 20, 15:45 UTC7h 35m
2026-07-19 AFR6740 CDG → ORD Jul 19, 20:40 UTCJul 20, 04:50 UTC8h 10m
2026-07-19 AFR6737 ORD → CDG Jul 19, 10:30 UTCJul 19, 18:05 UTC7h 35m
2026-07-18 AFR6736 CDG → ORD Jul 18, 21:25 UTCJul 19, 06:05 UTC8h 40m
2026-07-17 AFR6733 - Jul 17, 19:20 UTCJul 17, 20:35 UTC1h 15m
2026-07-17 AFR6733 - Jul 17, 10:25 UTCJul 17, 17:20 UTC6h 55m
2026-07-17 AFR6732 - Jul 17, 04:35 UTCJul 17, 04:54 UTC20m
2026-07-16 AFR6732 - Jul 16, 20:55 UTCJul 17, 04:29 UTC7h 35m
2026-07-16 AFR6727 - Jul 16, 08:25 UTCJul 16, 17:35 UTC9h 10m
2026-07-15 AFR6726 - Jul 15, 20:00 UTCJul 16, 04:25 UTC8h 25m
2026-07-15 AFR6739 ORD → CDG Jul 15, 07:40 UTCJul 15, 15:20 UTC7h 40m
2026-07-14 AFR6738 - Jul 14, 20:20 UTCJul 15, 04:30 UTC8h 9m
2026-07-14 AFR6733 - Jul 14, 06:00 UTCJul 14, 13:50 UTC7h 50m
2026-07-13 AFR6732 - Jul 13, 18:40 UTCJul 14, 02:40 UTC8h 0m
2026-07-13 AFR6741 - Jul 13, 07:10 UTCJul 13, 15:05 UTC7h 55m
2026-07-12 AFR6740 - Jul 12, 20:10 UTCJul 13, 04:15 UTC8h 5m
2026-07-12 AFR6737 ORD → CDG Jul 12, 08:55 UTCJul 12, 16:35 UTC7h 40m
2026-07-11 AFR6736 - Jul 11, 21:55 UTCJul 12, 06:01 UTC8h 5m
2026-07-11 AFR6735 - Jul 11, 17:45 UTCJul 11, 19:00 UTC1h 15m
2026-07-11 AFR6735 - Jul 11, 08:40 UTCJul 11, 15:15 UTC6h 35m
2026-07-10 AFR6734 - Jul 10, 20:50 UTCJul 11, 05:10 UTC8h 20m
2026-07-10 AFR6733 - Jul 10, 16:30 UTCJul 10, 17:45 UTC1h 15m
2026-07-10 AFR6733 - Jul 10, 08:00 UTCJul 10, 14:40 UTC6h 40m
2026-07-09 AFR6732 - Jul 9, 19:30 UTCJul 10, 04:45 UTC9h 15m
2026-07-09 AFR6727 - Jul 9, 07:45 UTCJul 9, 16:50 UTC9h 5m
2026-07-08 AFR6726 - Jul 8, 19:35 UTCJul 9, 03:40 UTC8h 5m
2026-07-08 AFR6739 ORD → CDG Jul 8, 09:35 UTCJul 8, 17:15 UTC7h 40m
2026-07-07 AFR6738 - Jul 7, 22:20 UTCJul 8, 06:25 UTC8h 5m
2026-07-07 AFR6733 - Jul 7, 18:45 UTCJul 7, 20:05 UTC1h 20m
2026-07-07 AFR6733 ORD → PIK Jul 7, 09:00 UTCJul 7, 15:45 UTC6h 45m
2026-07-06 AFR6732 - Jul 6, 19:40 UTCJul 7, 03:45 UTC8h 5m
2026-07-06 AFR6741 ORD → CDG Jul 6, 07:00 UTCJul 6, 14:35 UTC7h 35m
2026-07-05 AFR6740 - Jul 5, 19:40 UTCJul 6, 03:50 UTC8h 10m
2026-07-05 AFR6737 - Jul 5, 09:00 UTCJul 5, 16:25 UTC7h 25m

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 F-GUOB page for operator, model, and routing details .

Mode-S 3951C1 frequently asked

What is Mode-S code 3951C1?
3951C1 is an ICAO 24-bit transponder address. Allocated to France. Assigned to F-GUOB.
Where is Mode-S 3951C1 registered?
Mode-S code 3951C1 is allocated to France (FR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 3951C1 broadcasting right now?
Mode-S 3951C1 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 3951C1, octal 16250701, decimal 3,756,481.
What flights does 3951C1 operate?
Mode-S 3951C1 has broadcast 18 distinct callsigns, including AFR6733, AFR6732, AFR6727, AFR6726, AFR6721.