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
- Flights observed
- 81
- Distinct callsigns
- 17
- Country
- FR
- Last broadcast
- 5h ago
Current position
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 17 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| AFR6721 | Air France | 9 | 2026-05-25 |
| AFR6727 | Air France | 8 | 2026-05-28 |
| AFR6720 | Air France | 8 | 2026-05-25 |
| AFR6733 | Air France | 7 | 2026-05-29 |
| AFR6728 | Air France | 7 | 2026-05-21 |
| AFR6729 | Air France | 6 | 2026-05-22 |
| AFR6726 | Air France | 6 | 2026-05-27 |
| AFR6723 | Air France | 6 | 2026-05-23 |
| AFR6732 | Air France | 5 | 2026-05-28 |
| AFR6722 | Air France | 5 | 2026-05-22 |
| AFR6741 | Air France | 3 | 2026-05-18 |
| AFR6740 | Air France | 3 | 2026-05-17 |
| AFR6738 | Air France | 3 | 2026-05-27 |
| AFR6739 | Air France | 2 | 2026-05-27 |
| AFR6737 | Air France | 1 | 2026-04-19 |
| AFR6736 | Air France | 1 | 2026-04-18 |
| AFR6734 | Air France | 1 | 2026-05-29 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | AFR6734 | CDG → ORD | May 29, 20:50 UTC | May 29, 22:30 UTC | 1h 40m |
| 2026-05-29 | AFR6733 | ORD → CDG | May 29, 10:10 UTC | May 29, 17:55 UTC | 7h 45m |
| 2026-05-28 | AFR6732 | CDG → ORD | May 28, 20:15 UTC | May 29, 04:20 UTC | 8h 5m |
| 2026-05-28 | AFR6727 | BOM → CDG | May 28, 08:00 UTC | May 28, 17:30 UTC | 9h 30m |
| 2026-05-27 | AFR6726 | CDG → BOM | May 27, 18:50 UTC | May 28, 03:05 UTC | 8h 15m |
| 2026-05-27 | AFR6739 | PIK → CDG | May 27, 08:00 UTC | May 27, 15:40 UTC | 7h 40m |
| 2026-05-27 | AFR6738 | CDG → ORD | May 27, 02:34 UTC | May 27, 04:55 UTC | 2h 20m |
| 2026-05-26 | AFR6738 | CDG → ORD | May 26, 20:29 UTC | May 27, 02:09 UTC | 5h 40m |
| 2026-05-25 | AFR6721 | GDL → CDG | May 25, 17:40 UTC | May 26, 03:25 UTC | 9h 44m |
| 2026-05-25 | AFR6721 | GDL → CDG | May 25, 13:20 UTC | May 25, 13:35 UTC | 15m |
| 2026-05-25 | AFR6720 | CDG → MEX | May 25, 05:45 UTC | May 25, 08:45 UTC | 3h 0m |
| 2026-05-23 | AFR6723 | MEX → CDG | May 23, 20:25 UTC | May 24, 06:50 UTC | 10h 25m |
| 2026-05-22 | AFR6722 | CDG → MEX | May 22, 13:05 UTC | May 23, 00:25 UTC | 11h 20m |
| 2026-05-22 | AFR6729 | PEK → CDG | May 22, 05:35 UTC | May 22, 10:05 UTC | 4h 30m |
| 2026-05-21 | AFR6728 | CDG → PEK | May 21, 17:50 UTC | May 21, 18:10 UTC | 20m |
| 2026-05-21 | AFR6728 | CDG → PEK | May 21, 07:35 UTC | May 21, 12:00 UTC | 4h 25m |
| 2026-05-20 | AFR6721 | GDL → CDG | May 20, 18:10 UTC | May 21, 03:40 UTC | 9h 30m |
| 2026-05-19 | AFR6720 | CDG → MEX | May 19, 21:35 UTC | May 20, 08:55 UTC | 11h 21m |
| 2026-05-19 | AFR6733 | ORD → CDG | May 19, 15:05 UTC | May 19, 16:30 UTC | 1h 25m |
| 2026-05-19 | AFR6733 | ORD → CDG | May 19, 06:30 UTC | May 19, 13:00 UTC | 6h 30m |
| 2026-05-18 | AFR6732 | CDG → ORD | May 18, 19:15 UTC | May 19, 03:25 UTC | 8h 10m |
| 2026-05-18 | AFR6741 | ORD → CDG | May 18, 07:15 UTC | May 18, 14:45 UTC | 7h 30m |
| 2026-05-17 | AFR6740 | CDG → ORD | May 17, 19:40 UTC | May 18, 04:11 UTC | 8h 30m |
| 2026-05-17 | AFR6727 | BOM → CDG | May 17, 06:50 UTC | May 17, 15:50 UTC | 9h 0m |
| 2026-05-16 | AFR6726 | CDG → BOM | May 16, 16:50 UTC | May 17, 01:20 UTC | 8h 30m |
| 2026-05-16 | AFR6723 | MEX → CDG | May 16, 04:15 UTC | May 16, 14:05 UTC | 9h 51m |
| 2026-05-15 | AFR6722 | CDG → MEX | May 15, 12:35 UTC | May 15, 23:45 UTC | 11h 9m |
| 2026-05-15 | AFR6729 | PEK → CDG | May 15, 04:55 UTC | May 15, 09:40 UTC | 4h 45m |
| 2026-05-14 | AFR6729 | PEK → CDG | May 14, 10:20 UTC | May 15, 09:40 UTC | 23h 20m |
| 2026-05-14 | AFR6729 | PEK → CDG | May 14, 08:20 UTC | May 15, 08:15 UTC | 23h 55m |
| 2026-05-14 | AFR6728 | CDG → PEK | May 14, 07:55 UTC | May 15, 06:05 UTC | 22h 10m |
| 2026-05-10 | AFR6727 | BOM → CDG | May 10, 00:30 UTC | May 10, 17:05 UTC | 16h 35m |
| 2026-05-09 | AFR6727 | BOM → CDG | May 9, 20:49 UTC | May 10, 17:05 UTC | 20h 15m |
| 2026-05-09 | AFR6727 | BOM → CDG | May 9, 18:20 UTC | May 10, 17:05 UTC | 22h 45m |
| 2026-05-09 | AFR6726 | CDG → BOM | May 9, 17:25 UTC | May 10, 16:14 UTC | 22h 50m |
| 2026-05-09 | AFR6723 | MEX → CDG | May 9, 04:15 UTC | May 9, 13:35 UTC | 9h 20m |
| 2026-05-09 | AFR6723 | MEX → CDG | May 9, 03:30 UTC | May 9, 03:40 UTC | 10m |
| 2026-05-08 | AFR6722 | CDG → MEX | May 8, 13:10 UTC | May 9, 00:35 UTC | 11h 25m |
| 2026-05-04 | AFR6721 | GDL → CDG | May 4, 13:10 UTC | May 5, 03:25 UTC | 14h 16m |
| 2026-05-03 | AFR6720 | CDG → MEX | May 3, 21:29 UTC | May 4, 08:25 UTC | 10h 55m |
| 2026-05-03 | AFR6727 | BOM → CDG | May 3, 10:10 UTC | May 3, 14:50 UTC | 4h 40m |
| 2026-05-03 | AFR6726 | CDG → BOM | May 3, 00:30 UTC | May 3, 00:50 UTC | 20m |
| 2026-05-02 | AFR6726 | CDG → BOM | May 2, 16:20 UTC | May 2, 23:45 UTC | 7h 25m |
| 2026-05-02 | AFR6723 | MEX → CDG | May 2, 03:40 UTC | May 2, 13:45 UTC | 10h 5m |
| 2026-05-01 | AFR6722 | CDG → MEX | May 1, 13:30 UTC | May 2, 00:45 UTC | 11h 15m |
| 2026-04-30 | AFR6729 | PEK → CDG | Apr 30, 21:40 UTC | May 1, 09:25 UTC | 11h 45m |
| 2026-04-30 | AFR6728 | CDG → PEK | Apr 30, 17:40 UTC | Apr 30, 18:00 UTC | 21m |
| 2026-04-30 | AFR6728 | CDG → PEK | Apr 30, 07:35 UTC | Apr 30, 11:50 UTC | 4h 15m |
| 2026-04-29 | AFR6739 | PIK → CDG | Apr 29, 07:55 UTC | Apr 29, 15:35 UTC | 7h 41m |
| 2026-04-28 | AFR6738 | CDG → ORD | Apr 28, 20:30 UTC | Apr 29, 04:39 UTC | 8h 10m |
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 .