sensors Mode-S transponder
781DC7
ICAO 24-bit transponder address · allocated to China
Currently assigned to B-221Y · BOEING 777-200LR
- Hex
- 781DC7
- Octal
- 36016707
- Decimal
- 7,871,943
- Country
- CN
- Tail
- B-221Y
- Type
- B77L
- Flights observed
- 83
- Distinct callsigns
- 7
- Country
- CN
- Last broadcast
- 2h ago
Last known position
Country allocation
The ICAO 24-bit address 781DC7 falls within the block assigned to China (CN) by ICAO Annex 10, Volume III. Every aircraft registered in China 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 7 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| CYZ257 | - | 31 | 2026-05-30 |
| CYZ256 | China Postal Airlines | 17 | 2026-05-13 |
| CYZ255 | China Postal Airlines | 17 | 2026-05-14 |
| CYZ258 | - | 11 | 2026-05-28 |
| CYZ294 | - | 3 | 2026-05-27 |
| CYZ278 | - | 2 | 2026-05-23 |
| CYZ237 | - | 2 | 2026-05-26 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-30 | CYZ257 | - | May 30, 06:30 UTC | May 30, 07:00 UTC | 30m |
| 2026-05-30 | CYZ257 | - | May 30, 00:40 UTC | May 30, 04:00 UTC | 3h 20m |
| 2026-05-28 | CYZ258 | - | May 28, 11:20 UTC | May 28, 17:55 UTC | 6h 35m |
| 2026-05-27 | CYZ257 | - | May 27, 11:50 UTC | May 28, 06:55 UTC | 19h 5m |
| 2026-05-27 | CYZ257 | - | May 27, 11:10 UTC | May 28, 06:55 UTC | 19h 45m |
| 2026-05-27 | CYZ257 | - | May 27, 07:50 UTC | May 28, 06:55 UTC | 23h 5m |
| 2026-05-27 | CYZ294 | - | May 27, 05:49 UTC | May 28, 05:45 UTC | 23h 55m |
| 2026-05-26 | CYZ237 | - | May 26, 02:55 UTC | May 26, 09:35 UTC | 6h 40m |
| 2026-05-23 | CYZ278 | - | May 23, 10:45 UTC | May 23, 16:50 UTC | 6h 5m |
| 2026-05-23 | CYZ257 | - | May 23, 01:05 UTC | May 23, 07:40 UTC | 6h 35m |
| 2026-05-21 | CYZ258 | - | May 21, 10:55 UTC | May 21, 17:10 UTC | 6h 15m |
| 2026-05-21 | CYZ257 | - | May 21, 00:40 UTC | May 21, 07:00 UTC | 6h 20m |
| 2026-05-20 | CYZ257 | - | May 20, 10:55 UTC | May 21, 07:00 UTC | 20h 5m |
| 2026-05-20 | CYZ257 | - | May 20, 07:50 UTC | May 21, 07:00 UTC | 23h 10m |
| 2026-05-20 | CYZ294 | - | May 20, 05:50 UTC | May 21, 03:55 UTC | 22h 5m |
| 2026-05-20 | CYZ294 | - | May 20, 05:35 UTC | May 21, 03:45 UTC | 22h 10m |
| 2026-05-19 | CYZ237 | - | May 19, 03:20 UTC | May 19, 10:05 UTC | 6h 45m |
| 2026-05-16 | CYZ278 | - | May 16, 14:05 UTC | May 16, 20:15 UTC | 6h 10m |
| 2026-05-15 | CYZ257 | - | May 15, 15:50 UTC | May 16, 10:01 UTC | 18h 11m |
| 2026-05-15 | CYZ257 | - | May 15, 15:10 UTC | May 16, 10:01 UTC | 18h 51m |
| 2026-05-15 | CYZ257 | - | May 15, 11:50 UTC | May 16, 10:01 UTC | 22h 10m |
| 2026-05-15 | CYZ258 | - | May 15, 09:50 UTC | May 16, 09:45 UTC | 23h 55m |
| 2026-05-15 | CYZ258 | - | May 15, 09:40 UTC | May 16, 07:01 UTC | 21h 20m |
| 2026-05-14 | CYZ255 | NKG → LUX | May 14, 23:30 UTC | May 15, 05:45 UTC | 6h 15m |
| 2026-05-13 | CYZ256 | LUX → NKG | May 13, 09:50 UTC | May 13, 16:00 UTC | 6h 10m |
| 2026-05-12 | CYZ255 | NKG → LUX | May 12, 23:10 UTC | May 13, 05:50 UTC | 6h 40m |
| 2026-05-11 | CYZ256 | LUX → NKG | May 11, 12:55 UTC | May 11, 18:50 UTC | 5h 56m |
| 2026-05-11 | CYZ257 | - | May 11, 01:34 UTC | May 11, 09:55 UTC | 8h 20m |
| 2026-05-10 | CYZ257 | - | May 10, 14:09 UTC | May 11, 09:55 UTC | 19h 45m |
| 2026-05-10 | CYZ257 | - | May 10, 12:05 UTC | May 11, 09:55 UTC | 21h 50m |
| 2026-05-10 | CYZ257 | - | May 10, 09:50 UTC | May 11, 09:45 UTC | 23h 55m |
| 2026-05-10 | CYZ258 | - | May 10, 08:54 UTC | May 11, 06:40 UTC | 21h 45m |
| 2026-05-09 | CYZ257 | - | May 9, 21:25 UTC | May 10, 05:34 UTC | 8h 10m |
| 2026-05-08 | CYZ258 | - | May 8, 09:30 UTC | May 8, 15:20 UTC | 5h 50m |
| 2026-05-07 | CYZ255 | NKG → LUX | May 7, 22:00 UTC | May 8, 06:30 UTC | 8h 30m |
| 2026-05-04 | CYZ256 | LUX → NKG | May 4, 13:00 UTC | May 4, 18:45 UTC | 5h 46m |
| 2026-05-04 | CYZ257 | - | May 4, 01:35 UTC | May 4, 10:05 UTC | 8h 30m |
| 2026-05-03 | CYZ257 | - | May 3, 14:00 UTC | May 4, 10:05 UTC | 20h 5m |
| 2026-05-03 | CYZ257 | - | May 3, 12:00 UTC | May 4, 10:05 UTC | 22h 5m |
| 2026-05-03 | CYZ258 | - | May 3, 09:50 UTC | May 4, 09:45 UTC | 23h 55m |
| 2026-05-03 | CYZ258 | - | May 3, 08:50 UTC | May 4, 06:40 UTC | 21h 50m |
| 2026-05-02 | CYZ257 | - | May 2, 21:25 UTC | May 3, 05:50 UTC | 8h 24m |
| 2026-05-01 | CYZ258 | - | May 1, 10:15 UTC | May 1, 16:35 UTC | 6h 20m |
| 2026-04-30 | CYZ255 | NKG → LUX | Apr 30, 22:15 UTC | May 1, 06:15 UTC | 8h 0m |
| 2026-04-29 | CYZ256 | LUX → NKG | Apr 29, 09:55 UTC | Apr 29, 16:20 UTC | 6h 25m |
| 2026-04-28 | CYZ255 | NKG → LUX | Apr 28, 21:50 UTC | Apr 29, 05:35 UTC | 7h 45m |
| 2026-04-27 | CYZ256 | LUX → NKG | Apr 27, 12:50 UTC | Apr 27, 16:25 UTC | 3h 35m |
| 2026-04-26 | CYZ257 | - | Apr 26, 15:15 UTC | Apr 27, 09:35 UTC | 18h 20m |
| 2026-04-26 | CYZ257 | - | Apr 26, 11:50 UTC | Apr 27, 09:35 UTC | 21h 45m |
| 2026-04-26 | CYZ258 | LUX → LUX | Apr 26, 09:50 UTC | Apr 27, 09:35 UTC | 23h 45m |
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 B-221Y page for operator, model, and routing details .