sensors Mode-S transponder
781B8A
ICAO 24-bit transponder address · allocated to China
Currently assigned to B-129Y · CESSNA 560XL Citation XLS
- Hex
- 781B8A
- Octal
- 36015612
- Decimal
- 7,871,370
- Country
- CN
- Tail
- B-129Y
- Type
- C56X
- Flights observed
- 5
- Distinct callsigns
- 3
- Country
- CN
- Last broadcast
- 34m ago
Last known position
Country allocation
The ICAO 24-bit address 781B8A 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 3 distinct
Recent flights last 5
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-24 | CFI131 | - | Jul 24, 21:10 UTC | Jul 25, 00:15 UTC | 3h 5m |
| 2026-07-23 | CFI131 | - | Jul 23, 21:00 UTC | Jul 24, 00:05 UTC | 3h 5m |
| 2026-07-22 | CFI131 | - | Jul 22, 21:05 UTC | Jul 23, 00:10 UTC | 3h 5m |
| 2026-07-10 | CFI029 | - | Jul 10, 03:55 UTC | Jul 10, 04:10 UTC | 15m |
| 2026-06-01 | CFI043 | - | Jun 1, 02:05 UTC | Jun 1, 02:30 UTC | 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 B-129Y page for operator, model, and routing details .