sensors Mode-S transponder
447D21
ICAO 24-bit transponder address · allocated to Austria
Currently assigned to 6M-BA · SIKORSKY UH-60 Black Hawk
- Hex
- 447D21
- Octal
- 21076441
- Decimal
- 4,488,481
- Country
- AT
- Tail
- 6M-BA
- Type
- H60
- Flights observed
- 34
- Distinct callsigns
- 1
- Country
- AT
- Last broadcast
- 24m ago
Current position
Country allocation
The ICAO 24-bit address 447D21 falls within the block assigned to Austria (AT) by ICAO Annex 10, Volume III. Every aircraft registered in Austria 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 |
|---|---|---|---|
| BLACK71 | - | 33 | 2026-06-02 |
Recent flights last 34
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-06-02 | BLACK71 | - | Jun 2, 19:35 UTC | Jun 2, 20:15 UTC | 40m |
| 2026-06-02 | BLACK71 | - | Jun 2, 13:15 UTC | Jun 2, 15:00 UTC | 1h 45m |
| 2026-06-02 | BLACK71 | - | Jun 2, 11:05 UTC | Jun 2, 11:20 UTC | 15m |
| 2026-05-30 | BLACK71 | - | May 30, 12:40 UTC | May 30, 12:55 UTC | 15m |
| 2026-05-30 | BLACK71 | - | May 30, 06:20 UTC | May 30, 06:40 UTC | 20m |
| 2026-05-29 | BLACK71 | - | May 29, 07:35 UTC | May 29, 09:30 UTC | 1h 55m |
| 2026-05-27 | BLACK71 | - | May 27, 10:30 UTC | May 27, 11:20 UTC | 50m |
| 2026-05-27 | BLACK71 | - | May 27, 07:15 UTC | May 27, 08:40 UTC | 1h 25m |
| 2026-05-22 | BLACK71 | - | May 22, 06:05 UTC | May 22, 08:30 UTC | 2h 25m |
| 2026-05-21 | BLACK71 | - | May 21, 10:35 UTC | May 21, 11:00 UTC | 25m |
| 2026-05-21 | BLACK71 | - | May 21, 07:10 UTC | May 21, 08:35 UTC | 1h 25m |
| 2026-05-20 | BLACK71 | - | May 20, 11:10 UTC | May 20, 11:30 UTC | 20m |
| 2026-05-20 | BLACK71 | - | May 20, 08:45 UTC | May 20, 09:55 UTC | 1h 10m |
| 2026-05-20 | BLACK71 | - | May 20, 07:45 UTC | May 20, 08:10 UTC | 25m |
| 2026-05-19 | BLACK71 | - | May 19, 06:45 UTC | May 19, 07:00 UTC | 15m |
| 2026-05-13 | BLACK71 | - | May 13, 07:55 UTC | May 13, 08:10 UTC | 15m |
| 2026-05-12 | BLACK71 | - | May 12, 20:25 UTC | May 12, 20:50 UTC | 25m |
| 2026-05-12 | BLACK71 | - | May 12, 17:35 UTC | May 12, 17:55 UTC | 20m |
| 2026-05-12 | BLACK71 | - | May 12, 09:55 UTC | May 12, 10:15 UTC | 20m |
| 2026-05-11 | BLACK71 | - | May 11, 14:30 UTC | May 11, 14:45 UTC | 15m |
| 2026-05-11 | BLACK71 | - | May 11, 10:50 UTC | May 11, 11:10 UTC | 20m |
| 2026-05-08 | BLACK71 | - | May 8, 09:14 UTC | May 8, 09:25 UTC | 10m |
| 2026-05-07 | BLACK71 | - | May 7, 19:00 UTC | May 7, 20:25 UTC | 1h 25m |
| 2026-05-07 | BLACK71 | - | May 7, 14:05 UTC | May 7, 15:55 UTC | 1h 50m |
| 2026-05-06 | BLACK71 | - | May 6, 11:45 UTC | May 6, 11:55 UTC | 10m |
| 2026-04-23 | BLACK71 | - | Apr 23, 13:55 UTC | Apr 23, 14:50 UTC | 55m |
| 2026-04-20 | BLACK71 | - | Apr 20, 07:15 UTC | Apr 20, 07:30 UTC | 15m |
| 2026-04-16 | BLACK71 | - | Apr 16, 19:55 UTC | Apr 16, 20:25 UTC | 30m |
| 2026-04-16 | BLACK71 | - | Apr 16, 18:35 UTC | Apr 16, 18:55 UTC | 20m |
| 2026-04-15 | BLACK71 | - | Apr 15, 09:00 UTC | Apr 15, 09:10 UTC | 10m |
| 2026-04-15 | BLACK71 | - | Apr 15, 07:35 UTC | Apr 15, 08:55 UTC | 1h 20m |
| 2026-04-14 | BLACK71 | - | Apr 14, 20:05 UTC | Apr 14, 20:30 UTC | 25m |
| 2026-04-14 | BLACK71 | - | Apr 14, 12:50 UTC | Apr 14, 14:05 UTC | 1h 15m |
| 2026-04-14 | BLACK71 | - | Apr 14, 12:10 UTC | Apr 14, 12:45 UTC | 35m |
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 6M-BA page for operator, model, and routing details .