sensors Mode-S transponder
7C2521
ICAO 24-bit transponder address · allocated to Australia
Currently assigned to VH-HMB · PIPER PA-44 Seminole · operated by MELBOURNE FLIGHT ACADEMY PTY LTD
- Hex
- 7C2521
- Octal
- 37022441
- Decimal
- 8,135,969
- Country
- AU
- Tail
- VH-HMB
- Type
- PA44
- Flights observed
- 27
- Distinct callsigns
- 1
- Country
- AU
- Last broadcast
- 1d ago
Last known position
Country allocation
The ICAO 24-bit address 7C2521 falls within the block assigned to Australia (AU) by ICAO Annex 10, Volume III. Every aircraft registered in Australia 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 |
|---|---|---|---|
| HMB | - | 27 | 2026-05-29 |
Recent flights last 27
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | HMB | - | May 29, 05:15 UTC | May 29, 06:10 UTC | 55m |
| 2026-05-29 | HMB | - | May 29, 03:00 UTC | May 29, 03:25 UTC | 25m |
| 2026-05-29 | HMB | - | May 29, 01:35 UTC | May 29, 02:00 UTC | 25m |
| 2026-05-22 | HMB | MEB → MEB | May 22, 05:30 UTC | May 22, 06:20 UTC | 50m |
| 2026-05-21 | HMB | - | May 21, 00:40 UTC | May 21, 00:55 UTC | 15m |
| 2026-05-06 | HMB | MEB → MBW | May 6, 02:01 UTC | May 6, 03:15 UTC | 1h 14m |
| 2026-04-30 | HMB | - | Apr 30, 02:00 UTC | Apr 30, 05:05 UTC | 3h 5m |
| 2026-04-28 | HMB | - | Apr 28, 03:45 UTC | Apr 28, 04:55 UTC | 1h 10m |
| 2026-04-28 | HMB | - | Apr 28, 02:15 UTC | Apr 28, 03:15 UTC | 1h 0m |
| 2026-04-25 | HMB | MEB → MEB | Apr 25, 05:30 UTC | Apr 25, 06:15 UTC | 45m |
| 2026-04-23 | HMB | MEB → MEB | Apr 23, 06:20 UTC | Apr 23, 07:15 UTC | 55m |
| 2026-04-23 | HMB | - | Apr 23, 00:25 UTC | Apr 23, 02:00 UTC | 1h 35m |
| 2026-04-22 | HMB | - | Apr 22, 02:05 UTC | Apr 22, 05:01 UTC | 2h 55m |
| 2026-04-21 | HMB | - | Apr 21, 02:50 UTC | Apr 21, 03:25 UTC | 35m |
| 2026-04-21 | HMB | - | Apr 21, 00:40 UTC | Apr 21, 01:15 UTC | 35m |
| 2026-04-20 | HMB | MEB → MEB | Apr 20, 04:30 UTC | Apr 20, 04:55 UTC | 25m |
| 2026-04-20 | HMB | - | Apr 20, 00:30 UTC | Apr 20, 02:05 UTC | 1h 35m |
| 2026-04-19 | HMB | - | Apr 19, 23:00 UTC | Apr 20, 00:00 UTC | 1h 0m |
| 2026-04-19 | HMB | MEB → MEB | Apr 19, 01:30 UTC | Apr 19, 04:35 UTC | 3h 5m |
| 2026-04-17 | HMB | MEB → MEB | Apr 17, 06:15 UTC | Apr 17, 07:15 UTC | 1h 0m |
| 2026-04-17 | HMB | - | Apr 17, 02:25 UTC | Apr 17, 02:50 UTC | 25m |
| 2026-04-17 | HMB | - | Apr 17, 01:25 UTC | Apr 17, 01:45 UTC | 20m |
| 2026-04-17 | HMB | - | Apr 17, 00:25 UTC | Apr 17, 01:04 UTC | 40m |
| 2026-04-15 | HMB | - | Apr 15, 02:10 UTC | Apr 15, 02:25 UTC | 15m |
| 2026-04-15 | HMB | - | Apr 15, 00:30 UTC | Apr 15, 00:50 UTC | 20m |
| 2026-04-13 | HMB | - | Apr 13, 00:20 UTC | Apr 13, 00:30 UTC | 10m |
| 2026-04-12 | HMB | MBW → MEB | Apr 12, 23:55 UTC | Apr 13, 00:30 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 VH-HMB page for operator, model, and routing details .