sensors Mode-S transponder
A5EF01
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N4812U · CESSNA 201 Centurion · operated by FOSTER FRANK BRIAN
- Hex
- A5EF01
- Octal
- 51367401
- Decimal
- 10,874,625
- Country
- US
- Tail
- N4812U
- Type
- C210
- Flights observed
- 45
- Distinct callsigns
- 1
- Country
- US
- Last broadcast
- 10h ago
Last known position
Country allocation
The ICAO 24-bit address A5EF01 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States 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 |
|---|---|---|---|
| N4812U | - | 45 | 2026-06-25 |
Recent flights last 45
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-06-25 | N4812U | - | Jun 25, 22:49 UTC | Jun 25, 23:09 UTC | 20m |
| 2026-06-25 | N4812U | - | Jun 25, 18:10 UTC | Jun 25, 20:30 UTC | 2h 20m |
| 2026-06-23 | N4812U | - | Jun 23, 15:34 UTC | Jun 23, 16:20 UTC | 45m |
| 2026-06-21 | N4812U | - | Jun 21, 16:19 UTC | Jun 21, 17:45 UTC | 1h 25m |
| 2026-06-20 | N4812U | - | Jun 20, 21:14 UTC | Jun 20, 22:10 UTC | 55m |
| 2026-06-17 | N4812U | - | Jun 17, 09:55 UTC | Jun 17, 10:15 UTC | 20m |
| 2026-06-17 | N4812U | - | Jun 17, 00:35 UTC | Jun 17, 00:50 UTC | 15m |
| 2026-06-16 | N4812U | - | Jun 16, 22:35 UTC | Jun 16, 23:05 UTC | 30m |
| 2026-06-16 | N4812U | - | Jun 16, 12:55 UTC | Jun 16, 13:04 UTC | 10m |
| 2026-06-10 | N4812U | - | Jun 10, 10:35 UTC | Jun 10, 11:25 UTC | 50m |
| 2026-06-09 | N4812U | - | Jun 9, 19:00 UTC | Jun 9, 19:30 UTC | 30m |
| 2026-06-08 | N4812U | - | Jun 8, 20:00 UTC | Jun 8, 20:40 UTC | 40m |
| 2026-06-06 | N4812U | - | Jun 6, 15:59 UTC | Jun 6, 17:10 UTC | 1h 10m |
| 2026-06-05 | N4812U | - | Jun 5, 16:35 UTC | Jun 5, 17:10 UTC | 35m |
| 2026-06-05 | N4812U | - | Jun 5, 14:10 UTC | Jun 5, 15:25 UTC | 1h 15m |
| 2026-06-03 | N4812U | - | Jun 3, 21:15 UTC | Jun 3, 23:00 UTC | 1h 45m |
| 2026-06-02 | N4812U | - | Jun 2, 15:30 UTC | Jun 2, 17:05 UTC | 1h 35m |
| 2026-05-31 | N4812U | - | May 31, 23:50 UTC | Jun 1, 00:00 UTC | 10m |
| 2026-05-27 | N4812U | - | May 27, 17:40 UTC | May 27, 19:15 UTC | 1h 35m |
| 2026-05-21 | N4812U | - | May 21, 21:15 UTC | May 21, 21:30 UTC | 15m |
| 2026-05-19 | N4812U | - | May 19, 23:55 UTC | May 20, 00:20 UTC | 25m |
| 2026-05-18 | N4812U | - | May 18, 22:10 UTC | May 18, 22:20 UTC | 10m |
| 2026-05-14 | N4812U | - | May 14, 21:25 UTC | May 14, 23:50 UTC | 2h 25m |
| 2026-05-14 | N4812U | - | May 14, 20:30 UTC | May 14, 20:50 UTC | 20m |
| 2026-05-13 | N4812U | - | May 13, 17:10 UTC | May 13, 18:05 UTC | 55m |
| 2026-05-13 | N4812U | - | May 13, 15:00 UTC | May 13, 16:20 UTC | 1h 20m |
| 2026-05-13 | N4812U | - | May 13, 13:31 UTC | May 13, 14:30 UTC | 1h 0m |
| 2026-05-08 | N4812U | - | May 8, 17:55 UTC | May 8, 18:25 UTC | 30m |
| 2026-05-08 | N4812U | - | May 8, 16:30 UTC | May 8, 16:50 UTC | 20m |
| 2026-05-08 | N4812U | - | May 8, 15:15 UTC | May 8, 15:55 UTC | 40m |
| 2026-04-25 | N4812U | - | Apr 25, 17:15 UTC | Apr 25, 17:45 UTC | 30m |
| 2026-04-25 | N4812U | - | Apr 25, 14:45 UTC | Apr 25, 16:35 UTC | 1h 50m |
| 2026-04-25 | N4812U | - | Apr 25, 13:40 UTC | Apr 25, 14:00 UTC | 20m |
| 2026-04-24 | N4812U | - | Apr 24, 21:50 UTC | Apr 24, 22:40 UTC | 50m |
| 2026-04-24 | N4812U | - | Apr 24, 19:15 UTC | Apr 24, 20:55 UTC | 1h 40m |
| 2026-04-23 | N4812U | - | Apr 23, 14:20 UTC | Apr 23, 14:40 UTC | 20m |
| 2026-04-22 | N4812U | - | Apr 22, 20:30 UTC | Apr 22, 20:40 UTC | 10m |
| 2026-04-22 | N4812U | - | Apr 22, 18:45 UTC | Apr 22, 19:55 UTC | 1h 10m |
| 2026-04-22 | N4812U | - | Apr 22, 16:00 UTC | Apr 22, 17:50 UTC | 1h 50m |
| 2026-04-19 | N4812U | - | Apr 19, 15:45 UTC | Apr 19, 16:10 UTC | 25m |
| 2026-04-16 | N4812U | - | Apr 16, 13:20 UTC | Apr 16, 14:25 UTC | 1h 5m |
| 2026-04-16 | N4812U | - | Apr 16, 11:44 UTC | Apr 16, 13:05 UTC | 1h 20m |
| 2026-04-15 | N4812U | - | Apr 15, 22:05 UTC | Apr 15, 22:40 UTC | 35m |
| 2026-04-15 | N4812U | - | Apr 15, 21:05 UTC | Apr 15, 21:35 UTC | 30m |
| 2026-04-15 | N4812U | - | Apr 15, 20:50 UTC | Apr 15, 21:00 UTC | 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 N4812U page for operator, model, and routing details .