sensors Mode-S transponder
ABC523
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N858AU · CESSNA 172 Skyhawk · operated by ALF IX LLC
- Hex
- ABC523
- Octal
- 52742443
- Decimal
- 11,257,123
- Country
- US
- Tail
- N858AU
- Type
- C172
- Flights observed
- 100
- Distinct callsigns
- 1
- Country
- US
- Last broadcast
- 1d ago
Current position
Country allocation
The ICAO 24-bit address ABC523 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 |
|---|---|---|---|
| N858AU | - | 100 | 2026-07-18 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-18 | N858AU | - | Jul 18, 20:25 UTC | Jul 18, 20:40 UTC | 15m |
| 2026-07-18 | N858AU | - | Jul 18, 12:35 UTC | Jul 18, 13:40 UTC | 1h 5m |
| 2026-07-13 | N858AU | DPA → DPA | Jul 13, 22:40 UTC | Jul 13, 22:50 UTC | 10m |
| 2026-07-13 | N858AU | - | Jul 13, 19:00 UTC | Jul 13, 21:25 UTC | 2h 25m |
| 2026-07-12 | N858AU | - | Jul 12, 20:20 UTC | Jul 12, 21:30 UTC | 1h 10m |
| 2026-07-12 | N858AU | - | Jul 12, 16:25 UTC | Jul 12, 17:45 UTC | 1h 20m |
| 2026-07-11 | N858AU | - | Jul 11, 23:15 UTC | Jul 11, 23:55 UTC | 40m |
| 2026-07-11 | N858AU | - | Jul 11, 17:00 UTC | Jul 11, 17:45 UTC | 45m |
| 2026-07-09 | N858AU | - | Jul 9, 16:50 UTC | Jul 9, 17:55 UTC | 1h 5m |
| 2026-07-07 | N858AU | - | Jul 7, 21:30 UTC | Jul 7, 22:35 UTC | 1h 5m |
| 2026-07-07 | N858AU | - | Jul 7, 18:20 UTC | Jul 7, 19:10 UTC | 50m |
| 2026-07-07 | N858AU | - | Jul 7, 17:10 UTC | Jul 7, 17:35 UTC | 25m |
| 2026-07-06 | N858AU | - | Jul 6, 23:15 UTC | Jul 7, 00:30 UTC | 1h 15m |
| 2026-07-06 | N858AU | - | Jul 6, 19:40 UTC | Jul 6, 21:00 UTC | 1h 20m |
| 2026-07-06 | N858AU | - | Jul 6, 14:20 UTC | Jul 6, 15:40 UTC | 1h 20m |
| 2026-07-02 | N858AU | - | Jul 2, 16:55 UTC | Jul 2, 17:50 UTC | 55m |
| 2026-06-29 | N858AU | - | Jun 29, 12:55 UTC | Jun 29, 14:09 UTC | 1h 15m |
| 2026-06-27 | N858AU | - | Jun 27, 17:09 UTC | Jun 27, 17:29 UTC | 20m |
| 2026-06-27 | N858AU | - | Jun 27, 15:14 UTC | Jun 27, 15:39 UTC | 25m |
| 2026-06-25 | N858AU | - | Jun 25, 20:54 UTC | Jun 25, 22:54 UTC | 2h 0m |
| 2026-06-25 | N858AU | - | Jun 25, 16:59 UTC | Jun 25, 17:39 UTC | 40m |
| 2026-06-25 | N858AU | - | Jun 25, 14:14 UTC | Jun 25, 15:20 UTC | 1h 5m |
| 2026-06-23 | N858AU | - | Jun 23, 20:10 UTC | Jun 23, 20:29 UTC | 20m |
| 2026-06-23 | N858AU | - | Jun 23, 18:25 UTC | Jun 23, 19:10 UTC | 45m |
| 2026-06-23 | N858AU | - | Jun 23, 15:44 UTC | Jun 23, 16:50 UTC | 1h 5m |
| 2026-06-22 | N858AU | - | Jun 22, 19:49 UTC | Jun 22, 21:14 UTC | 1h 25m |
| 2026-06-18 | N858AU | - | Jun 18, 23:00 UTC | Jun 19, 00:05 UTC | 1h 5m |
| 2026-06-18 | N858AU | - | Jun 18, 17:05 UTC | Jun 18, 17:45 UTC | 40m |
| 2026-06-16 | N858AU | - | Jun 16, 17:40 UTC | Jun 16, 18:25 UTC | 45m |
| 2026-06-15 | N858AU | - | Jun 15, 22:05 UTC | Jun 15, 22:45 UTC | 40m |
| 2026-06-15 | N858AU | - | Jun 15, 19:50 UTC | Jun 15, 20:54 UTC | 1h 5m |
| 2026-06-10 | N858AU | - | Jun 10, 16:35 UTC | Jun 10, 17:30 UTC | 55m |
| 2026-06-10 | N858AU | DPA → DPA | Jun 10, 01:40 UTC | Jun 10, 03:05 UTC | 1h 25m |
| 2026-06-07 | N858AU | - | Jun 7, 17:15 UTC | Jun 7, 17:50 UTC | 35m |
| 2026-06-03 | N858AU | - | Jun 3, 22:50 UTC | Jun 3, 23:55 UTC | 1h 5m |
| 2026-06-03 | N858AU | - | Jun 3, 19:30 UTC | Jun 3, 20:55 UTC | 1h 25m |
| 2026-06-02 | N858AU | - | Jun 2, 17:45 UTC | Jun 2, 18:55 UTC | 1h 10m |
| 2026-06-02 | N858AU | - | Jun 2, 15:45 UTC | Jun 2, 16:40 UTC | 55m |
| 2026-06-01 | N858AU | - | Jun 1, 18:55 UTC | Jun 1, 20:00 UTC | 1h 5m |
| 2026-06-01 | N858AU | - | Jun 1, 16:40 UTC | Jun 1, 17:50 UTC | 1h 10m |
| 2026-05-31 | N858AU | - | May 31, 19:50 UTC | May 31, 20:25 UTC | 35m |
| 2026-05-31 | N858AU | - | May 31, 18:25 UTC | May 31, 18:55 UTC | 30m |
| 2026-05-31 | N858AU | - | May 31, 17:05 UTC | May 31, 17:55 UTC | 50m |
| 2026-05-29 | N858AU | - | May 29, 17:35 UTC | May 29, 18:50 UTC | 1h 15m |
| 2026-05-29 | N858AU | - | May 29, 16:00 UTC | May 29, 16:15 UTC | 15m |
| 2026-05-28 | N858AU | - | May 28, 22:10 UTC | May 28, 22:45 UTC | 35m |
| 2026-05-27 | N858AU | - | May 27, 21:45 UTC | May 27, 22:55 UTC | 1h 10m |
| 2026-05-27 | N858AU | - | May 27, 19:20 UTC | May 27, 19:55 UTC | 35m |
| 2026-05-27 | N858AU | - | May 27, 14:10 UTC | May 27, 15:55 UTC | 1h 45m |
| 2026-05-26 | N858AU | - | May 26, 22:05 UTC | May 26, 22:29 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 N858AU page for operator, model, and routing details .