sensors Mode-S transponder
A631D1
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N499CZ · BEECH 99 Airliner · operated by N499CZ LLC
- Hex
- A631D1
- Octal
- 51430721
- Decimal
- 10,891,729
- Country
- US
- Tail
- N499CZ
- Type
- BE99
- Flights observed
- 58
- Distinct callsigns
- 11
- Country
- US
- Last broadcast
- 1d ago
Last known position
Country allocation
The ICAO 24-bit address A631D1 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 11 distinct
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-17 | FRG986 | MEM → LRD | Jul 17, 04:10 UTC | Jul 17, 07:44 UTC | 3h 35m |
| 2026-07-17 | FRG986 | - | Jul 17, 00:25 UTC | Jul 17, 03:20 UTC | 2h 55m |
| 2026-07-16 | FRG986 | - | Jul 16, 20:55 UTC | Jul 16, 22:15 UTC | 1h 20m |
| 2026-06-19 | FRG1549 | - | Jun 19, 00:49 UTC | Jun 19, 01:34 UTC | 45m |
| 2026-06-18 | FRG1550 | - | Jun 18, 14:40 UTC | Jun 18, 15:35 UTC | 55m |
| 2026-06-18 | FRG1509 | - | Jun 18, 00:50 UTC | Jun 18, 01:40 UTC | 50m |
| 2026-06-17 | FRG1510 | - | Jun 17, 11:25 UTC | Jun 17, 12:10 UTC | 45m |
| 2026-06-17 | FRG1509 | - | Jun 17, 00:45 UTC | Jun 17, 01:25 UTC | 40m |
| 2026-06-16 | FRG1510 | - | Jun 16, 11:45 UTC | Jun 16, 12:30 UTC | 45m |
| 2026-06-16 | FRG1509 | - | Jun 16, 01:15 UTC | Jun 16, 01:45 UTC | 30m |
| 2026-06-12 | FRG1510 | - | Jun 12, 12:30 UTC | Jun 12, 13:15 UTC | 45m |
| 2026-06-11 | FRG1510 | - | Jun 11, 11:45 UTC | Jun 11, 12:30 UTC | 45m |
| 2026-06-10 | FRG1510 | - | Jun 10, 11:30 UTC | Jun 10, 12:10 UTC | 40m |
| 2026-06-10 | FRG9499 | - | Jun 10, 06:25 UTC | Jun 10, 06:45 UTC | 20m |
| 2026-06-09 | FRG1510 | - | Jun 9, 11:45 UTC | Jun 9, 12:25 UTC | 40m |
| 2026-06-09 | FRG1509 | - | Jun 9, 00:50 UTC | Jun 9, 01:35 UTC | 45m |
| 2026-06-06 | FRG1544 | - | Jun 6, 12:30 UTC | Jun 6, 13:15 UTC | 45m |
| 2026-06-06 | FRG1543 | - | Jun 6, 00:55 UTC | Jun 6, 01:40 UTC | 45m |
| 2026-06-05 | FRG1544 | - | Jun 5, 11:40 UTC | Jun 5, 12:25 UTC | 45m |
| 2026-06-05 | FRG1509 | - | Jun 5, 00:40 UTC | Jun 5, 01:25 UTC | 45m |
| 2026-06-04 | FRG1510 | - | Jun 4, 11:30 UTC | Jun 4, 12:10 UTC | 40m |
| 2026-06-04 | FRG1509 | - | Jun 4, 00:40 UTC | Jun 4, 01:25 UTC | 45m |
| 2026-06-03 | FRG1510 | - | Jun 3, 11:30 UTC | Jun 3, 12:10 UTC | 40m |
| 2026-06-03 | FRG1509 | - | Jun 3, 00:35 UTC | Jun 3, 01:20 UTC | 45m |
| 2026-06-02 | FRG1510 | - | Jun 2, 11:30 UTC | Jun 2, 12:10 UTC | 40m |
| 2026-06-02 | FRG1509 | - | Jun 2, 01:00 UTC | Jun 2, 01:40 UTC | 40m |
| 2026-05-29 | FRG1510 | - | May 29, 11:35 UTC | May 29, 12:10 UTC | 35m |
| 2026-05-29 | FRG1509 | - | May 29, 01:10 UTC | May 29, 01:35 UTC | 25m |
| 2026-05-28 | FRG1510 | - | May 28, 11:45 UTC | May 28, 12:30 UTC | 45m |
| 2026-05-27 | FRG1510 | - | May 27, 11:50 UTC | May 27, 12:30 UTC | 40m |
| 2026-05-27 | FRG1509 | - | May 27, 00:30 UTC | May 27, 01:14 UTC | 45m |
| 2026-05-23 | FRG1544 | MKE → CWA | May 23, 14:00 UTC | May 23, 14:45 UTC | 45m |
| 2026-05-21 | FRG9499 | - | May 21, 03:45 UTC | May 21, 04:45 UTC | 1h 0m |
| 2026-05-21 | FRG9499 | - | May 21, 02:15 UTC | May 21, 03:10 UTC | 55m |
| 2026-05-20 | FRG877 | - | May 20, 22:10 UTC | May 21, 01:00 UTC | 2h 50m |
| 2026-05-20 | FRG9499 | - | May 20, 11:10 UTC | May 20, 14:05 UTC | 2h 55m |
| 2026-05-20 | FRG872 | - | May 20, 06:45 UTC | May 20, 09:30 UTC | 2h 45m |
| 2026-05-20 | FRG872 | - | May 20, 04:45 UTC | May 20, 05:05 UTC | 20m |
| 2026-05-16 | FRG1549 | - | May 16, 00:40 UTC | May 16, 01:25 UTC | 45m |
| 2026-05-15 | FRG1550 | - | May 15, 11:40 UTC | May 15, 12:25 UTC | 45m |
| 2026-05-15 | FRG1509 | - | May 15, 01:05 UTC | May 15, 01:40 UTC | 35m |
| 2026-05-14 | FRG1510 | - | May 14, 11:40 UTC | May 14, 12:20 UTC | 40m |
| 2026-05-13 | FRG1544 | - | May 13, 11:55 UTC | May 13, 12:40 UTC | 45m |
| 2026-05-13 | FRG1509 | - | May 13, 00:50 UTC | May 13, 01:25 UTC | 35m |
| 2026-05-12 | FRG1510 | - | May 12, 11:50 UTC | May 12, 12:30 UTC | 40m |
| 2026-05-09 | FRG1544 | - | May 9, 12:40 UTC | May 9, 13:25 UTC | 45m |
| 2026-05-08 | FRG1544 | - | May 8, 12:00 UTC | May 8, 12:44 UTC | 45m |
| 2026-05-07 | FRG1510 | - | May 7, 11:30 UTC | May 7, 12:15 UTC | 45m |
| 2026-05-06 | FRG1544 | - | May 6, 12:35 UTC | May 6, 13:15 UTC | 40m |
| 2026-05-01 | FRG1550 | - | May 1, 11:55 UTC | May 1, 12:40 UTC | 45m |
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 N499CZ page for operator, model, and routing details .