sensors Mode-S transponder
A54535
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N439GT · operated by ATLAS AIR INC
- Hex
- A54535
- Octal
- 51242465
- Decimal
- 10,831,157
- Country
- US
- Tail
- N439GT
- Type
- B744
- Flights observed
- 210
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- Jul 26, 20:45 UTC
Last known position
Country allocation
The ICAO 24-bit address A54535 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 20 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| GTI8174 | - | 28 | 2026-06-27 |
| GTI8173 | - | 15 | 2026-06-25 |
| GTI518 | - | 15 | 2026-07-09 |
| GTI812 | - | 11 | 2026-07-17 |
| GTI517 | - | 11 | 2026-07-07 |
| GTI8603 | Atlas Air | 8 | 2026-07-23 |
| GTI365 | Atlas Air | 7 | 2026-06-13 |
| GTI8439 | Atlas Air | 6 | 2026-04-17 |
| GTI8602 | Atlas Air | 5 | 2026-07-22 |
| GTI8577 | - | 5 | 2026-07-04 |
| GTI8193 | Atlas Air | 5 | 2026-05-21 |
| GTI364 | Atlas Air | 5 | 2026-06-12 |
| GTI8523 | Atlas Air | 4 | 2026-06-01 |
| GTI8275 | Atlas Air | 4 | 2026-06-20 |
| GTI8002 | Atlas Air | 4 | 2026-04-28 |
| GTI8948 | - | 3 | 2026-06-18 |
| GTI8679 | - | 3 | 2026-06-06 |
| GTI8554 | Atlas Air | 3 | 2026-05-18 |
| GTI8318 | Atlas Air | 3 | 2026-04-30 |
| GTI8296 | Atlas Air | 3 | 2026-06-28 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | GTI8836 | PSM → HHN | Jul 26, 13:30 UTC | Jul 26, 20:45 UTC | 7h 15m |
| 2026-07-26 | GTI6091 | LGG → ORD | Jul 26, 02:20 UTC | Jul 26, 10:30 UTC | 8h 11m |
| 2026-07-25 | THY6091 | IST → LGG | Jul 25, 21:05 UTC | Jul 25, 23:40 UTC | 2h 35m |
| 2026-07-24 | THY6045 | IST → MIA | Jul 24, 05:35 UTC | Jul 24, 15:45 UTC | 10h 10m |
| 2026-07-24 | THY6044 | IST → LGG | Jul 24, 00:00 UTC | Jul 24, 01:40 UTC | 1h 40m |
| 2026-07-23 | GTI8603 | MIA → MST | Jul 23, 10:30 UTC | Jul 23, 16:35 UTC | 6h 5m |
| 2026-07-22 | GTI8603 | MIA → MST | Jul 22, 13:20 UTC | Jul 23, 08:55 UTC | 19h 35m |
| 2026-07-22 | GTI8602 | ORD → ICN | Jul 22, 11:30 UTC | Jul 23, 08:55 UTC | 21h 25m |
| 2026-07-22 | GTI8602 | ORD → ICN | Jul 22, 02:40 UTC | Jul 22, 04:00 UTC | 1h 20m |
| 2026-07-21 | GTI8603 | ANC → JFK | Jul 21, 10:15 UTC | Jul 21, 16:45 UTC | 6h 30m |
| 2026-07-20 | GTI8603 | - | Jul 20, 17:10 UTC | Jul 21, 08:30 UTC | 15h 20m |
| 2026-07-20 | GTI8602 | ORD → ICN | Jul 20, 11:05 UTC | Jul 21, 08:30 UTC | 21h 24m |
| 2026-07-20 | GTI8602 | ORD → ICN | Jul 20, 01:50 UTC | Jul 20, 08:55 UTC | 7h 5m |
| 2026-07-19 | GTI8603 | ANC → JFK | Jul 19, 16:50 UTC | Jul 19, 22:55 UTC | 6h 5m |
| 2026-07-18 | GTI8603 | - | Jul 18, 22:40 UTC | Jul 19, 14:20 UTC | 15h 40m |
| 2026-07-18 | GTI8603 | - | Jul 18, 17:20 UTC | Jul 19, 14:20 UTC | 21h 0m |
| 2026-07-18 | GTI8603 | ANC → ANC | Jul 18, 16:35 UTC | Jul 19, 14:20 UTC | 21h 45m |
| 2026-07-18 | GTI8602 | JFK → ANC | Jul 18, 07:10 UTC | Jul 18, 14:10 UTC | 7h 0m |
| 2026-07-17 | GTI812 | PVG → ANC | Jul 17, 22:15 UTC | Jul 18, 04:05 UTC | 5h 51m |
| 2026-07-17 | GTI812 | ICN → ANC | Jul 17, 06:00 UTC | Jul 17, 20:10 UTC | 14h 10m |
| 2026-07-16 | GTI9108 | ANC → ICN | Jul 16, 19:10 UTC | Jul 17, 03:05 UTC | 7h 55m |
| 2026-07-09 | GTI518 | - | Jul 9, 00:05 UTC | Jul 9, 07:45 UTC | 7h 40m |
| 2026-07-08 | GTI518 | - | Jul 8, 01:20 UTC | Jul 9, 01:15 UTC | 23h 55m |
| 2026-07-07 | GTI517 | - | Jul 7, 12:55 UTC | Jul 8, 02:05 UTC | 13h 10m |
| 2026-07-07 | GTI518 | ANC → ORD | Jul 7, 04:45 UTC | Jul 7, 10:10 UTC | 5h 25m |
| 2026-07-06 | GTI518 | - | Jul 6, 10:50 UTC | Jul 7, 02:55 UTC | 16h 5m |
| 2026-07-06 | GTI518 | - | Jul 6, 05:20 UTC | Jul 7, 02:55 UTC | 21h 35m |
| 2026-07-06 | GTI517 | - | Jul 6, 04:40 UTC | Jul 7, 02:55 UTC | 22h 15m |
| 2026-07-06 | GTI517 | - | Jul 6, 01:20 UTC | Jul 7, 01:15 UTC | 23h 55m |
| 2026-07-06 | GTI517 | - | Jul 6, 00:00 UTC | Jul 6, 20:55 UTC | 20h 55m |
| 2026-07-05 | GTI8500 | SUU → PSM | Jul 5, 03:05 UTC | Jul 5, 04:20 UTC | 1h 15m |
| 2026-07-04 | GTI8577 | ANC → CVG | Jul 4, 15:30 UTC | Jul 4, 21:20 UTC | 5h 50m |
| 2026-07-04 | GTI8577 | - | Jul 4, 06:15 UTC | Jul 4, 13:40 UTC | 7h 25m |
| 2026-07-04 | GTI8577 | - | Jul 4, 04:50 UTC | Jul 4, 05:05 UTC | 15m |
| 2026-07-03 | GTI8576 | - | Jul 3, 22:45 UTC | Jul 4, 00:55 UTC | 2h 10m |
| 2026-06-28 | GTI8296 | NGU → HHN | Jun 28, 19:49 UTC | Jun 28, 20:09 UTC | 20m |
| 2026-06-28 | GTI8296 | NGU → HHN | Jun 28, 02:05 UTC | Jun 28, 19:09 UTC | 17h 5m |
| 2026-06-27 | GTI8296 | NGU → HHN | Jun 27, 14:05 UTC | Jun 27, 23:00 UTC | 8h 55m |
| 2026-06-27 | GTI8174 | - | Jun 27, 08:44 UTC | Jun 27, 10:19 UTC | 1h 35m |
| 2026-06-26 | GTI8174 | - | Jun 26, 23:04 UTC | Jun 27, 04:29 UTC | 5h 25m |
| 2026-06-26 | GTI8174 | - | Jun 26, 04:30 UTC | Jun 26, 20:24 UTC | 15h 55m |
| 2026-06-25 | GTI8174 | - | Jun 25, 23:19 UTC | Jun 26, 20:24 UTC | 21h 5m |
| 2026-06-25 | GTI8173 | - | Jun 25, 21:20 UTC | Jun 26, 20:24 UTC | 23h 5m |
| 2026-06-25 | GTI8173 | - | Jun 25, 19:20 UTC | Jun 26, 19:09 UTC | 23h 50m |
| 2026-06-25 | GTI8173 | - | Jun 25, 17:49 UTC | Jun 26, 14:29 UTC | 20h 40m |
| 2026-06-25 | GTI8174 | - | Jun 25, 13:05 UTC | Jun 25, 14:34 UTC | 1h 30m |
| 2026-06-25 | GTI8174 | - | Jun 25, 11:30 UTC | Jun 25, 11:39 UTC | 10m |
| 2026-06-25 | GTI8174 | - | Jun 25, 01:40 UTC | Jun 25, 07:30 UTC | 5h 50m |
| 2026-06-24 | GTI8174 | - | Jun 24, 16:14 UTC | Jun 24, 23:40 UTC | 7h 25m |
| 2026-06-23 | GTI8173 | - | Jun 23, 04:25 UTC | Jun 23, 16:39 UTC | 12h 15m |
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 N439GT page for operator, model, and routing details .