sensors Mode-S transponder
AE535D
ICAO 24-bit transponder address
Currently assigned to 11-20421 · SIKORSKY UH-60 Black Hawk
- Hex
- AE535D
- Octal
- 53451535
- Decimal
- 11,424,605
- Tail
- 11-20421
- Type
- H60
- Flights observed
- 12
- Distinct callsigns
- 1
- Country
- -
- Last broadcast
- 1d ago
Last known position
Callsign history 1 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| R20421 | - | 12 | 2026-06-01 |
Recent flights last 12
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-06-01 | R20421 | - | Jun 1, 23:10 UTC | Jun 1, 23:20 UTC | 10m |
| 2026-05-30 | R20421 | - | May 30, 21:55 UTC | May 30, 22:05 UTC | 10m |
| 2026-05-19 | R20421 | - | May 19, 23:40 UTC | May 20, 00:05 UTC | 25m |
| 2026-05-12 | R20421 | - | May 12, 11:15 UTC | May 12, 11:45 UTC | 30m |
| 2026-05-06 | R20421 | - | May 6, 07:01 UTC | May 6, 07:10 UTC | 10m |
| 2026-05-06 | R20421 | - | May 6, 05:15 UTC | May 6, 05:25 UTC | 10m |
| 2026-05-06 | R20421 | GRF → OLM | May 6, 03:50 UTC | May 6, 04:45 UTC | 55m |
| 2026-05-01 | R20421 | GRF → GRF | May 1, 04:25 UTC | May 1, 08:10 UTC | 3h 45m |
| 2026-04-30 | R20421 | - | Apr 30, 04:35 UTC | Apr 30, 04:50 UTC | 15m |
| 2026-04-30 | R20421 | - | Apr 30, 03:10 UTC | Apr 30, 04:05 UTC | 55m |
| 2026-04-29 | R20421 | GRF → GRF | Apr 29, 04:39 UTC | Apr 29, 06:10 UTC | 1h 30m |
| 2026-04-13 | R20421 | - | Apr 13, 21:35 UTC | Apr 13, 22:30 UTC | 55m |
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 11-20421 page for operator, model, and routing details .