sensors Mode-S transponder
4A2181
ICAO 24-bit transponder address · allocated to Romania
Currently assigned to YR-HLA · BOEING 737-800
- Hex
- 4A2181
- Octal
- 22420601
- Decimal
- 4,858,241
- Country
- RO
- Tail
- YR-HLA
- Type
- B738
- Flights observed
- 67
- Distinct callsigns
- 14
- Country
- RO
- Last broadcast
- 3h ago
Last known position
Country allocation
The ICAO 24-bit address 4A2181 falls within the block assigned to Romania (RO) by ICAO Annex 10, Volume III. Every aircraft registered in Romania 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 14 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| HLJ2VV | - | 26 | 2026-05-29 |
| HLJ2EY | - | 11 | 2026-05-30 |
| HLJ4AB | - | 9 | 2026-04-19 |
| HLJ3BF | - | 5 | 2026-04-17 |
| HLJ2JK | - | 4 | 2026-05-16 |
| HLJ818F | - | 3 | 2026-04-28 |
| HLJ2GJ | - | 2 | 2026-05-23 |
| HLJ817F | - | 1 | 2026-04-24 |
| HLJ814F | - | 1 | 2026-04-20 |
| HLJ5CG | - | 1 | 2026-05-08 |
| HLJ4GK | - | 1 | 2026-05-01 |
| HLJ3HJ | - | 1 | 2026-04-18 |
| HLJ1GL | - | 1 | 2026-05-29 |
| HLJ1AM | - | 1 | 2026-05-29 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-30 | HLJ2EY | - | May 30, 05:10 UTC | May 30, 08:10 UTC | 3h 0m |
| 2026-05-29 | HLJ1AM | BOJ → PRG | May 29, 18:55 UTC | May 29, 20:55 UTC | 2h 0m |
| 2026-05-29 | HLJ1GL | PRG → BOJ | May 29, 16:20 UTC | May 29, 18:10 UTC | 1h 50m |
| 2026-05-29 | HLJ2VV | PRG → PRG | May 29, 05:25 UTC | May 29, 15:20 UTC | 9h 55m |
| 2026-05-28 | HLJ2VV | PRG → PRG | May 28, 07:25 UTC | May 28, 17:25 UTC | 10h 0m |
| 2026-05-27 | HLJ2VV | PRG → PRG | May 27, 04:09 UTC | May 27, 14:15 UTC | 10h 5m |
| 2026-05-26 | HLJ2VV | PRG → PRG | May 26, 05:15 UTC | May 26, 15:09 UTC | 9h 55m |
| 2026-05-25 | HLJ2VV | PRG → PRG | May 25, 05:20 UTC | May 25, 15:05 UTC | 9h 45m |
| 2026-05-24 | HLJ2VV | PRG → PRG | May 24, 05:35 UTC | May 24, 15:30 UTC | 9h 55m |
| 2026-05-23 | HLJ2GJ | PRG → PRG | May 23, 16:10 UTC | May 24, 04:05 UTC | 11h 56m |
| 2026-05-23 | HLJ2VV | PRG → PRG | May 23, 05:15 UTC | May 23, 14:55 UTC | 9h 40m |
| 2026-05-22 | HLJ2EY | PRG → PRG | May 22, 05:20 UTC | May 22, 15:20 UTC | 10h 0m |
| 2026-05-21 | HLJ2EY | PRG → PRG | May 21, 07:40 UTC | May 21, 17:20 UTC | 9h 40m |
| 2026-05-20 | HLJ2VV | PRG → PRG | May 20, 04:15 UTC | May 20, 14:05 UTC | 9h 51m |
| 2026-05-19 | HLJ2VV | PRG → PRG | May 19, 05:10 UTC | May 19, 15:05 UTC | 9h 55m |
| 2026-05-18 | HLJ2VV | PRG → PRG | May 18, 05:30 UTC | May 18, 15:15 UTC | 9h 45m |
| 2026-05-17 | HLJ2EY | PRG → PRG | May 17, 07:25 UTC | May 17, 17:30 UTC | 10h 5m |
| 2026-05-16 | HLJ2JK | PRG → PRG | May 16, 17:50 UTC | May 17, 03:55 UTC | 10h 5m |
| 2026-05-16 | HLJ2EY | PRG → PRG | May 16, 05:25 UTC | May 16, 15:35 UTC | 10h 11m |
| 2026-05-15 | HLJ2VV | PRG → PRG | May 15, 05:30 UTC | May 15, 15:50 UTC | 10h 19m |
| 2026-05-14 | HLJ2VV | PRG → PRG | May 14, 07:25 UTC | May 14, 17:55 UTC | 10h 30m |
| 2026-05-13 | HLJ2VV | PRG → PRG | May 13, 04:10 UTC | May 13, 14:05 UTC | 9h 55m |
| 2026-05-12 | HLJ2EY | PRG → PRG | May 12, 05:00 UTC | May 12, 15:25 UTC | 10h 25m |
| 2026-05-11 | HLJ2EY | PRG → PRG | May 11, 05:55 UTC | May 11, 15:35 UTC | 9h 40m |
| 2026-05-10 | HLJ2JK | PRG → PRG | May 10, 18:55 UTC | May 11, 04:45 UTC | 9h 50m |
| 2026-05-10 | HLJ2VV | PRG → PRG | May 10, 07:10 UTC | May 10, 17:34 UTC | 10h 25m |
| 2026-05-09 | HLJ2JK | PRG → PRG | May 9, 17:45 UTC | May 10, 04:04 UTC | 10h 20m |
| 2026-05-09 | HLJ2VV | PRG → PRG | May 9, 05:15 UTC | May 9, 15:25 UTC | 10h 10m |
| 2026-05-08 | HLJ5CG | PRG → PRG | May 8, 07:14 UTC | May 8, 16:55 UTC | 9h 40m |
| 2026-05-07 | HLJ2VV | PRG → PRG | May 7, 07:40 UTC | May 7, 18:20 UTC | 10h 40m |
| 2026-05-06 | HLJ2VV | PRG → PRG | May 6, 04:25 UTC | May 6, 14:10 UTC | 9h 45m |
| 2026-05-05 | HLJ2VV | PRG → PRG | May 5, 06:45 UTC | May 5, 16:40 UTC | 9h 55m |
| 2026-05-04 | HLJ2VV | PRG → PRG | May 4, 05:15 UTC | May 4, 15:35 UTC | 10h 20m |
| 2026-05-03 | HLJ2VV | PRG → PRG | May 3, 07:10 UTC | May 3, 17:10 UTC | 10h 0m |
| 2026-05-02 | HLJ2GJ | PRG → PRG | May 2, 17:35 UTC | May 3, 04:10 UTC | 10h 34m |
| 2026-05-02 | HLJ2VV | PRG → PRG | May 2, 04:25 UTC | May 2, 14:30 UTC | 10h 5m |
| 2026-05-01 | HLJ4GK | PRG → PRG | May 1, 07:15 UTC | May 1, 17:35 UTC | 10h 20m |
| 2026-04-30 | HLJ2VV | PRG → PRG | Apr 30, 07:35 UTC | Apr 30, 17:40 UTC | 10h 5m |
| 2026-04-29 | HLJ2VV | - | Apr 29, 06:55 UTC | Apr 29, 14:45 UTC | 7h 51m |
| 2026-04-29 | HLJ2EY | - | Apr 29, 04:34 UTC | Apr 29, 06:49 UTC | 2h 15m |
| 2026-04-28 | HLJ2EY | PRG → PRG | Apr 28, 07:00 UTC | Apr 28, 17:10 UTC | 10h 10m |
| 2026-04-28 | HLJ818F | - | Apr 28, 02:40 UTC | Apr 28, 05:50 UTC | 3h 10m |
| 2026-04-27 | HLJ818F | - | Apr 27, 08:20 UTC | Apr 28, 05:50 UTC | 21h 30m |
| 2026-04-27 | HLJ818F | - | Apr 27, 06:20 UTC | Apr 28, 05:50 UTC | 23h 30m |
| 2026-04-27 | HLJ2EY | - | Apr 27, 05:20 UTC | Apr 28, 04:15 UTC | 22h 55m |
| 2026-04-26 | HLJ2VV | PRG → PRG | Apr 26, 07:40 UTC | Apr 26, 18:10 UTC | 10h 30m |
| 2026-04-25 | HLJ2JK | PRG → PRG | Apr 25, 18:40 UTC | Apr 26, 04:45 UTC | 10h 5m |
| 2026-04-25 | HLJ2VV | PRG → PRG | Apr 25, 07:15 UTC | Apr 25, 17:20 UTC | 10h 5m |
| 2026-04-24 | HLJ817F | - | Apr 24, 12:40 UTC | Apr 24, 14:15 UTC | 1h 35m |
| 2026-04-20 | HLJ814F | - | Apr 20, 16:55 UTC | Apr 20, 18:25 UTC | 1h 30m |
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 YR-HLA page for operator, model, and routing details .