Summary
Perth ATS assigned the aircraft an altitude of FL330 on descent from FL370. However, the radar mode C display of the aircraft showed the aircraft descending through FL330 to a final level of FL323. When the air traffic controller queried the crew, the pilot verified FL330. The mode C readout then showed the aircraft climbing and then maintaining FL330. When the aircraft descended below FL330, a Fokker F28 was at FL310, and positioned 4 NM away.
Occurrence summary
| Investigation number | 199805323 |
|---|---|
| Occurrence date | 20/11/1998 |
| Location | 228 km N Perth, Aero. |
| State | Western Australia |
| Report release date | 20/08/1999 |
| Report status | Final |
| Investigation type | Occurrence Investigation |
| Investigation status | Completed |
| Mode of transport | Aviation |
| Aviation occurrence category | Loss of separation |
| Occurrence class | Incident |
| Highest injury level | None |
Aircraft details
| Manufacturer | Fokker B.V. |
|---|---|
| Model | F28 |
| Registration | VH-EWD |
| Serial number | 11208 |
| Sector | Jet |
| Operation type | Air Transport High Capacity |
| Departure point | Karratha, WA |
| Destination | Perth, WA |
| Damage | Nil |
Aircraft details
| Manufacturer | Saab Aircraft Co. |
|---|---|
| Model | A340 |
| Registration | 9V-SJB |
| Serial number | 32-40062 |
| Sector | Turboprop |
| Operation type | Air Transport High Capacity |
| Departure point | Singapore |
| Destination | Perth, WA |
| Damage | Nil |