On Wednesday 9 October, two aircraft approaching the Schiphol Oostbaan - runway 04/22 – flew closer together than is permitted by the separation minima. LVNL (Air Traffic Control the Netherlands) is conducting an investigation into this occurrence itself and reported the occurrence to the Onderzoeksraad voor Veiligheid (Dutch Safety Board).
Description of occurrence
There was a strong west-southwesterly wind and various storms in the area around the airport.
A Bombardier DH8D (DH8D) aircraft was approaching to land on runway 04/22 (the Schiphol East runway) from the west. Coming in from the east, an Airbus A320 (A320) aircraft was on approach to land on the Schiphol East runway. Both aircraft were descending.
The approach controller for the Schiphol East runway instructed the DH8D to descend to an altitude of 3,000 feet (900 meters). The A320 was instructed to descend to flight level 45 (1,200 meters). The approach controller gave the DH8D instructions for a route to the final approach. The aircraft was still descending to 3,000 feet (900 meters) and passed flight level 45 (1,200 meters) at the time when the aircraft was turning to pick up the Instrument Landing System (ILS) for the final approach. The A320 was already flying at flight level 45 (1,200 meters) and received heading instructions to pick up the Instrument Landing System (ILS) for the final approach behind the DH8D. As a result of the strong wind, the overall traffic situation developed differently than the approach controller had expected. The approach controller saw that the heading instruction given to the A320 would not be sufficient to maintain the required minimum separation between the aircraft and gave the A320 additional heading instructions. However, this did not prevent the two aircraft from coming closer than the required minimum separate distance.
The pilots of both aircraft did not notice anything unusual during their approaches.
Both aircraft landed safely.
Minimum distance
The minimum distance between the two aircraft was 1.7 nautical miles (nearly 3 kilometers) on the horizontal axis and 600 feet (approx. 180 meters) on the vertical axis. The separation standard for the phase of the final approach in which the flights were at that moment is: 3 nautical miles (5.5 kilometers) horizontally or 1,000 feet (300 meters) vertically.
Conclusions
The occurrence was the result of a misjudgment when the approach controller was giving heading instructions, as a result of the strong wind.
Classification: major occurrence