On Tuesday 24 December, two aircraft - departing from runway 18L (Aalsmeerbaan) and runawy 24 (Kaagbaan) - flew closer together than is permitted by the separation minima. LVNL (Air Traffic Control the Netherlands) reported the occurrence to the Onderzoeksraad voor Veiligheid (Dutch Safety Board).
Description of occurrence
A Boeing B737-800 (B738) aircraft took off from runway 24/06 (Kaagbaan) for a flight route heading to the west. At the same time, an Airbus A320 (A320) aircraft took off from runway 18L/36R (Aalsmeerbaan) for a flight route heading to the east.
Shortly after take-off, the A320 made an unexpected right turn, thus flying towards the B738 that had just taken off. The radar controller confirmed the situation and immediately instructed both aircraft to secure the separation distance between the two aircraft. These instructions were followed by both aircraft crews. However, this did not prevent the two aircraft from coming closer than the required minimum separate distance.
After resolving the conflict, both aircraft were guided back to their original departure route.
The minimum distance between the two aircraft was 1.8 nautical miles (3 kilometers) on the horizontal axis and 600 feet (180 meters) on the vertical axis. The separation standard for the phase of departure in which the flights were at that moment is: 3 nautical miles (5.5 kilometers) horizontally or 1,000 feet (300 meters) vertically.
The occurrence took place as a result of the switch from the Flight Management System (FMS) to manual controls. In that process, the aircraft made an unintentional swerve to the right. The aircraft crew took corrective action. This action coincided with the corrective action taken by the radar controller.
Classification: significant occurrence