On Monday 2 November, two aircraft flew closer together than is permitted by the separation minima. The aircraft took off consecutively from the Kaagbaan (24) at Amsterdam Airport Schiphol. 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
With a strong south-westerly wind, an Airbus A320 aircraft (A320) took off from runway 24. One minute later, an Embraer 190 aircraft (E190) took off from the same runway. Both aircraft initially flew the same route, but the E190 caught up with the A320 after take-off.
The E190 overtaking the A320 was observed by air traffic control. Coordination took place between the tower controller and the approach controller. By that time, the A320 had passed 2,000 feet (610 metres) and had switched from tower controller to approach controller. When the E190 had passed 2,000 feet, the aircraft received an additional instruction from the tower controller. As a result, the approach controller and the tower controller both issued instructions to the two individual aircraft to resolve the situation, independently from each other.
During this occurrence, the minimum distance between the two aircraft was approximately 3.3 kilometres (1.8 nautical miles) horizontally and 0 metres (0 feet) vertically. The separation standard is 5.5 kilometres (3 nautical miles) horizontally or 300 meters (1,000 feet) vertically. At the time the minimum distance was reached, the tracks of the E190 and the A320 were diverging, thus increasing their distance.
Conclusions of the investigation
During the first minute after take-off, the E190 was faster than the heavier A320, which reduced the distance between the aircraft. In addition, the A320’s climb to altitude was less steady than that of the E190, which also reduced the difference in altitude between them. The strong headwind is a factor that needs to be considered within this context. Because the aircraft were on a different frequency, and there was not enough communication between the controllers involved, the distance between the two aircraft came within the separation standard.
To prevent reoccurrences, LVNL issued safety communication requesting air traffic controllers to be extra alert for speed differences after take-off.
Classification: major incident