Notice
On Thursday, 16 May, two aircraft breached the separation minima after departing from Amsterdam Airport Schiphol's Kaagbaan (24) and Aalsmeerbaan (18L), respectively. LVNL is investigating this incident and has reported it to the Dutch Safety Board and the Human Environment and Transport Inspectorate.
Situation and investigation
At the time of the incident, flights departing from Schiphol are routed to the Kaagbaan (runway 24) and Aalsmeerbaan (runway 18L). The Oostbaan (runway 22) is occasionally used for smaller departing aircrafts (general aviation).
A Cessna Citation aircraft reports as ready for departure on the Oostbaan (Runway 22), with a planned route in a south-westerly direction. At the same time, an Embraer 175 aircraft is ready for departure on the Aalsmeerbaan (runway 18L) with a planned southbound route. There are showers south of the Aalsmeerbaan (18L), prompting the tower controller to agree on a specific heading with pilots taking off from this runway to avoid the showers after take-off. Air traffic control agrees that the pilot of the Embraer will prepare for a southwest heading (heading 220).
The pilot of the second Embraer 175 aircraft then also reports on the Kaagbaan (runway 24). This aircraft is scheduled to take-off in a north-westerly direction and the tower controller orders the pilot to enter the runway and wait.
The tower controller informs the radar controller of the planned sequence of departing flights. and subsequently clears the Embraer on Aalsmeer Runway (18L) for take-off. The tower controller then asks the pilot of the Embraer on Kaagbaan if they are ready to take off and clears this aircraft for take-off too. Shortly afterwards, the tower controller asks the pilot of the Cessna if they can depart on the planned route. The pilot confirms and the tower controller clears the Cessna Citation for take-off.
After take-off, the Embraer continues from the Aalsmeer runway (runway 18L) on the agreed south-westerly heading (220) and the pilot reports to the radar controller. Within the separation minima, the aircraft continues on more or less a parallel heading to the Embraer that took off from Kaagbaan (runway 24). The radar controller successively instructs the Embraer from Aalsmeer Runway (Runway 18L) to fly left to the south-east and the Embraer from Kaag Runway to continue right to the north-west. The headings of the Embraer aircraft subsequently diverge and the necessary separation is restored.
Minimum separation
The minimum separation between the two aircraft during this incident was 1.7 nautical miles of horizontal separation (approx. 3.1 kilometres) and 100 feet of vertical separation (approx. 30 metres). Radar controllers use separation criteria of 3 nautical miles (approx. 5.5 kilometres) of horizontal separation and 1,000 feet (approx. 300 metres) of vertical separation in this area of Schiphol Airport. Horizontal separation may initially be less than 3 nautical miles after take-off, provided the headings diverge further than they did here.
Investigation findings and follow-up action
Mentally, the tower controller was preoccupied with the take-off from the Kaagbaan (24) and the subsequent take-off from the Oostbaan (22), with both aircraft departing in a west-south-westerly direction. Partly because of this, the tower controller was under the impression that the Embraer would depart from the Aalsmeerbaan (runway 18L) on the planned southbound route instead of on the agreed south-westerly heading. Once the radar controller coordinates with the tower controller to resolve the situation, the tower controller gets the full picture again. The radar controller had expected the Embraer from the Aalsmeerbaan (runway 18L) on its original southbound route.
LVNL will incorporate the findings of this investigation into a training course for Schiphol air traffic controllers.
Classification: major incident
