Report
On Sunday 13 August, as they were approaching the Kaagbaan (06) at Amsterdam Airport Schiphol, two aircraft came closer together than is allowed by the separation minima. This situation arose because one of the aircraft deviated from the intended heading. LVNL is investigating the incident and has reported it to the Dutch Safety Board.
Loss of separation
The horizontal or vertical distance between aircraft in flight is referred to as their ‘separation’. Separation minima have been established to maintain air traffic safety while at the same time making optimum use of airspace. Air traffic control is responsible for maintaining this minimum separation between aircraft in its control zone. When two aircraft come closer together than the separation minima allow, the situation is known as a loss of separation.
The criteria for separation minima have been designed in such a way that they allow enough time to restore the minimum horizontal or vertical separation. An air traffic controller must perform a number of steps in a very short time:
- Detect the loss of separation;
- Identify an effective solution;
- Communicate that solution to the pilot(s) concerned, in the form of instructions (regarding their altitude, bearing and speed);
- Monitor that the pilot(s) follow these instructions so that safe horizontal or vertical separation is restored as quickly as possible.
Incident investigation
LVNL’s primary task with regard to safety is to keep aircraft separated from one another (including aircraft and vehicles on the ground). Air traffic control (ATC) reports all incidents that actually occur within LVNL, in order to learn from them and to reduce the risk of such incidents being repeated. Within LVNL, all reported incidents are investigated in order to continually improve safety.
Situation description
An aircraft type Boeing 777 was approaching from the south to land on the Kaagbaan. A Boeing 787 was approaching from the west to land on the same Kaagbaan.
The approach controller instructed the Boeing approaching from the west to turn to the southwest - heading 240 - to position the aircraft behind the other approaching Boeing. The pilot correctly confirmed this instruction but turned to the southeast, heading 140. As a result, the aircraft turned into the path of the Boeing approaching from the south, resulting in a loss of separation between the aircraft.
The traffic controller noticed this immediately and gave additional instructions to both aircraft to correct the loss of separation that had arisen.
Both aircraft landed safely.
Minimum separation
The smallest separation between the two aircraft was 1.7 nautical miles – approximately 3 kilometres – horizontally and 600 feet – approximately 180 metres – vertically. The separation standard in the phase of the flight that the aircraft were in at the time of the incident is 3 nautical miles (approximately 5.5 kilometres) horizontal or 1,000 feet (approximately 300 metres) vertical.
Conclusion
The incident resulted from the fact that another heading was flown than instructed by air traffic control and confirmed by the pillot. Directly after the moment the aircraft was heading in another direction the air traffic controller gave additional instructions to both aircraft. The loss of separation was corrected and there was no risk of collision.
Classification: significant incident