On 11 March 2015, a loss of separation occurred between two arriving aircraft to Amsterdam Schiphol Airport. LVNL has reported this occurrence to the Dutch Safety Board and is conducting its own investigation.
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, whilst at the same time making optimum use of airspace. Air traffic control is responsible for maintaining these minimum distances between aircraft in its control zone. When two aircraft come closer to one another than the 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 correct the situation before it presents a serious danger. An air traffic controller faced with a loss of separation must undertake 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;
• Ensure that the pilot(s) follow these instructions so that safe separation is restored as quickly as possible.
LVNL’s primary safety task is to maintain the separation of aircraft in the air, and between vehicles and other obstacles when on the ground. Air traffic controllers internally report any safety related occurrence, with the objective to learn lessons from those occurrences, thereby reducing the chance that similar occurrences will take place again in the future. All reported occurrences are investigated by LVNL, as part of LVNL’s ongoing commitment to improve safety.
On 11 March 2015 in the afternoon a loss of separation occurred in the Terminal Manoeuvring Area of Amsterdam Schiphol Airport. The situation arose as an Airbus 320 flew a different heading than instructed by air traffic control, causing a loss of separation with a preceding Boeing 737, which was approaching the same runway at Schiphol. At the closest point of approach, the two aircraft were 1.8 nautical miles (horizontal) and 100 feet (vertical) apart. Both aircraft landed uneventfully. LVNL has reported this occurrence to the Dutch Safety Board and is conducting its own investigation.
Summary of investigation results
In the morning of Wednesday, March 11 th 2015, two aircraft came closer than the separation minimum during their approach to Amsterdam Airport Schiphol. An Airbus 320 (A320) did not follow the instructed course while approaching Schiphol from the west. As a result, the separation between the A320 and another aircraft type Boeing 737 (B737) which was previous in line to approach the same runway. The minimum separation distance was 1,8 NM and 100 ft., while the prescribed separation distance is 3NM or 1000 ft. Both aircraft continued their flights uneventfully and landed safely.
Current rules and guidelines provide air traffic controllers sufficient opportunities to achieve and maintain the required separation as well as options to recover any separation loss. In this unique occurrence the course instruction were wrongly interpreted and executed. In order to restore the separation distance air traffic control gave additional instructions in accordance with the current guidelines. Therefore a change in operational procedures will not have a positive effect on our safety performance. Because of the extraordinary circumstances the investigation results will be used for air traffic control training purposes. The results were also shared with the safety management department of the airline involved to give them the opportunity to inform their crew of the A320.
Classification: major incident