1 December 2105 - Loss of seperation Amsterdam Airport Schiphol

Notification

On 1 December 2015, a loss of separation occurred between two arriving aircraft to Amsterdam Airport Schiphol. LVNL has reported this incident to the Dutch Safety Board and is conducting its own investigation.

Incident investigation

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.

Description

In the morning of 1 December 2015, a loss of separation occurs between two arriving aircraft to Amsterdam Airport Schiphol. The situation arises during parallel approaches from the north to runways 18R and 18C. An Airbus A320 approaches for a landing on 18C, while a Fokker F70 approaches for a landing on 18R. Both aircraft are descending.

The loss of distance arises when the A320 descents to a level which the F70 just has passed. At that moment the speed of descent of the A320 is greater than the speed of descent of the F70. The minimum distance between the two aircraft is 1.4 nautical miles horizontally and 500 feet vertically.

In the phase of the approach in which the flights are at that moment, the separation standard is 3 nautical mile horizontally or 1,000 feet vertically. This standard applies until the moment when both aircraft are stabilized on the part of the instrument landing system which ensures the ideal course line (localizer) to the runway. This occurred shortly after reaching the minimum separation.

Both aircraft land safely.

Investigation results

LVNL has completed its investigation of this incident. A summary of the incident is described below.

Summary

A parallel approach was taking place on the Polderbaan (18R) and the Zwanenburgbaan (18C) at Amsterdam Airport Schiphol. The Airbus 320 was approaching from the south, to land on the Zwanenburgbaan, and the Fokker 70 was approaching from the west in order to land on the Polderbaan.

The approach controller for the Polderbaan instructed the Fokker to descend quickly. This involved anticipating the continuation of both flights, by allowing the Fokker to descend quickly enough for a stable final approach and by realising a vertical separation distance of at least 1,000 feet between the Fokker and the Airbus, before both aircraft turn for a parallel approach to their landing.

The pilot of the Fokker confirmed the instruction. Meanwhile, the Airbus descended for its landing on the Zwanenburgbaan, in accordance with instructions from the approach controller. However, the Fokker descended more slowly than the approach controller had expected. As a result, the planned vertical separation of 1,000 feet was not realised. Both aircraft did manage to follow the correct horizontal path, in accordance with plans and instructions.

Both approach controllers, who were sitting directly next to each other, informed the pilots of the Fokker and the Airbus of the parallel operation and of the presence of another plane in their vicinity. The pilots of both the Fokker and the Airbus confirmed that they understood the situation, and the Fokker pilot could see the Airbus. Air traffic control monitored both aircraft precisely, and decided not to give any corrective instructions.

When the Fokker and the Airbus turned in to intercept the signal from the instrument landing systems on their respective runways, the minimum separation distance was reached: 500 feet vertical - more than 152 metres - and 1.4 nautical miles - approx. 2.6 kilometres - horizontal.

Both planes landed safely.

The conclusion of the investigation is that the incident was the result of an incorrect estimation of the Fokker’s vertical flight profile. Air traffic control has acknowledged this. Based on the normal horizontal behaviour of the two aircraft and the confirmation from the Fokker pilot that the Airbus was visible, no corrective instructions were given.

Classification: major incident