What happened
On April 24, 2015, at approximately 16:59 local time, a serious loss of separation occurred in the departure area of runway 14 at Westerland/Sylt airport. The incident involved a PA-34-220T operating under Instrument Flight Rules (IFR) and a PA-46-310P operating under Visual Flight Rules (VFR).
The pilot of the PA-34-220T had received takeoff clearance for an IFR flight to Lüneburg. During the initial climb, the pilot received several traffic advisories from Bremen Radar regarding the PA-46-310P. Despite these warnings, the pilot of the PA-34-220T reported that the other aircraft was not in sight. As the aircraft continued its climb, the distance to the traffic decreased significantly. At 16:58:49, the controller informed the pilot that the traffic was directly ahead at 2 miles. The pilot responded that a descent would be necessary.
Simultaneously, the PA-46-310P was on a VFR flight from Leipzig to Westerland. The pilot had been instructed by Westerland Tower to follow the ECHO routing due to instrument meteorological conditions (IMC) in the area. At 16:59:12, the tower controller instructed the PA-46-310P to vacate the arrival sector for an IFR departure. The pilot of the PA-46-310P acknowledged and began a right turn. Radar data indicates that the minimum separation between the two aircraft reached a horizontal distance of 0.246 nautical miles and a vertical distance of only 100 feet.
The investigation
The BFU examined radar data from the air traffic control organization and radio communications between the crews and the controllers. The investigation also reviewed meteorological reports for the time of the occurrence. The investigation established that the PA-34-220T pilot experienced extremely poor visibility during the climb, specifically noting that sea fog significantly hindered lateral vision.
Findings
- The primary factor in the proximity was poor visibility caused by sea fog, which prevented the pilot of the PA-34-220T from visually acquiring the traffic despite multiple radar advisories.
- The controller at Bremen Radar did not issue a specific avoidance recommendation, as they were uncertain of the PA-46-310P's intended flight path.
- The PA-46-310P pilot did not have visual contact with the PA-34-220T at any point during the encounter.