Incident Overview
On April 23, 2021, at approximately 09:02 local time, a serious airprox was recorded roughly one kilometer northeast of the Regionalflugplatz Bern-Belp (LSZB). The event involved two light aircraft operating under Visual Flight Rules (VFR) in Class D airspace. The Swiss Transportation Safety Investigation Board (STSB) conducted a summary investigation to derive safety lessons from the occurrence.
Aircraft and Personnel
The first aircraft was a Robin DR40 with registration HB-KOW, operated by Air-Club d'Yverdon-les-Bains. It was piloted by a Swiss national born in 1946, holding an EASA Private Pilot Licence (PPL(A)) with over 1,376 total flight hours. The second aircraft was a Cessna C172 with registration HB-CWE, owned by Alpaviation AG. This aircraft was engaged in a training flight for a private pilot license, piloted by an instructor born in 1944 holding an Airline Transport Pilot Licence (ATPL(A)) with over 9,300 hours, accompanied by a student pilot.
Sequence of Events
The pilot of HB-KOW intended to land at Bern-Belp. At 08:50, the air traffic controller cleared the aircraft to enter via Route Whiskey and join the right base for Runway 14. The pilot of HB-CWE was subsequently cleared for a left-hand circuit pattern for training purposes.
At 08:57, the controller authorized HB-CWE for a touch-and-go maneuver. Meanwhile, HB-KOW reported passing waypoint W1. At 08:59, the controller observed that HB-KOW was flying a full circle and reiterated the instruction to join the right base for Runway 14. The pilot of HB-KOW acknowledged this instruction.
At 09:02, the controller visually acquired HB-KOW and instructed the pilot to make a right turn to rejoin the left downwind leg for Runway 14, noting that the aircraft was on the wrong downwind. The pilot of HB-CWE reported visual contact with HB-KOW as it turned southwest toward Kehrsatz. At 09:02:30, the minimum separation between the two aircraft was recorded at 0.7 nautical miles horizontally and 100 feet vertically.
Findings and Analysis
The investigation noted that the air traffic controller was managing eleven other aircraft during this period. The pilot of HB-KOW had initially expected to approach Runway 32 due to wind conditions but was cleared for Runway 14. After passing waypoint W1, the pilot flew a full circle, likely misunderstanding the clearance limit. The controller subsequently corrected the pilot's position, leading to the close encounter with HB-CWE, which was executing a training circuit. Both aircraft landed safely without further incident.