What happened
On February 10, 2023, an Embraer Phenom 300, registration CS-PHM, was conducting an instrument approach to runway 10 at St. Gallen-Altenrhein (LSZR) using the ILS. The air traffic controller informed the crew that they were number one for the approach and noted a single-engine aircraft would be departing to the northwest.
Simultaneously, a Diamond Aircraft DA 40 NG, registration HB-SHB, departed from runway 28. While the pilot intended to fly toward the Victor waypoint, the aircraft initially flew straight along the runway extended centerline with only a brief right turn. According to the Visual Approach Chart (VAC), a right turn toward the north is required following a departure from runway 28 to mitigate conflict risks.
As the DA 40 NG continued straight, the air traffic controller issued multiple instructions to the pilot to initiate the right turn. The pilot acknowledged the transmissions by repeating his callsign but did not execute the turn. At 14:26, the crew of the CS-PHM spotted the approaching aircraft and increased their descent rate. Simultaneously, the Traffic Alert and Collision Avoidance System (TCAS) issued a Resolution Advisory (RA) to descend. The two aircraft crossed paths approximately 2.5 NM west of the runway threshold at an altitude of 2500 ft AMSL, with a horizontal separation of roughly 150 m and a vertical separation of about 400 ft.
The investigation
The investigation examined flight tracks, radio communications, and the operational procedures at St. Gallen-Altenrhein. The SUST established that the pilot of the HB-SHB was heavily absorbed in flight maneuvering tasks during the departure phase. The investigation also reviewed historical data, noting that similar conflicts between IFR arrivals on runway 10 and VFR departures from runway 28 have occurred previously at this aerodrome.
Findings
- The primary cause of the near-collision was that the pilot of the HB-40 NG maintained a straight course after takeoff instead of initiating the prescribed right turn.
- The pilot of the HB-SHB demonstrated significantly impaired situational awareness, as evidenced by the failure to follow controller instructions despite acknowledging radio calls.
- The operational procedures at St. Gallen-Altenrhein, which frequently involve simultaneous arrivals and departures in opposite directions, create an inherent safety deficit.
- The TCAS on the CS-PHM functioned as a critical safety net, providing a timely resolution advisory that helped prevent a collision.