What happened
On June 15, 2018, a Beechcraft 1t900, operated by the Swiss Air Force and registered as T-729, was performing an instrument approach to Emmen Airport. While aligned with the Instrument Landing System (ILS) for runway 22, the flight crew observed a bright yellow high-performance paraglider approximately 9 nautical miles from the runway threshold at an altitude of 5,000 feet AMSL. The aircraft passed the paraglider with a lateral separation of roughly 100 meters and a vertical separation of approximately 50 meters. No evasive maneuvers were performed by the crew, and the approach continued without further incident.
The investigation
The investigation established that the paraglider was operating within the Emmen Terminal Control Area (TMA) Sector 3 without authorization. The paraglider pilot had not established radio contact with the Emmen Aerodrome Control Officer (ADCO) and did not attempt to contact the tower following the encounter. Furthermore, the paraglider was not detected by the T-729's Traffic Collision Avoidance System (TCAS) nor was it visible on the air traffic controller's radar. This indicates that the paraglider was either not equipped with a transponder or had the device turned off.
Findings
- The primary cause of the high-risk airprox was the presence of the paraglider within a controlled TMA without the knowledge of air traffic services.
- The lack of electronic surveillance capabilities for the paraglider prevented timely detection by both the aircraft crew and ground controllers.
- The incident highlights a recurring safety deficit regarding small, non-transponder-equipped aircraft operating in controlled airspace.
Safety action
While this summary report does not introduce new recommendations, the investigation noted that a previous safety recommendation (No. 518) had already addressed the systemic need for the Federal Office of Civil Aviation (FOCA) to mandate transponder use for aircraft that pose a danger to large aircraft. The investigation concluded that the consistent implementation of such a mandate could have prevented this specific occurrence.