What happened
On August 8, 2010, at approximately 11:59 local time, a near mid-air collision occurred in the approach area for runway 24 at Friedrichshafen. The incident involved a Bombardier DHC8-314 operating under Instrument Flight Rules (IFR) on a flight from Saint Catherine, France, and an IkarUS C42 ultralight operating under Visual Flight Rules (VFR) on a flight from Konstanz to Lindau.
The crew of the Bombardier DHC8-314 was executing an ILS approach to runway 24 and had been cleared to descend to 4,000 ft MSL. During the approach, the crew received traffic information regarding an unknown VFR aircraft. While the crew initially noted the aircraft was visible on TCAS but not yet in sight, they later reported that the aircraft had disappeared from the TCAS display. Following a clearance to turn right to 280 degrees, the crew reported that the other aircraft was now in sight. At this point, a TCAS RA (Resolution Advisory) for descent was generated and followed by the crew. Shortly after the maneuver, the Bombardier DHC8-314 passed beneath the Ikarus C42.
The pilot of the Ikarus C42 was navigating via charts, flying around the Friedrichshafen control zone toward Wangen. The pilot reported crossing the path of the twin-engine turboprop at a distance of approximately 1.5 km and a vertical separation of about 100 meters. The pilot noted that the larger aircraft passed underneath the ultralight and did not believe an evasive maneuver was necessary.
Radar records confirmed a minimum horizontal separation of 0.06 nautical miles and a vertical separation of 500 ft.
The investigation
The BFU examined radar recordings from the air traffic service provider and radio communications transcripts. The investigation also reviewed the flight parameters of both aircraft and the meteorological conditions at the time, which featured visibility greater than 10 km and light cloud cover.
Findings
- The Bombardier DHD8-314 was operating under IFR and followed a TCAS RA descent command.
- The Ikarus C42 was operating under VFR and was not in direct communication with the Friedrichshafen tower, though the pilot was monitoring the frequency.
- The separation loss occurred in Class E airspace, where IFR flights are separated from one another, but no separation is required between IFR and VFR flights, though traffic information is provided when possible.
- There were no injuries and no damage to either aircraft or third parties.