What happened
On January 6, 2015, at approximately 11:57 AM, a Piper PA-28-181 operating under Instrument Flight Rules (IFR) and a Comco C42 B flying under Visual Flight Rules (VFR) experienced two separate close approaches within the Class C airspace of Düsseldorf Airport. The Piper aircraft, an IFR training flight carrying a flight instructor and a student, was maintaining a steady altitude of 3,900 ft AMSL.
Air Traffic Control (ATC) provided the Piper crew with two traffic advisories regarding the ultralight aircraft. The first advisory, issued at 11:56:21, placed the traffic at the eleven o'clock position at a distance of 3 miles. The second advisory, issued at 11:56:54, indicated the traffic had closed to one mile at the twelve o'clock position. Despite these warnings, the Piper crew responded only that they were "looking out."
The first close encounter occurred at 11:57:18, with a minimum horizontal separation of 0.156 nautical miles and a vertical separation of 300 feet. A second encounter followed at 11:58:18, where the horizontal distance was 0.414 nautical miles and the vertical separation was 0 feet. The pilot of the Comco C42 B reported that he had not noticed any crossing aircraft during his flight, which had taken him through several locations including Borkenberge and Wesel.
The investigation
The BFU examined radar data and radio communications transcripts provided by the air traffic control organization. The investigation reviewed the flight paths of both aircraft, the altitude profiles, and the specific instructions issued by the controller. The investigation also considered meteorological conditions, noting that while the weather was CAVOK, the VFR pilot reported slight haze that may have limited downward visibility.
Findings
- The Comco C42 B climbed above 3,500 ft AMSL, placing it within the controlled Class C airspace of Düsseldorf.
- The Piper crew did not visually identify the traffic until 11:58:04, after the first close approach had already occurred.
- No separation advisories or maneuvering instructions were issued by ATC to the Piper crew prior to the minimum recorded separation distances.
- The VFR pilot was monitoring the frequency but did not observe the IFR aircraft.