What happened
On March 31, 2005, a student pilot operating a Piper Archer (HB-PHU) was conducting a solo VFR flight from Birrfeld to St. Gallen-Altenrhein. After a training session with an instructor, the student decided to proceed with the flight despite deteriorating weather conditions. During the flight, the pilot encountered heavy cloud cover and significantly reduced visibility near Steckborn, which led to a loss of geographical orientation.
While attempting to navigate back toward the Trasadingen VOR, the pilot inadvertently tuned the wrong frequency, mistakenly selecting the Wil VOR instead of the intended Trasadingen frequency. This error, combined with the poor visibility, caused the aircraft to drift into the Zurich control zone.
Simultably, a Piper Arrow (OE-KRT) was conducting an IFR approach to Runway 14 at Zurich Airport. At approximately 11:47 UTC, the two aircraft crossed paths only 0.3 NM apart with a vertical separation of 400 ft. The air traffic controller at Zurich Tower issued two traffic warnings to the crew of the OE-KRT, noting an unidentified aircraft in their vicinity. The student pilot of the HB-PHU eventually realized his error and contacted the tower to identify himself as an uncontrolled aircraft in the area.
The investigation
The investigation established that the student pilot had mistakenly manipulated the navigation radio instead of the communication radio, resulting in the incorrect frequency being active. This error prevented the pilot from receiving the necessary ATIS information and led to a navigation error that placed the aircraft in controlled airspace without authorization. The investigation also reviewed the weather conditions, noting that while the flight was technically permissible under the prevailing weather forecast, the low cloud base and reduced visibility contributed to the pilot's disorientation.
Findings
- The student pilot lost geographical orientation due to the challenging weather conditions and heavy cloud cover.
- Incorrect navigation frequency tuning caused the pilot to follow an unintended radial, leading the aircraft into the Zurich control zone.
- The flight instructor made an inappropriate decision to allow a student pilot to perform a complex navigation task alone in demanding weather conditions.