What happened
On July 10, 1999, at 07:28 UTC, a Cessna 182, registration HB-CVK, departed Geneva Airport for Montelimar under visual flight rules (VFR). During the flight, the pilot encountered cloud cover and expressed a desire to maintain 3000 ft to stay clear of the weather. The Geneva Tower controller, noting the presence of an approaching Boeing 737 (KLM 1927) on the ILS runway 05 approach, authorized the pilot to climb only to 3500 ft.
To avoid entering clouds, the pilot of HB-CVK performed a 360-degree left turn and continued to climb, eventually reaching 4500 ft. This unauthorized ascent placed the light aircraft very close to the ILS approach path. Consequently, the Boeing 737 received a TCAS resolution advisory, forcing the crew to climb from 4900 ft to 5500 ft to maintain separation. The separation between the two aircraft was reduced to approximately 1.4 NM and 400 ft.
The investigation
The investigation examined the flight paths, radio communications, and meteorological conditions at the time of the incident. Investigators reviewed the transcript of the communications between the Geneva Tower and the Geneva Terminal Control Area (TMA). The inquiry established that the pilot of HB-CVK did not read back the altitude restriction of 3500 ft. Furthermore, the investigation looked into the timing of the frequency transfer from the Tower to the TMA, noting that the transfer occurred immediately after the pilot mentioned being unable to maintain his heading without hitting clouds.
Findings
- The pilot of HB-CLV was flying in difficult meteorological conditions, specifically attempting to stay within visual flight conditions (VMC) while avoiding clouds.
- The pilot performed an unauthorized climb well above the 3500 ft limit set by the controller.
- The pilot failed to properly read back the altitude restriction provided by the Tower.
- The transfer of the aircraft from the Tower frequency to the TMA frequency occurred at an inopportune time, shortly after the pilot had expressed difficulty with the weather, which contributed to the lack of coordination.
- The proximity of the VFR aircraft to the ILS centerline created a significant loss of separation with the commercial airliner.