What happened
On October 22, 2008, a Cirrus SR22, registration N467BD, was conducting an IFR flight when it experienced a technical malfunction involving the failure of alternator one. Following the electrical issue, the pilot attempted to divert to Zurich Airport. During the approach, the pilot communicated to air traffic controllers that the runway was in sight, despite the aircraft being in a difficult position within instrument meteorological conditions. While executing a tight right-hand turn at a low altitude, the pilot lost control of the aircraft, causing it to strike the ground. At the time of the impact, the aircraft was flying at a high bank angle of between 40 and 8 and 80 degrees at approximately 100 knots.
The investigation
The SUST investigation examined the electrical system, the pilot's management of the alternator failure, and the communication between the cockpit and air traffic control. Investigators found that the pilot's handling of the partially redundant system failure actually worsened the impact of the malfunction rather than mitigating it. The investigation also reviewed the use of onboard navigation aids, noting that the CMax Approach Charts function was used improperly and that the aircraft's electronic horizontal situation indicator was set to an incorrect inbound course. Furthermore, the investigation looked into the aircraft's weight, finding it was approximately 45 kg, or roughly 3%, above the maximum allowable limit defined in the AFM.
Findings
Several contributing factors led to the accident, most notably the loss of control during a steep, low-altitude turn. Key findings included:
- The pilot's management of the electrical failure exacerbated the situation.
- An inaccurate situational awareness led the pilot to provide overly optimistic reports to controllers, which prevented the declaration of an emergency.
- The pilot lacked the necessary approach charts for the diversion airport.
- Inadequate use of available navigation aids and an incorrect course setting on the EHSI.
- Air traffic controllers demonstrated an insufficient understanding of the risks faced by single-pilot, single-engine aircraft operating in demanding weather conditions.
- The pilot'1s decision to perform a demanding maneuver using visual references in IMC, combined with a high approach speed and high aircraft mass, created an unsafe flight envelope.