An ATSB report has warned pilots of the dangers associated with flying visually at night.
The report, sub-titled What You Can't See Can Still Hurt You, examines night visual accidents over the 20-year period between 1993 and 2012, concluding, among other things, that night visual flight is sufficiently different from both day VFR and instrument flight to be considered a completely separate skill.
Thirty-six accidents over the period were examined for the report, including 13 when the pilot had a night VFR rating, eight where the pilot had a CIR but was flying visually, five where the pilot was neither night nor instrument rated and 10 when the pilot entered IMC at night.
The report states: "Of the 26 accidents during night visual conditions, half involved a loss of aircraft control, most likely due to the influence of perceptual illusions caused by the lack of visual cues. The other half involved controlled flight into terrain (CFIT), where the pilot probably did not know of the terrain's proximity immediately before impact."
Eight case studies are presented, including the loss of a Saratoga on approach to Moree in 2011, the crash of an ABC helicopter near Lake Eyre and an accident involving a C310 on Bathurst Island. Lessons learned from each case are explained clearly in the report.
An examination of pilot experience showed no correlation between hours flown and night accidents, which shows that all pilots can be vulnerable to night flying illusions.
The conclusion contained this advice for night visual pilots.
"Before every night flight, systematically assess the potential for the flight to encounter dark night conditions by considering the weather conditions, celestial illumination and available terrestrial lighting.
"Only fly in environments that do not exceed your capabilities. In very dark conditions, consider following instrument procedures if you are rated or avoid areas with limited terrestrial lighting if you are not.
"In night visual flight, there is more chance of any pilot becoming influenced by illusions. Have a coping strategy in place, and be prepared to revert to instrument flight to recover from any spatial disorientation."
The full report can be downloaded from the ATSB website.