Hazardous Weather

The rapid development of cumulous nimbus and associated thunderclouds is a frequent hazard on hot humid summer days. They lead to two hazards, lightning and turbulence.

Lightning:
Two interesting articles on the impact of lightning on flying are:
1) Accident report of lightning strike on ASK-21 in England 1999. This is an excellent but sobering report.
2) Uman & Rakov 2003 paper analyses the impact of lightning on aircraft
3) An interesting video clip of lightning striking an aircraft in Japan

Turbulence:
Turbulence can occur in strong winds and wind shear which is found near thunderstorms as well as adjacent to hilly terrain when the winds are strong. In turbulent conditions it is especially important to anticipate possible dangers to ensure that you do not put yourself into an unrecoverable position. The following two links describe fatal accidents that occurred just 3 weeks and 50 miles apart, at the same altitude with similar winds and gnarly mountains. In both the Ventus accident and the Steve Fossett accident they were flying quite close to terrain, and both were hit by unexpected extreme turbulence caused by a combination of wind, terrain, and thermal activity. Both accidents seem to fit very well with what Martin Hellman calls "99.9% safe maneuvers" -- things we can do without event many, many times, which then build up a confidence in our skill. But that's really complacency masquerading as confidence. The danger is that a combination of events then come together at just the wrong time, turning an otherwise normal and "safe" maneuver into a fatal one. "Unusual" turbulence, wind, etc. is a good indicator of the one-chance-in-a-thousand that can kill even experienced pilots. Unusual isn't the same as impossible.