Low Clouds and Fog

November in the U.S. means the risks from thunderstorms have disappeared everywhere except the Gulf Coast region as a new set of problems emerge, from icing to turbulence to low clouds, fog, and high winds. A breakdown of accident statistics helps tell us where to focus our attention first. Using a 2003-2007 study, we find that where weather was a cause or contributing factor, low ceilings and visibility were the #2 factors, involved in 18 percent of all weather-related accidents.

Tim Vasquez

Thursday, October 20, 2016 at 12:00 AM ET

Verified

Key Takeaways:

Low ceilings and visibility (fog and low clouds) are leading weather-related accident factors, particularly for Part 135 operations, due to less equipped and unfamiliar airports.
Automated weather observation systems (ASOS) have limitations in accurately reporting ceilings and prevailing visibility, necessitating pilot caution and cross-referencing with other data.
Pilots must understand various fog and low cloud formation mechanisms, get comprehensive weather briefings, continuously monitor rapidly changing conditions, and strategically plan alternates to enhance safety.

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Using a 2003-2007 study, we find that where weather was a cause or contributing factor, low ceilings and visibility were the #2 factors, involved in 18 percent of all weather-related accidents. Most of this involved continued VFR flight into IMC, which shouldn’t be a factor for instrument-rated pilots. Other weather-related causes were a wide assortment of factors from lightning, icing, and turbulence to carb icing, high density altitude, and wind shear. But only high winds and crosswinds exceeded the threat posed by low ceilings and visibility.