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 (LCV), encompassing fog and low clouds, emerge as leading weather-related accident factors in colder months, particularly for Part 135 operations.
Understanding the definitions and measurement methods for ceilings and visibility, along with potential limitations of automated systems, is crucial for accurate weather assessment.
Different types of fog (radiation, advection, upslope) form under specific conditions; recognizing these patterns aids in anticipating hazardous LCV and planning accordingly.
Pilots are advised to always obtain comprehensive weather briefings, strategically plan alternates based on the type of IMC, and continuously enhance their meteorological expertise for improved situational awareness.

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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.