Federal Aviation Administration

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Weather Factors Impact Analysis
Federal Aviation Administration
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Weather Impact Classification

• Purpose is to classify weather impact on airline
  scheduled flights on an hourly basis by airport
  as
• None
• Minor
• Moderate
• Severe

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Weather Impact ClassificationUnderlying
Principles

• Data must be readily available
• Delay measure used for classification is percent
  on-time arrivals
• Percent of operations in each weather category
  must pass reasonableness test
• Results move in the right direction as the
  weather classifications moves from none to severe

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Impacting Conditions Analyzed

• Wind.
• Ceiling.
• Visibility.
• Severity of local weather conditions.
• Thunderstorms reported at nearby weather
  stations (50 miles).
• Enroute thunderstorms

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Procedure for Determining None, Minor, Moderate,
or Severe Weather Range Values

• For each impacting condition (factor), develop
  frequency distribution report displaying the
  variable value and percent on-time arrivals based
  on flight plan
• Using the frequency data determine the value when
  percent on-time consistently changed to a
  different level
• Using values determined in the previous step,
  develop minimum and maximum values for all
  weather categories (None, Minor, Moderate, and
  Severe)
• Examine the percent of scheduled operations in
  each weather category to determine reasonableness

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Weather Impact ClassificationExample of an
Airport Scenario with Ranges and Weights
A Factor Weight is applied to each impacting
condition (0 not significant, 1 significant, 2
very significant, 3 extremely significant).
For each factor, the max and min range values
were determined by the frequency distribution and
impact on percent on-time arrivals based on
flight plan. Overall score is the weighted
average of the weather factors
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