Common Operating Picture Example of Forecasts for DFW

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NAS Weather Index (WITI) vs. Combined WITI-FA and
Delta (forecast goodness)
30-day period ending 11/12/2008
NWX 100 is a normally-impacted day
Positive delta Over-forecast of traffic impact
Negative delta Under-forecast of traffic impact
Delta gt /-50 may indicate a forecast issue
November 12, 2008
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En-route and Terminal WITI-FA30-Day Period
Ending 11/12/2008
En route Convection E-WITI (NCWD) vs. E-WITI-FA (
CCFP)
Positive Delta Over-forecast
Negative Delta Under-forecast
Terminal Weather T-WITI (METARs) vs. T-WITI-FA (T
AFs)
Positive Delta Over-forecast
Negative Delta Under-forecast
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9/28/2009
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NAS Wx Index Breakdown by Component Last 7
Days, Ending 11/12/2008
See discussion on Slide 5
9/28/2009
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TWITI, 7-Day Period Ending 11/12/2008, by
NWS Region TWITI shows potential operational
impact of IMC, Wind, Winter precipitation, and
Local convective Wx
Positive Delta (bar) over-forecast
Positive Delta (bar) over-forecast
Terminal Weather T-WITI (METARs) vs. T-WITI-FA (T
AFs)
Negative Delta (bar) under-forecast
Negative Delta (bar) under-forecast
Positive Delta (bar) over-forecast
Positive Delta (bar) over-forecast
Negative Delta (bar) under-forecast
Negative Delta (bar) under-forecast
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Analysis for selected airports/days
Eastern Region / BOS, Sunday, Nov 8, 2008
Under-forecast at BOS (actual ceilings, 600-700
Ft, lower than forecast ceilings, 1300-1500 Ft)
however, no impact on operations due to low
traffic demand on a Sunday
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AvMet Applications Website
For more detailed drill-down and analysis,
please go to www.avmet.com/CWITI

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9/28/2009
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NAS Wx Index (WITI) Breakdown by Cause
Explanation to Slide 3

• NAS Wx Index / WITI software can distinguish the
  following factors
• En-route convective weather. This shows
  convective weather impact on an airports
  inbound/outbound flows within approx. 500-NM
  range. This component does not affect queuing
  delay at the airport.
• Local convective weather. This reflects how
  convective weather in the vicinity (lt 100 NM) or
  directly over the airport reduces airports
  capacity. It may affect queuing delay.
• Wind. Any time there is a wind greater than 20
  Kt, or there is precipitation and wind greater
  than 15 Kt, the corresponding impact is recorded.
  Airport capacity may decrease, i.e. queuing
  delays may increase.
• Snow, freezing rain, ice etc. The corresponding
  impact is recorded. Airport capacity may
  decrease, i.e. queuing delays may increase.
• IMC. Ceiling or visibility below airport specific
  minima fog and heavy rain. The corresponding
  FAA capacity benchmarks for IMC are used. Queuing
  delays may increase.
• Queuing Delay (No Weather) plus Ripple Effects.
  No particular weather factor recorded locally for
  the given airport / given hour but WITI software
  computed that there would be queuing delays. This
  can be simply due to high traffic demand or in an
  aftermath of a major weather event when queuing
  delays linger on (even as the weather has moved
  out).
• Additionally, Ripple Effects are recorded in this
  component. For example, if ORD experiences
  departure queuing delays, its corresponding
  destination airports will get some additional
  arrival queuing delay.
• Other. Includes minor impacts due to
  light/moderate rain or drizzle but
  ceilings/visibility above VFR minima also
  unfavorable RWY configuration usually due to
  light-to-moderate winds (15-20 Kt or even 10 Kt)
  that prevent optimum-capacity runway
  configurations from being used.

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