Aviation Decision SupportInFlight and Ground Icing: what do I need to know?

Marcia Politovich, NCAR

• Flight Planning: – Where is it?

• Along my planned route of flight?• What altitude? • Do I need to de-ice prior to takeoff?• Is there freezing precipitation at my destination?

– When is it? • How long will the inflight or ground icing condition continue?• Should I delay my flight until the weather improves?

– How bad will it be?• What’s the forecast severity?• How does that affect my airplane?

• During Flight:– Have conditions changed? – Do I need to request change of flight route, altitude? – Do I need to divert to an alternate airport?

How Do We Find This Info?

What are we looking for?

• Clouds or precipitation• -40C<T<0C• Supercooled liquid

water• Narrower T range• Glaciation • LWC• Drop size

Information sources• Satellite – horizontal extent of

clouds, cloud top temperature, what type of cloud

• PIREPs – where icing is and is not

• METARs – precipitation type and amount, cloud cover, ceiling height, cloud layers

• Radar – extent of precipitation• Soundings – temperature and

moisture profiles at a point• Models – full temperature field,

humidity, condensate

less

more

Products That Can HelpInFlight icing:

– AIRMETs and SIGMETS• National Weather Service forecasts of expected moderate or greater icing over large

areas for 6-h periods

– SIGMETS• National Weather Service forecasts of severe icing – short term, small area, usually

triggered by a pilot reporting severe icing conditions

– CIP and FIP• Automated diagnoses and forecasts of icing including probability, expected severity,

and potential for large-drop icing• Hourly out to 12 h, with 20-km/1000-ft resolution

– TAFs • Show forecast conditions at airports

– Various vendor products• These supplement the products above with different displays and content, and can be

free to the public or available via a subscription service

Your Web Resources• NCAR Research Application Lab, Aviation Applications Program• http://www.ral.ucar.edu/aap/

• Aviation Digital Data System – ADDSYour one-stop-shopping place for AIRMETS, SIGMETS, surface

conditions, TAFS, and automated CIP/FIP guidance over the CONUS

– Operational: http://www.aviationweather.adds.gov/adds/– Experimental: http://weather.aero/

• Aviation Weather Center: http://www.aviationweather.gov/• Additional products generated by NWS

• Alaska Aviation Weather Unit: http://aawu.arh.noaa.gov/• Provides AIRMETS and SIGMETS for Alaska