LWE and Checktime Demo
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Transcript of LWE and Checktime Demo
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LWE and Checktime DemoLWE and Checktime Demo
Scott Landolt & Steve Cristanelli - NCAROctober 27, 2009
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What is LWE, Checktime and WSDDM?
• LWE – Liquid Water Equivalent
• Checktime – Automated Holdover Time (HOT) Algorithm
• WSDDM – Weather System for De-icing Decision Making
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Why use LWE?
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Precipitation Type sensor (HSS)
WXT temperature, humidity, and wind sensor (Vaisala)
Hotplate (Yankee) Weighing Snowgauge
(GEONOR)
Liquid WaterEquivalent System Components
Precipitation Type sensor (Vaisala PWD-22)
Freezing Rain sensor (Campbell)
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Chicago Instrumentation Chicago Instrumentation LocationLocation
X
ASOS site LWE site
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LWE Display DemoLWE Display Demo
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Marshall Field Site testing FY08Marshall Field Site testing FY08
List the dates that obtained data for List the dates that obtained data for including the number of hours:including the number of hours:
DateDate Hours of Hours of datadata
Nov. 11, 2007Nov. 11, 2007 66Dec. 20 2007Dec. 20 2007 55
Total hours: Total hours: 144144
Thank you
Wind Enhancement of LWE due to 10 degree angle of a wing
Based on paper in Journal of Aircraft: “Common Snowfall Conditions Associated with Aircraft Takeoff Accidents”,Rasmussen et al. (2000)
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Marshall Field Site testing FY08Marshall Field Site testing FY08
List the dates that obtained data for List the dates that obtained data for including the number of hours:including the number of hours:
DateDate Hours of Hours of datadata
Nov. 11, 2007Nov. 11, 2007 66Dec. 20 2007Dec. 20 2007 55
Total hours: Total hours: 144144
Insert image of snow pans
Thank you
Wind Enhancement of LWE due to 10 degree angle of wing: 10º pan compared to 0º pan using error rejection
criteria
Based on paper in Journal of Aircraft: “Common Snowfall Conditions Associated with Aircraft Takeoff Accidents”,Rasmussen et al. (2000)
Factor of 1.8 larger snow
catch on a 10 degree surface
for a wind speed of 6 m/s
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Snow rate
Wind enhanced rate
Raw precipitation rate
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http://www.rap.ucar.edu/projects/winter/CLE
Online Cleveland LWE display URL
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How does LWE relate to Checktime?
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Inputs to Check Time: 1. Precipitation rate (every minute) enhanced by wind (10 degree effect)
2. Wind speed (every minute)
3. Temperature (every minute)
4. Precipitation type (every minute)
5. Fluid type and concentration
6. Regression equations that relate holdover time to precipitation rate and ambient temperature (from APS report)
Output:
Fluid Expiration time every minute (wall clock time, or Check Time) for given fluid type and concentration
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Checktime Display
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Checktime Display
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Radio MessageRadio Message
At 1630 local, temperature -3C, Light Snow, At 1630 local, temperature -3C, Light Snow, Checktime for Type IV Kilfrost ABC-S Plus Checktime for Type IV Kilfrost ABC-S Plus is 16:50is 16:50
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Impact of Time Variation of Precipitation Impact of Time Variation of Precipitation Rate, Temperature, and Wind Speed on Rate, Temperature, and Wind Speed on
Holdover TimeHoldover Time Data from Denver, Chicago and Pittsburgh all Data from Denver, Chicago and Pittsburgh all
showed that time variation of precipitation has showed that time variation of precipitation has a significant effect on Holdover Timea significant effect on Holdover Time– On average, 50% of the Instantaneous HOTs On average, 50% of the Instantaneous HOTs
longer than Check Time HOTs.longer than Check Time HOTs.– 15% of the Instantaneous HOTs a factor of 1.25 15% of the Instantaneous HOTs a factor of 1.25
longer than Check Time HOTs (a potential safety longer than Check Time HOTs (a potential safety issue). issue).
– 5% of the Instantaneous HOTs a factor of 1.5 long 5% of the Instantaneous HOTs a factor of 1.5 long than Check Time HOTsthan Check Time HOTs
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2008/2009 User Feedback2008/2009 User Feedback DenverDenver
– LWE rates found to accurately reflect operational experience: LWE rates found to accurately reflect operational experience: Example: LWE system reporting of heavy snow during the April 17Example: LWE system reporting of heavy snow during the April 17 thth
event confirmed due to the repeated deicing of 757 aircraft (4 times), event confirmed due to the repeated deicing of 757 aircraft (4 times), and return for deicing a fifth time. and return for deicing a fifth time.
– Found the precipitation type reporting on LWE to be useful. Found the precipitation type reporting on LWE to be useful.
– Tend to use Check Time over LWE system due to the direct Tend to use Check Time over LWE system due to the direct reporting of current Holdover time (expiration time) and more reporting of current Holdover time (expiration time) and more accurate HOT (than instantaneous).accurate HOT (than instantaneous).
– Used the Check Time system to determine when to transition Used the Check Time system to determine when to transition from Type I only to two step Type I and Type IV operationfrom Type I only to two step Type I and Type IV operation
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Current StatusCurrent Status• User feedback positive with regard to the useability and usefulness of the snow LWE. More feedback desired, however. • Users asking to use the systems operationally. • Before can, however, need the FAA to approve.
Remaining Issues:1. Communication to the pilot
- Majority of users prefer message via radio frequency.- Radio frequencies hard to get at airports. - Display on the web.- Product on a Blackberry
2. Approval of LWE snow system for operational use. FAA working on.
3. Expansion to include other precipitation types - Freezing rain and drizzle (2008-2009)- Ice pellets (2009-2010)
4. Approval of Check Time system for operational use.
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SurveySurvey
ATIS – Current time is _____ATIS – Current time is _____– Visibility __________Visibility __________– Temperature ______Temperature ______
Current System HOT Current System HOT – Snow Intensity Chart ________Snow Intensity Chart ________– HOT _________HOT _________
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SurveySurvey LWE (Radio Frequency)LWE (Radio Frequency)
– Temperature _______ Temperature _______ – Intensity __________Intensity __________– HOT (Volume 1 holdover chart) ______HOT (Volume 1 holdover chart) ______
Checktime (Radio Frequency)Checktime (Radio Frequency)– Start time of Type IV ________Start time of Type IV ________– Checktime _________Checktime _________– As close to runway as possible, new checktime As close to runway as possible, new checktime
______, Current time ____________, Current time ______
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SurveySurvey
Did you have to return for De-icing?Did you have to return for De-icing?– If yes, answer these questionsIf yes, answer these questions
Did the time expire? _____Did the time expire? _____ Was the fluid contaminated? _____Was the fluid contaminated? _____ Preemptive? _____Preemptive? _____
Additional training and/or feedback can be found at – http://www.rap.ucar.edu/projects/winter/ORD
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WSDDM