Lead Time Aviation Verification Onset and Cessation of Ceiling and Visibility Flight Category Conditions (IFR, MVFR, VFR) at FAA Core Airports NWS Aviation Services Branch Aviation Services Virtual Workshop April 16, 2013

Lead Time Accuracy Requirements Identified by Joint FAA/NWS Traffic Flow Management (TFM) Weather Requirements Working Group (TRWG) Performance-Based Weather Information Requirements –Linked to Decisions for Traffic Management Initiatives –Accuracy needed at decision points prior to onset and cessation New Verification Method, Different than Traditional Method –Probability of Detection (POD) and False Alarm Ratio (FAR) only at time of onset and cessation, not throughout event duration Verification Metrics to Baseline Current Support against New Performance-Based Requirements –NWSH Performance Branch developed modified version of Stats on Demand 2

Lead Time Accuracy Requirements 3 Accuracy Criteria Needed for Time of Onset and Cessation of IFR, MVFR, VFR Conditions

Lead Time to Cig/Vis Event Example 4 MVFR Onset 0536Z VFR Cessation 0536Z MVFR Forecast Onset 0500Z VFR Forecast Cessation 0500Z

TAF Lead Time - IFR Onset POD Hour Lead Time to Onset of IFR Conditions at Core Airports Probability of Detection Number of Events/Forecasts 75%

TAF Lead Time – IFR Onset FAR Hour Projection to Onset of IFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - IFR Onset Timing Error 7 Mean Absolute Timing Error: 2-4 Hour Lead Time to Onset of IFR Conditions 30 min Number of Events/Forecasts Timing Error (minutes)

TAF Lead Time - IFR Cessation POD Hour Lead Time to Cessation of IFR Conditions at Core Airports 75% Number of Events/Forecasts Probability of Detection

TAF Lead Time - IFR Cessation FAR Hour Projection to Cessation of IFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - IFR Cessation Timing Error 10 Mean Absolute Timing Error: 2-4 Hour Lead Time to Cessation of IFR Conditions 30 min Number of Events/Forecasts Timing Error (minutes)

TAF Lead Time - MVFR Onset POD Hour Lead Time to Onset of MVFR Conditions at Core Airports 75% Number of Events/Forecasts Probability of Detection

TAF Lead Time - MVFR Onset FAR Hour Projection to Onset of MVFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - MVFR Onset Timing Error Hour Lead Time to Onset of MVFR Conditions at Core Airports 30 min Number of Events/Forecasts Timing Error (minutes)

TAF Lead Time - MVFR Cessation POD Hour Lead Time to Cessation of MVFR Conditions at Core Airports 75% Number of Events/Forecasts Probability of Detection

TAF Lead Time - MVFR Cessation FAR Hour Projection to Cessation of MVFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - MVFR Cessation Timing Error 16 Mean Absolute Timing Error: 2-4 Hour Lead Time to Cessation of MVFR Conditions 30 min Number of Events/Forecasts Timing Error (minutes)

TAF Lead Time - VFR Onset POD Hour Lead Time to Onset of VFR Conditions at Core Airports 75% Number of Events/Forecasts Probability of Detection

TAF Lead Time - VFR Onset FAR Hour Projection to Onset of VFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - VFR Onset Timing Error Hour Lead Time to Onset of VFR Conditions at Core Airports 30 min Number of Events/Forecasts Timing Error (minutes)

TAF Lead Time - VFR Cessation POD Hour Lead Time to Cessation of VFR Conditions at Core Airports 75% Number of Events/Forecasts Probability of Detection

TAF Lead Time - VFR Cessation FAR Hour Projection to Cessation of VFR Conditions at the Core 30 Airports 25% Number of Events/Forecasts False Alarm Ratio

TAF Lead Time - VFR Cessation Timing Error 22 Mean Absolute Timing Error: 2-4 Hour Lead Time to Cessation of VFR Conditions 30 min Number of Events/Forecasts Timing Error (minutes)

Summary Lead Time Accuracy Requirements –Decision process needs timing of Onset/Cessation of events impacting TFM on scale of tens of minutes New Verification Method, Different than Traditional Method –Preliminary Flight Category verification results show significant gap between accuracy baseline and decision process needs –TAF hourly time scale too coarse to meet need of TFM decisions –Model guidance time scale likely to lead to similar results Next Steps for Lead Time Assessment Tool –Wind Direction Changes, Thunderstorms, Model Guidance –Accessible on Performance Management Website –Training for Lead Time Verification Method and Results Interpretation 23