An Update on the FAA’s EDR Reporting Program Larry Cornman National Center for Atmospheric Research

The Need for Automated Turbulence Reports Turbulence can be a very dynamic and spatially localized phenomena – hence the need for real-time measurements. Pilot reports are problematic in that they are subjective measures of the aircraft response to the turbulence – not quantitative measures of the atmosphere.

In situ Turbulence Measurement and Reporting System Goal: To augment/replace subjective PIREPs with objective and precise turbulence measurements. Features: Atmospheric turbulence metric: eddy dissipation rate (EDR). EDR can be scaled into aircraft turbulence response metric (RMS-g). Adopted as ICAO Standard

EDR vs. RMS-g? EDR is a measure of the turbulent state of the atmosphere. RMS-g is the response of a given aircraft – at a given flight condition – to the turbulence. Both are valid quantities, the issue is what is the appropriate/best use of them?

EDR vs. RMS-g? Reporting EDR from an aircraft requires no additional information. Reporting RMS-g from an aircraft requires information on aircraft type, altitude, weight, and airspeed.

EDR vs. RMS-g? Forecasters, models, scientists want EDR. Pilots would probably want RMS-g. ATC, Dispatch: Since they are talking to a number of users at a time, do they want aircraft specific, or aircraft independent measure? Maintenance would want peak-g.

EDR vs. RMS-g? Given knowledge of aircraft type, airspeed, altitude and weight, EDR can be converted into RMS-g with sufficient accuracy.

median r=0.94 m=0.98 peak r=0.95 m=1.03 Conversion Between EDR and RMS-g: Illustrated with Data from NASA B-757 Aircraft EDR-predicted RMS-g Measured RMS-g 2407 one-minute samples Median Peak

EDR vs. RMS-g? FAA/NCAR position is: Use EDR as the reporting metric for air-ground, air-air, and ground-air. If a given user wants RMS-g, convert EDR at their location.

Increase in Spatial/temporal Coverage: UAL EDR Reports Compared to pireps 1.3 million EDR reports/month from 100 or so aircraft - compared to 55k pireps from all aircraft

EDR on Experimental ADDS Display contains EDR reports, pireps, GTG. Movie loops, cross- sections, etc…

Major Upcoming Activities SWA implementation in CY06/07. Status: preliminary software has been delivered to Honeywell, who is doing integration and testing. SWA Route Structure

GTG Status GTG1 On “Operational ADDS” since March 2003 CAT above FL200 Based on RUC 13/20 Forecasts out to 12 hrs GTG2 On “Experimental ADDS” since Nov 2004 Improved turbulence diagnostics “CAT” above FL100 Based on RUC 13/20 Forecasts out to 12 hrs Textual representation Includes UAL in situ EDR measurements above FL200 GTG2/PIREPS GTG2/EDR GTG1/ADDS Example

Future Airline Participation Discussions ongoing with Delta Airlines. Discussions begun with Northwest Airlines. Future work is contingent on continued FAA funding…

Other Issues Cost/Optimization Since turbulence can be highly-localized and temporally dynamic, having as many measurements (even null) as possible is important. But this has to be balanced by cost considerations. Event-based reporting is a partial, though not optimal, solution (what happened between the events?)

Other Issues, cont’d Resolving the EDR vs. RMS-g issue and international harmonization: ICAO standard is EDR. TAMDAR uses EDR. Will all US carriers use EDR? AMDAR does not use EDR.