FAA Runway Friction Program Runway Condition Determination, Reporting, and Report Dissemination Workshop Rick Marinelli, P.E., Manager, Airport Engineering Division June 20, 2006

HISTORY FAA started conducting runway friction measurement research with NASA and USAF in the late 60s. No direct relation to aircraft performance was found, but devices could be used for determining when runway surface maintenance was needed.

WINTER RUNWAY FRICTION MEASUREMENT AND REPORTING WORKING GROUP FAA NASA Transport Canada Airports Council International American Association of Airport Executives Air Transport Association Regional Airline Association Air Line Pilots Association

1995 GROUP REPORT Summarized history of runway friction measurement. Noted the Transport Canada system (Canadian Runway Friction Index). Findings: “All FAA-approved CFME and DECs produce statistically equal measurement values…” on certain surface conditions when Mu <= 40. “NASA research has proven that friction values…can be related to aircraft tire braking performance.” “Subjective braking action reports do not correlate to aircraft braking performance.”

1995 GROUP RECOMMENDATIONS Require airports to conduct and report friction measurements. FAA should improve guidance for airports. FAA should fund airports’ purchases of runway friction testers. Continue research. Form a working group to develop operational criteria.

FAA ACTIONS Revised FAA Advisory Circulars to improve guidance: “It is not necessary to report the type of friction measuring device since the friction numbers below 40 read essentially the same for all approved devices.” CFME and DECs are eligible for federal funding. Joint Winter Runway Friction Measurement Program formed. Acquired a fleet of runway friction testing equipment to participate in research.

FAA GUIDANCE FOR AIRPORTS Advisory Circular 150/5320-12, Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces. Lists approved CFME. Advisory Circular 150/5200-30, Airport Winter Safety and Operations. Lists approved decelerometers. Provides guidance for conduction operational friction tests. Limits are compacted snow, ice, loose snow to 1”, slush to 1/8”. FAA supports the use of friction testers for both maintenance and operational purposes. Mu readings are less subjective than braking action reports and are considered another piece of information that a pilot can use in decision-making.

Continuous Friction Measuring Equipment (CFME) Provides a continuous trace of the runway length averaging patchy conditions. FAA-Approved CFME: Airport Surface Friction Tester Safegate Friction Tester Mu Meter Tatra Friction Tester Runway Friction Tester Skiddometer Griptester Friction Tester Runar Runway Analyser And Recorder

DECELEROMETERS Provide spot readings, generally concentrating on contaminated areas. Runway tests take longer than with CFME. FAA-Approved Decelerometers: Bowmonk Decelerometer Tapley Decelerometer TES ERD Mk3 Decelerometer Vericom VC3000 RFM Decelerometer

TRANSMITTING INFORMATION Advisory Circular 150/5200-30, Airport Winter Safety and Operations Provides guidance on reporting runway conditions. states that transmitting friction readings from airport personnel to ATC should be specified in a letter of agreement between them. Reports may also be provided to airport users. Advisory Circular 150/5200-28, Notices to Airmen (NOTAMs) for Airport Operators Provides guidance in providing information directly to pilots. FAA Order 7930.2, Notices to Airmen Provides instructions to Air Traffic personnel on issuing NOTAMs. FAA Order 7110.65, Air Traffic Control Provides instructions to Air Traffic personnel on relaying runway condition information. Specifies that runway friction values should be included on the Automatic Terminal Information Service (ATIS), and provided to pilots on request. Aeronautical Information Manual Provides information to pilots regarding the benefits and limitations of runway friction reports.

JOINT WINTER RUNWAY FRICTION MEASUREMENT PROGRAM FAA: provides equipment and personnel for testing in the U.S., Canada, and Europe. sponsors the membership of a representative to Committee E-17 on Tire Pavement Systems of the American Society for Testing and Materials. participates in the International Meeting on the Performance of Aircraft on Contaminated Runways sponsored by Transport Canada. co-chairs the AAAE Northeast Chapter Snow Symposium R&D Committee.

RECENT DEVELOPMENTS Further testing has shown that friction testers do NOT provide equal readings. FAA Advisory Circular revised: “The friction report should identify the friction tester type…” ASTM Committee E-17 accepted a task to develop and International Runway Friction Index (IRFI) and an Aircraft Friction Index (AFI). IRFI – Standardized friction number regardless of device used. AFI – Aircraft braking friction based on IRFI.

INTERNATIONAL RUNWAY FRICTION INDEX Does not address the braking performance of an aircraft. Can be used by airport maintenance staff to monitor the winter runway friction characteristics for runway maintenance/clearing actions. Accuracy is unknown for mixed snow/ice/slush conditions. Requires an extensive calibration network consisting of an international benchmark device and multiple regional and local devices. Recalibration frequency based on unknown “time stability of devices.”