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

2. 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.

3. 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

4. 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.”

5. 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.

6. 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.

7. FAA GUIDANCE FOR AIRPORTS
Advisory Circular 150/ , Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces.
Lists approved CFME.
Advisory Circular 150/ , 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.

8. 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

9. 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

10. TRANSMITTING INFORMATION
Advisory Circular 150/ , 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/ , Notices to Airmen (NOTAMs) for Airport Operators
Provides guidance in providing information directly to pilots.
FAA Order , Notices to Airmen
Provides instructions to Air Traffic personnel on issuing NOTAMs.
FAA Order , 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.

11. 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.

12. 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.

13. 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.”