# Presentation: 015751

## 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.”**