Runway Friction Surveys During Winter Operations
FAA Advisory Circular 150/5200-30A, Change 4, titled "Airport Winter Safety and Operations" provides guidance to assist airport owners/operators in the development of an acceptable airport snow and ice control program and to provide guidance on appropriate field condition reporting procedures. In addition to the usefulness for efficient snow and ice removal, field condition reports can enhance aircraft safety when provided to pilots during winter operations. For this reason, many airports use runway friction measurement equipment to provide an indication of the existing friction on runways contaminated by snow or ice during aircraft operations and during snow removal operations. However, there are certain conditions when friction testing should not be attempted because it may lead to erroneous readings. For example, friction testing should not be made on loose snow over 1 inches (2.5cm) or slush over 1/8 inch (3mm) deep.
The FAA's performance specifications for Continuous Friction Measurement Equipment (CFME) were developed from trials conducted at NASA's Wallops Island Flight Facility, and are specifically intended for maintenance measurements of pavement micro-texture on the runway surface. Further information on the guidelines, procedures, and performance specifications for Continuous Friction Measurement Equipment (CFME), may be found in FAA Advisory Circular 150/5320-12C, titled "Measurement, Construction and Maintenance of Skid Resistant Airport Pavement Surfaces." The certification procedures are conducted on a variety of textured surfaces in order to assure repeatability and correlation. This certification process is used for FAA correlation testing prior to qualifying equipment for Airport Improvement Program (AIP) funding. The correlation tests use the self-watering feature of the vehicles, which apply a thin film of water (0.04in. or1mm), directly in front of the measurement tire to simulate rain wet conditions.
One of the four surfaces utilized to develop the data is comprised of aluminum panels to simulate a low texture surface. The wet aluminum panels produce a surface with an average coefficient of friction (mu) below 0.10. All of the approved friction measuring devices correlate well at both 40 and 60 mph on the aluminum panels. Although this system works well when the CFME's are utilized for maintenance surveys, the self-watering feature of the vehicle is not used for winter operations. With the introduction of new friction devices to the international aviation community and the increased pressure on airports for more accurate field condition reports, the need to examine the correlation of the FAA approved devices during winter operations has become necessary.
The specific goals of the FAA's Airport Technology R & D Branch are: 1) to study the feasibility of expanding the limitations on the use of the Continuous Friction Measurement Equipment (CFME) during winter operations, and 2) to examine the correlation of the approved friction measurement devices during winter operations.
FAA's Dynatest Friction Test Vehicle on winter contaminated test bed
FAA's Saab Friction Test Vehicle on winter contaminated test be
These research efforts are being conducted in cooperation with the Joint Winter Runway Friction Test Program. The overall program is a joint effort with Transport Canada and NASA and focuses on advancing safe operations of aircraft when winter contaminates are present on the runway surface.
The joint effort is carefully examining the interface between aircraft braking performance and reported friction data to accurately predict the aircraft stopping distance requirements on winter contaminated surfaces. The two specific objectives of the Airport Technology R & D Branch, Airport R&D, are connected with the joint program objectives. The cooperative effort allows sharing of data and leveraging of resources to further understand the complexities involved with accurate measurement and reporting procedures for winter contaminated runways. The Joint Winter Runway Friction Test Program is a series of agreements with a five-year life span. Three years of testing at Jack Garland International Airport in North Bay, Ontario, Canada has provided a wealth of data which is under review by experts from industry and government. Preliminary analysis has been completed, with reports from the lead agencies expected shortly. The American Society for Testing and Materials (ASTM) E-17 Committee has established a series of sub-committees to consolidate the standardization process. The testing protocol for this winter has been established and is currently under review.
FAA's B-727 aircraft on winter contaminated test bed
Transport Canada's Falcon 20 aircraft on winter contaminated test bed
"An Evaluation of Winter Operational Runway Friction Measurement Equipment, Procedures, and Research", submitted by the Winter Runway Friction Measurement and Reporting Working Group, January, 1995
TP 12584E, "Aircraft tire braking friction under winter conditions: laboratory testing", Fleet Technology Ltd., 1996
TP 12943, "Proceedings of the international meeting on aircraft performance on contaminated runways/Compte rendu de la Réunion internationale sur la performance des avions utilisant despistes chargées de contaminants", TDC, 1996
Contact Project Lead: Nick Subbotin, ANG-E261
Other points of contact:
Tom Yager NASA Langley Research Center
Angelo Boccanfuso Transportation Development Center
Last Update: 04/02/12