U.S. Department 

of Transportation 

Federal Aviation 

Administration 

Advisory 

Circular

Subject: Change 1 to MEASUREMENT, 

CONSTRUCTION, AND MAINTENANCE OF SKIDRESISTANT AIRPORT PAVEMENT SURFACES 

Date: 04/16/04

Initiated by: AAS-100 

AC No: 150/5320-12C

Change: 1 

1. PURPOSE. This change updates information regarding FAA qualified Continuous Friction Measuring Equipment. 

2. PRINCIPAL CHANGES. The following editorial changes have been made: 

 a. Table 3-2. Friction Level Classification For Runway Pavement Surfaces revised to change name from 

K.J. Law Runway Friction Tester to Dynatest Consulting, Inc., Runway Friction Tester. 

b. Appendix 4. FAA-Approved CFME revised to change name from K.J. Law Engineers, Inc., to 

Dynatest Consulting, Inc., which includes their address. 

c. Appendix 4. Changes have been made to reflect updated information for manufacturers. 

PAGE CONTROL CHART

Remove Pages Dated Insert Pages Dated 

22 3/18/97 22 4/16/04 

Appendix 4 

pg. 1 (and 2)

3/18/97 Appendix 4 

pg. 1 (and 2) 

4/16/04 

DAVID L. BENNETT 

Director, Office of Airport Safety and Standards 

3/18/97 AC 150/5320-12C 

21 

CFME furnished with self-wetting systems should be 

calibrated periodically to assure that the water flow 

rate is correct and that the amount of water produced 

for the required water depth is consistent and applied 

evenly in front of the friction measuring wheel(s) for 

all test speeds. 

Section 3. Conducting Friction Evaluations with CFME 

3-14. PRELIMINARY STEPS. Friction 

measurement operations should be preceded by a 

thorough visual inspection of the pavement to identify 

deficiencies as outlined in paragraph 3-4. Careful and 

complete notes should be taken not only of the CFME 

data but of the visual inspection as well. The airport 

operator should assure that appropriate 

communications equipment and frequencies are 

provided on all vehicles used in conducting friction 

surveys and that all personnel are fully cognizant of 

airport safety procedures. Personnel operating the 

equipment should be fully trained and current in all 

procedures. The CFME should be checked for 

accurate calibration and the vehicle checked for 

adequate braking ability. 

3-15. LOCATION OF FRICTION SURVEYS ON 

THE RUNWAY. The airport operator, when 

conducting friction surveys on runways at 40 mph (65 

km/h), should begin recording the data 500 feet (152 

m) from the threshold end to allow for adequate 

acceleration distance. The friction survey should be 

terminated approximately 500 feet (152 m) from the 

opposite end of the runway to allow for adequate 

distance to safely decelerate the vehicle. When 

conducting friction surveys at 60 mph (95 km/h), the 

airport operator should start recording the survey 

1,000 feet (305 km) from the threshold end and 

terminate the survey approximately 1,000 feet from 

the opposite end of the runway. Where travel beyond 

the end of the runway could result in equipment 

damage or personal injury, additional runway length 

should be allowed for stopping. The lateral location on 

the runway for performing the test is based on the type 

of aircraft operating on the runway. Unless surface 

conditions are noticeably different on either side of the 

runway centerline, a test on one side of the centerline 

in the same direction the aircraft lands should be 

sufficient. However, when both runway ends are to be 

evaluated, vehicle runs can be made to record data on 

the return trip (both ways). 

The lateral location on the runway for performing 

friction surveys is based on the type and/or mix of 

aircraft operating on the runway: 

a. Runways Serving Only Narrow Body Aircraft.

Friction surveys should be conducted 10 feet (3 m) to 

the right of the runway centerline 

b. Runways Serving Narrow Body and Wide Body 

Aircraft. Friction surveys should be conducted 10 and 

20 feet (3 and 6 m) to the right of the runway 

centerline to determine the worst case condition. If the 

worst case condition is found to be consistently 

limited to one track, future surveys may be limited to 

this track. Care should be exercised, however, to 

account for any future and/or seasonal changes in 

aircraft mix. 

3-16. VEHICLE SPEED FOR CONDUCTING 

SURVEYS. All of the approved CFME in Appendix 4 

can be used at either 40 mph (65 km/h) or 60 mph (95 

km/h). The lower speed determines the overall 

macrotexture/contaminant/drainage condition of the 

pavement surface. The higher speed provides an 

indication of the condition of the surface's 

microtexture. A complete survey should include tests 

at both speeds. 

3-17. USE OF CFME SELF-WETTING SYSTEM. 

Since wet pavement always yields the lowest friction 

measurements, CFME should routinely be used on wet 

pavement which gives the "worst case" condition. 

CFME is equipped with a self-wetting system to 

simulate rain wet pavement surface conditions and 

provide the operator with a continuous record of 

friction values along the length of the runway. The 

attached nozzle(s) are designed to provide a uniform 

water depth of 1 mm (0.04 inch) in front of the friction 

measuring tire(s). This wetted surface produces 

friction values that are most meaningful in 

determining whether or not corrective action is 

required. 

3-18. FRICTION SURVEYS DURING RAINFALL. 

One limitation in using the self-wetting system on a 

friction measuring device is that it cannot by itself 

indicate the potential for hydroplaning. Some runways 

have depressed areas which pond during periods of 

moderate to heavy rainfall. These areas may exceed 

considerably the water depth used by the self-wetting 

system of the friction measuring device. Therefore, it 
AC 150/5320-12C, Change 1 4/16/04 

22 

is recommended that the airport owner periodically 

conduct visual checks of the runway surface during 

rainfall, noting the location, average water depth, and 

approximate dimensions of the ponded areas. If the 

average water depth exceeds 1/8 inch (3 mm) over a 

longitudinal distance of 500 feet (152 m), the 

depressed area should be corrected to the standard 

transverse slope. If possible, the airport owner should 

conduct periodic friction surveys during rainfall 

through the ponded areas. 

3-19. FRICTION LEVEL CLASSIFICATION. Mu 

numbers (friction values) measured by CFME can be 

used as guidelines for evaluating the surface friction 

deterioration of runway pavements and for identifying 

appropriate corrective actions required for safe aircraft 

operations. Table 3-2 depicts the friction values for 

three classification levels for FAA qualified CFME 

operated at 40 and 60 mph (65 and 95 km/h) test 

speeds. This table was developed from qualification 

and correlation tests conducted at NASA’s Wallops 

Flight Facility in 1989. 

TABLE 3-2. FRICTION LEVEL CLASSIFICATION FOR RUNWAY PAVEMENT SURFACES 

40 mph 60 mph 

Minimum 

Maintenance 

Planning 

New 

Design/ 

Construction Minimum 

Maintenance 

Planning 

New 

Design/ 

Construction

Mu Meter .42 .52 .72 .26 .38 .66 

Dynatest Consulting, Inc. 

Runway Friction Tester 

.50 .60 .82 .41 .54 .72 

Airport Equipment Co. 

Skiddometer 

.50 .60 .82 .34 .47 .74 

Airport Surface Friction Tester .50 .60 .82 .34 .47 .74 

Airport Technology USA 

Safegate Friction Tester 

.50 .60 .82 .34 .47 .74 

Findlay, Irvine, Ltd. Griptester 

Friction Meter 

.43 .53 .74 .24 .36 .64 

Tatra Friction Tester .48 .57 .76 .42 .52 .67 

Norsemeter RUNAR (operated 

at fixed 16% slip) 

.45 .52 .69 .32 .42 .63 

3-20. EVALUATION AND MAINTENANCE 

GUIDELINES. The following evaluation and 

maintenance guidelines are recommended based on 

the friction levels classified in Table 3-2. These 

guidelines take into account that poor friction 

conditions for short distances on the runway do not 

pose a safety problem to aircraft, but long stretches of 

slippery pavement are of serious concern and require 

prompt remedial action. 

a. Friction Deterioration Below the 

Maintenance Planning Friction Level (500 ft). 

When the average Mu value on the wet runway 

pavement surface is less than the Maintenance 

Planning Friction Level but above the Minimum 

Friction Level in Table 3-2 for a distance of 500 feet 

(152 m), and the adjacent 500 foot (152 m) segments 

are at or above the Maintenance Planning Friction 

Level, no corrective action is required. These readings 

indicate that the pavement friction is deteriorating but 

the situation is still within an acceptable overall 

condition. The airport operator should monitor the 

situation closely by conducting periodic friction 

surveys to establish the rate and extent of the friction 

deterioration. 
4/16/04 AC 150/5320-12C, Change 1 

 Appendix 4 

 1 (and 2) 

APPENDIX 4. FAA-APPROVED CFME 

AIRPORT SURFACE FRICTION TESTER INDUSTRIES AB AIRPORT SURFACE FRICTION TESTER 

Metallgatan 7 +46 0 411 651 00 

271 39 Ystad, Sweden FAX +46 0 411 190 12 

SWEDEN sales@ asft.se 

AIRPORT TECHNOLOGY USA SAFEGATE FRICTION TESTER 

NO LONGER AVAILABLE 

DYNATEST CONSULTING, INC., RUNWAY FRICTION TESTER (M6800) 

(FORMERLY K.J. LAW ENGINEERS, INC.) (904) 964-3777

13952 US Highway 301 South FAX (904) 964-3749 

Starke, FL 32091 

FINDLAY, IRVINE, LTD. GRIPTESTER FRICTION TESTER

42-44 Bog Road, Penicuik +44 1968 672111 

Midlothian EH 26 9 BU FAX +44 1968 671237 

SCOTLAND www.findlayirvine.com 

INTERTECH ENGINEERING TATRA FRICTION TESTER

 NO LONGER AVAILABLE 

NEUBERT AERO CORP. MARK 4 MU METER 

4105 West DeLeon Street (404) 252-0600 

Tampa, FL 33609 FAX (727) 789-2015 

 www.airportnac.com 

NORSEMETER RUNAR RUNWAY ANALYSER AND RECORDER 

P.O. Box 125 +47 23 20 1270 

Bogstadvien FAX + 47 23 20 1271 

0323 0310 

NORWAY 

PATRIA VAMMAS AEC BV-11 SKIDDOMETER 

P.O. Box 18 Vammaksentie + 358 20 4694041 

FIN-38201 Vammala FAX +358 20 4694250 

FINLAND www.patria.fi