U.S. Department

of Transportation

Federal Aviation

Administration

Advisory

Circular

Subject: MEASUREMENT, CONSTRUCTION, AND

MAINTENANCE OF SKID-RESISTANT AIRPORT

PAVEMENT SURFACES

Date: 3/18/97

Initiated by: AAS-100

AC No: 150/5320-12C

Change:

1. PURPOSE. This advisory circular (AC)

contains guidelines and procedures for the design and

construction of skid-resistant pavement, pavement

evaluation with friction measuring equipment, and

maintenance of high skid-resistant pavements.

2. CANCELLATION. AC 150/5320-12B,

Measurement, Construction, and Maintenance of SkidResistant Airport Pavement Surfaces, dated November

12, 1991, is canceled.

3. RELATED READING MATERIAL.

Appendix 2 contains a listing of documents containing

supplemental material relating to the subject.

Information on ordering these documents is also

provided.

4. APPLICATION. The guidelines and standards

contained herein are recommended by the Federal

Aviation Administration (FAA) for applications

involving runway friction measurement, construction,

and maintenance. For airport projects funded under

Federal grant assistance programs, the standards

identified by BOLDFACE CAPITALS in chapter 2,

section 4, paragraphs 2-21 and 2-22 and those in

appendix 3 are mandatory.

5. BACKGROUND. With the introduction of

turbojet aircraft, braking performance on pavement

surfaces has become more critical. Under certain

conditions, hydroplaning or unacceptable loss of

traction can occur, resulting in poor braking

performance and possible loss of directional control.

To address this concern, a number of research projects

were conducted by the National Aeronautics and Space

Administration (NASA), FAA, United States Air Force

(USAF), and various foreign governments. These

efforts concentrated in two major areas: (a) high skidresistant pavement surface design and evaluation and

(b) application of proper maintenance techniques and

procedures. In this circular, guidelines are provided to

airport operators on how to locate and restore areas on

the pavement surface where friction has deteriorated

below acceptable levels for aircraft braking

performance. The material contained in this circular

summarizes the findings of these research efforts.

6. METRIC UNITS. To promote an orderly

transition to metric (SI) units, this circular contains

both English and metric dimensions. The metric

conversions may not be exact equivalents and, until

there is an official changeover to the metric system, the

English dimensions will govern.

DAVID L. BENNETT

Director, Office of Airport Safety and Standards

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

iii

CONTENTS

Paragraph Page

CHAPTER 1. OVERVIEW

1-1. Purpose................................................................................................................................................................. 1

1-2. Background .......................................................................................................................................................... 1

1-3. Pavement Design Research................................................................................................................................... 1

1-4. Pavement Maintenance and Evaluation Research.................................................................................................. 1

1-5. Friction Measuring Equipment Research .............................................................................................................. 2

1-6. Additional Background and Information............................................................................................................... 2

CHAPTER 2. DESIGN AND CONSTRUCTION OF SKID-RESISTANT PAVEMENT

Section 1. Basic Design Considerations

2-1. General................................................................................................................................................................. 3

2-2. Surface Texture and Drainage .............................................................................................................................. 3

2-3. Painted Areas On Pavement Surfaces.................................................................................................................... 3

Section 2. Hot-Mix Asphalt (HMA) Pavement

2-4. Construction Techniques for HMA Pavement ....................................................................................................... 3

2-5. HMA Pavement Mixtures..................................................................................................................................... 3

2-6. Porous Friction Course (PFC)............................................................................................................................... 4

2-7. Chip Seals............................................................................................................................................................ 5

2-8. Aggregate Slurry Seal........................................................................................................................................... 5

Section 3. Portland Cement Concrete (PCC) Pavement

2-9. Construction Techniques for PCC Pavement......................................................................................................... 5

2-10.Timing and Curing............................................................................................................................................... 5

2-11.Brush or Broom Finish ......................................................................................................................................... 5

2-12.Burlap Drag Finish............................................................................................................................................... 5

2-13.Wire Combing...................................................................................................................................................... 5

2-14.Wire Tined ........................................................................................................................................................... 6

Section 4. Runway Grooving

2-15. General Grooving Techniques .............................................................................................................................. 6

2-16. Determining Need for Grooving ........................................................................................................................... 6

2-17. Suitability of Existing Pavements for Grooving..................................................................................................... 6

2-18. Overlays............................................................................................................................................................... 7

2-19. HMA Pavement Grooving .................................................................................................................................... 7

2-20. PCC Pavement Grooving...................................................................................................................................... 7

2-21. FAA Specifications for Runway Grooving ............................................................................................................ 7

2-22. Grooving Runway Intersections and Angled Exit Taxiways.................................................................................. 8
AC 150/5320-12C 3/18/97

Page

iv

CHAPTER 3. PAVEMENT EVALUATION

Section 1. Need for and Frequency of Evaluation

3-1. Friction Deterioration..........................................................................................................................................19

3-2. Scheduling Pavement Evaluations.......................................................................................................................19

3-3. Minimum Friction Survey Frequency ..................................................................................................................19

3-4. Surveys Without Continuous Friction Measuring Equipment (CFME).................................................................19

3-5. Groove Deterioration...........................................................................................................................................20

3-6. Measurement of Pavement Surface Texture.........................................................................................................20

Section 2. CFME - General

3-7. General Requirements for CFME........................................................................................................................20

3-8. FAA Performance Standards for CFME ..............................................................................................................20

3-9. FAA Qualified Product List.................................................................................................................................20

3-10. Use of Decelerometer..........................................................................................................................................20

3-11. Federal Funding of CFME ..................................................................................................................................20

3-12.Training of Personnel..........................................................................................................................................20

3-13.Calibration..........................................................................................................................................................20

Section 3. Conducting Friction Evaluation with CFME

3-14. Preliminary Steps................................................................................................................................................21

3-15.Location of Friction Surveys on the Runway........................................................................................................21

3-16. Vehicle Speed for Conducting Surveys................................................................................................................21

3-17. Use of CFME Self-Wetting System .....................................................................................................................21

3-18. Friction Surveys During Rainfall.........................................................................................................................21

3-19. Friction Level Classification................................................................................................................................22

3-20.Evaluation and Maintenance Guidelines .............................................................................................................22

3-21.Computer Evaluation of Friction Test Data .........................................................................................................23

Section 4. Conducting Texture Depth Measurements

3-22.Recommended Testing........................................................................................................................................23

3-23 Recommended Texture Depth .............................................................................................................................23

3-24.Location Of Measurements..................................................................................................................................23

3-25.Test Methods ......................................................................................................................................................23

3-26.Computation .......................................................................................................................................................24

CHAPTER 4. MAINTAINING HIGH SKID-RESISTANCE

Section 1. Maintenance Considerations

4-1. Need for Maintenance .........................................................................................................................................28

Section 2. Methods for Removing Contaminants

4-2. Recommended Contaminant Removal Techniques..............................................................................................28
3/18/97 AC 150/5320-12C

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v

APPENDICES

Appendix 1. Qualification Process for CFME (1 page)

Appendix 2. Related Reading Material (2 pages)

Appendix 3. Performance Specifications for CFME (2 pages)

Appendix 4. FAA-Approved CFME (1 page)

Appendix 5. Training Requirements Outline for CFME (1 page)

FIGURES

Figure 2-1 Edge View of PFC Overlay ....................................................................................................................... 9

Figure 2-2 Aggregate Slurry Seal............................................................................................................................. 10

Figure 2-3 Heavy Paving Broom Finish ................................................................................................................... 11

Figure 2-4 Heavy Burlap Drag Finish ...................................................................................................................... 11

Figure 2-5 Wire Comb Technique Constructed at Patrick Henry Airport, Virginia,

Using a 1/8 " x 1/8 " x 1/2" Configuration .............................................................................................. 12

Figure 2-6 Sawed Grooves in HMA Pavement ......................................................................................................... 13

Figure 2-7 Sawed Grooves in PCC Pavement........................................................................................................... 13

Figure 2-8 Plastic Grooving Technique Using a Vibrating Ribbed Plate................................................................... 14

Figure 2-9 Plastic Grooving Technique Using a Ribbed Roller Tube ........................................................................ 15

Figure 2-10 Grooving Intersections of Primary and Secondary Runways.................................................................... 16

Figure 2-11 Grooving High Speed or Angled Exit Taxiways...................................................................................... 17

Figure 3-1 Grease-Volume Measuring Tube, Plunger, and Rubber Squeegee............................................................ 25

Figure 3-2 Measuring Tube Dimensions to Measure One Cubic Inch or Fifteen Cubic Centimeters.......................... 26

Figure 3-3 Measuring Tube Filled with Grease ........................................................................................................ 27

Figure 3-4 Illustration of Apparatus Used in Grease Application Technique For

Measuring Pavement Surface Texture Depth........................................................................................... 28

TABLES

Table 3-1 Friction Survey Frequency ...................................................................................................................... 19

Table 3-2 Friction Level Classification for Runway Pavement Surfaces .................................................................. 22

Table 4-1 Rubber Deposit Removal Frequency........................................................................................................ 29

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

1

CHAPTER 1. OVERVIEW

1-1. PURPOSE. This AC provides guidelines for

designing, constructing, and maintaining skid-resistant

airport pavement surfaces and for conducting

evaluations and surveys of runway friction for

pavement maintenance purposes. It also contains

performance specifications for friction measuring

equipment. Guidance on pavement friction

measurement for aircraft operational purposes during

winter weather and performance standards for

decelerometers are found in AC 150/5200-30, Airport

Winter Safety and Operations.

1-2. BACKGROUND. Since the advent of turbojet

aircraft with their greater weight and high landing

speeds, braking performance on runway surfaces,

particularly when wet, has become a significant safety

consideration. A number of research programs by

FAA, NASA, and USAF, as well as those performed by

foreign governments, have been directed in two major

areas: original pavement surface design to maximize

skid-resistance with proper materials and construction

techniques and effective evaluation and maintenance

techniques to detect deterioration of skid-resistance and

to restore it to acceptable levels.

1-3. PAVEMENT DESIGN RESEARCH.

Pavement grooving was the first major step in

achieving safer pavement surfaces for aircraft

operations in wet weather conditions. These studies

were completed by NASA at the Langley Research

Center, Langley, Virginia, in 1968. The FAA, through

its Technical Center in Atlantic City, New Jersey,

directed a test program on pavement surface treatments

at the Naval Air Engineering Center, Lakehurst, New

Jersey. The study was completed in 1983. Both the

NASA Langley and the FAA Technical Center studies

showed that a high level of friction could be achieved

on wet pavement by forming or cutting closely spaced

transverse grooves on the runway surface, which would

allow rain water to escape from beneath tires of

landing aircraft. Other research conducted both in the

United Kingdom and the United States determined that

an open graded, thin hot-mix asphalt (HMA) surface

course called "porous friction course" (PFC) also could

achieve good results. This permits rain water to

permeate through the course and drain off transversely

to the side of the runway, preventing water buildup on

the surface and creating a relatively dry pavement

condition during rainfall. The FAA Technical Center

study demonstrated that a high level of friction was

maintained on PFC overlays for the entire runway

length.

In addition, a number of studies were carried out, and

are continuing, on basic skid-resistant behaviors of

pavement surfaces, both HMA and Portland cement

concrete (PCC). These have led to other noteworthy

surface treatments that improve pavement surface

texture such as asphaltic chip and aggregate slurry

seals. For concrete pavements, wire combing the

surface, while the concrete is still in the plastic

condition, notably improves pavement surface texture.

1-4. PAVEMENT MAINTENANCE AND

EVALUATION RESEARCH. Regardless of

pavement type or surface treatment, runway friction

characteristics will change over time depending on

type and frequency of aircraft activity, weather,

environmental issues, and other factors. In addition to

ordinary mechanical wear and tear from aircraft tires,

contaminants can collect on runway pavement surfaces

to decrease their friction properties. Contaminants such

as rubber deposits, dust particles, jet fuel, oil spillage,

water, snow, ice, and slush all cause friction loss on

runway pavement surfaces. Rubber deposits occur in

the touchdown areas on runways and can be quite

extensive. Heavy rubber deposits can completely cover

the pavement surface texture thereby causing loss of

aircraft braking capability and directional control when

runways are wet.

In October 1978, the FAA embarked on a 2-year

program to conduct friction and pavement evaluation

surveys at 268 airports (491 runways) within the

contiguous United States. The information obtained

represented a very broad collection of data on the

friction characteristics of runways at airports that have

turbojet aircraft operations. Field observations of the

runway pavement surface conditions and analysis of

the friction test data identified those areas on the

runway pavement which were below the minimum

acceptable friction level. Test data and surface

condition information obtained during this program

were given to airport owners so that they could take

proper corrective measures to eliminate runway

pavement deficiencies.
AC 150/5320-12C 3/18/97

2

1-5. FRICTION MEASURING EQUIPMENT

RESEARCH. Beginning in the early 1970's, NASA,

FAA, and USAF conducted runway traction studies to

determine the correlation between various types of

aircraft and friction measuring equipment. These

studies showed a fair correlation between some of the

friction measuring devices, but the tests on correlation

between the friction devices and aircraft were

inconclusive. The tests did show, however, that friction

measuring devices were effective when used to evaluate

pavement surface friction properties for engineering

and maintenance purposes.

In March of 1990, FAA concluded a test program to

evaluate the performance of different tires on approved

friction measuring devices and to develop correlation

data in order to ensure that devices of different

manufacture and design would give comparable results

in field use. Appendix 1 summarizes research on

qualification and correlation of friction measuring

equipment.

1-6. ADDITIONAL BACKGROUND AND

INFORMATION. Appendix 2 contains a list of

pertinent reading material on design and evaluation of

skid-resistant pavements.
3/18/97 AC 150/5320-12C

3

CHAPTER 2. DESIGN AND CONSTRUCTION OF SKID-RESISTANT PAVEMENT

Section 1. Basic Design Considerations

2-1. GENERAL. In building new runways, major

reconstruction, or adding overlays, the design engineer

must choose either HMA or PCC as the basic paving

component. The selection is usually based on

economics, local preference, and other design factors.

These considerations, as well as basic pavement

structural design, are covered in AC 150/5320-6,

Airport Pavement Design and Evaluation. This chapter

is limited to discussion only of the surface of the

airport pavement, literally "where the rubber meets the

runway." All of the techniques discussed in this

chapter may be applied during original construction (or

reconstruction), and some may be applied to existing

pavement to restore or create good friction

characteristics.

2-2. SURFACE TEXTURE AND DRAINAGE. In

discussing the effects of pavement texture on friction

and hydroplaning, two terms commonly used to

describe the pavement surface are microtexture and

macrotexture. Microtexture refers to the fine scale

roughness contributed by small individual aggregate

particles on pavement surfaces which are not readily

discernible to the eye but are apparent to the touch, i.e.,

the feel of fine sandpaper. Macrotexture refers to

visible roughness of the pavement surface as a whole.

Microtexture provides frictional properties for aircraft

operating at low speeds and macrotexture provides

frictional properties for aircraft operating at high

speeds. Together they provide adequate frictional

properties for aircraft throughout their landing/takeoff

speed range.

The primary function of macrotexture is to provide

paths for water to escape from beneath the aircraft

tires. This drainage property becomes more important

as the aircraft speed increases, tire tread depth

decreases, and water depth increases. All three of these

factors contribute to hydroplaning. Good microtexture

provides a degree of "sharpness" necessary for the tire

to break through the residual water film that remains

after the bulk water has run off. Both properties are

essential in providing skid-resistant pavement surfaces.

Textural appearances, however, can be deceiving. A

rough looking surface could provide adequate drainage

channels for the water to escape, but the fine aggregate

in the pavement may consist of rounded or uncrushed

mineral grains that are subject to polishing by traffic,

thereby causing the pavement surface to become

slippery when wet. Likewise, a less rough looking

surface, that may even have a shiny appearance when

wet, will not necessarily be slippery if it has good

microtextural properties.

All paving should, of course, be constructed with

appropriate transverse slope for basic drainage and

must have adequate provision for prompt removal of

storm runoff. AC 150/5300-13, Airport Design,

provides guidance in this area.

2-3. PAINTED AREAS ON PAVEMENT

SURFACES. Painted areas of wet runway pavement

surfaces can be very slippery. In addition, an aircraft

with one main gear on a painted surface, and the other

on an unpainted surface, may experience differential

braking. It is important to keep the skid-resistance

properties of painted surfaces as close to that of

unpainted surfaces as possible. Usually this means

adding a small amount of silica sand to the paint mix

to increase the friction properties of the painted

surface. Glass beads, while used primarily to increase

conspicuity of markings, have been shown to increase

friction levels, also.

Section 2. Hot-Mix Asphalt (HMA) Pavement

2-4. CONSTRUCTION TECHNIQUES FOR

HMA PAVEMENT. The surface texture of newly

constructed HMA pavements is usually quite smooth.

This is due to the rolling done during construction to

achieve the required compaction and density.

Nevertheless, several methods are available to improve

surface texture and friction in HMA pavements. These

include proper mix design and the use of PFCs, chip

seals, and aggregate slurry seals. Saw cut grooves

made after final compaction are highly effective. This

chapter gives guidance for providing these surface

treatments. The construction specification for HMA

pavement is contained in AC 150/5370-10, Standards

for Specifying Construction of Airports.

2-5. HMA PAVEMENT MIXTURES. Several

factors concern the pavement designer in selecting the

appropriate design mix. These factors include the
AC 150/5320-12C 3/18/97

4

blending of aggregate sources, aggregate size and

gradation, the relationship between aggregates and

binder, and the construction methods to obtain the

required surface properties which meet all other

requirements.

a. Blending Aggregates. When superior

quality aggregates are in limited supply or processing

costs are prohibitive, natural aggregates can be

combined with synthetic aggregates.

b. Aggregate Size and Gradation. The

maximum size aggregate, as well as the mix gradation,

may be varied by the pavement designer to produce the

desired surface texture and strength. For HMA

pavement, the size and properties of the coarse

aggregate are critical for good macrotexture.

Generally, the larger size aggregates in HMA

pavement mixtures provide greater skid-resistance than

the smaller ones.

c. Aggregate Characteristics. After size and

gradation, the most frequently considered

characteristics for skid-resistant aggregates are

resistance to polish and wear, texture, and shape of

particles.

(1) Resistance to Polish and Wear. The

ability of an aggregate to resist the polish and wear

action of aircraft traffic has long been recognized as

the most important characteristic. Certain aggregates

in pavements are more susceptible to wear and polish

effects than others, becoming extremely slippery when

wet. The presence of coarse grain sizes and gross

differences in grain hardness appear to combine and

lead to differential wear and breaking off of grains

resulting in a constantly renewed abrasive surface.

Rocks high in silica content are the most satisfactory

performers. Generally, high carbonate rocks are poor

performers. Rocks that are generally acceptable are

unweathered crushed quartzite, quartz diorite,

granodiorite, and granite.

(2) Texture. The surface textures of

individual aggregates are governed by the size of the

individual mineral grains and the matrix in which they

are cemented. For an aggregate to exhibit satisfactory

skid-resistant properties, it should contain at least two

mineral constituents of different hardness cemented in

a matrix that will wear differentially, thus continually

exposing new surfaces.

(3) Shape. The shape of an aggregate

particle, which is determined by crushing, significantly

affects its skid-resistant properties. Aggregate shape

depends on many of the same factors that influence

texture. The angularity of an aggregate contributes to

its skid-resistant quality. Flat, elongated particles are

poor performers.

d. Asphalt Cement. The characteristics and

percentages of the asphalt cement used should be in

accordance with standard HMA pavement design

practice.

2-6. PFC. One method used to improve runway

pavement skid-resistance and mitigate hydroplaning is

a thin HMA surface course overlay that ranges from

3/4 inch to 1-1/2 inches (25 mm to 40 mm) thick,

characterized by its open graded matrix.

a. Pavement Suitability for PFC. Prior to

constructing this type of surface course, the existing

pavement surface should be evaluated to determine its

structural integrity. Strengthening of the existing

pavement, if needed, should be accomplished before

laying the PFC. Also, the pavement should be in good

condition; that is, it should have proper longitudinal

and transverse grades and a watertight surface that is

free of major cracks, significant depressions, or any

other surface irregularities. For minor cracks, normal

maintenance procedures should be followed as given in

AC 150/5380-6, Guidelines and Procedures for

Maintenance of Airport Pavements. If there are rubber

deposits on the runway pavement surface, these areas

should be cleaned prior to constructing the PFC

overlay. The PFC should be constructed only on HMA

pavements. It has been shown that a longer life, as

well as better adhesion and bond, can be achieved by

adding rubber particles during the preparation of the

mix. The specification for the PFC is given in AC

150/5370-10. Figure 2-1 shows an edge view of a

typical PFC overlay.

b. Restrictions to PFC Construction. On PFC

constructed runway surfaces that have high aircraft

traffic operations, rubber accumulation can become a

serious problem if not closely monitored. If the rubber

deposits are not removed before they completely cover

the pavement surface and plug up the void spaces in

the matrix of the overlay, water can no longer drain

internally through the structure of the overlay. When

this condition occurs, it is impossible to remove the

rubber deposits without causing serious damage to the

structural integrity of the overlay. Therefore, the FAA
3/18/97 AC 150/5320-12C

5

recommends that PFC overlays not be constructed on

airport runways that have high aircraft traffic

operations (over 91 turbojet arrivals per day per

runway end).

2-7. CHIP SEAL. Temporary improvement of

surface friction can be achieved by constructing a chip

seal. Latex added to the chip seal extends its life and

provides better bond and adhesion to the existing

pavement surface. A fog seal added on top of the chip

seal will help minimize loose chips and prevent aircraft

damage.

2-8. AGGREGATE SLURRY SEAL. Temporary

improvement of skid-resistance for pavement surfaces

can be gained by constructing an aggregate slurry seal,

either gradation type II or type III, as given in the

specification in AC 150/5370-10. Aggregate slurry

seats are recommended only as an interim measure

until an overlay is constructed. This type of

construction is usually adequate for 2 to 5 years.

Figure 2-2 shows a typical type II aggregate slurry seal.

Experience has shown that slurry seals do not hold up

well in cold climates where snow removal occurs. A

life cycle cost analysis should be conducted to

determine the long term benefits.

Section 3. Portland Cement Concrete (PCC) Pavement

2-9. CONSTRUCTION TECHNIQUES FOR PCC

PAVEMENT. Several methods are available to the

paving contractor for constructing skid-resistant PCC

pavement surfaces. When PCC pavement is still in the

plastic condition, it is strongly recommended that some

type of textural finish be constructed in the pavement

surface prior to grooving. Such texturing can be

accomplished by using either a brush or broom finish

or a heavy burlap drag finish. Wire combed or wire

tined construction provides an excellent textural finish

to the surface. Also, plastic grooves can be constructed

in the pavement before it has hardened. For PCC

pavements that have hardened, grooves can be saw cut

in the pavement. The textural and grooving

construction techniques are briefly described in the

following paragraphs. The basic construction

specifications for PCC pavement are given in AC

150/5370-10. Quality concrete is a prerequisite to the

retention of pavement skid-resistance. The physical

properties of the fine aggregates and effectiveness of

curing are important factors in improving wear

resistance.

2-10.TIMING AND CURING. Timing in applying

the curing compound is as important as timing the

final finishing operations to assure long lasting,

nonskid pavement surface texture. The timing of the

texturing operation is critical because PCC pavements

rarely lose surface moisture evenly or set at a uniform

rate, especially during warm weather paving

operations. The best time to texture a PCC pavement

during construction is when the water spots have dried

enough to reasonably hold the texture but before the

drier spots have dried too much to texture at all. This

is one of the toughest decisions for the paving

contractor. After texturing of the pavement surface has

been completed, immediate application of the curing

compound assures that the pavement surface will not

lose water and cure too rapidly. If the pavement cures

too quickly, the ridges of mortar left by the finishing

technique will not set properly and their durability will

be greatly reduced, resulting in a faster rate of

diminishing skid-resistance. Therefore, extreme care

must be taken in this process to assure an effective

cure.

2-11.BRUSH OR BROOM FINISH. If the

pavement surface texture is to be a type of brush or

broom finish, it should be applied when the water

sheen has practically disappeared. The equipment

should operate transversely across the pavement

surface, providing corrugations that are uniform in

appearance and approximately 1/16 inch (1-1/2 mm)

deep. It is important that the texturing equipment not

tear or unduly roughen the pavement surface during

the operation. Any imperfections resulting from the

texturing operation should be corrected immediately

after application before the concrete becomes too stiff

to work. Figure 2-3 shows the texture formed by the

broom finish.

2-12.BURLAP DRAG FINISH. Burlap used to

texture the pavement surface should be at least

15 ounces/square yard (355 gm/square m). To produce

a rough textured surface, the transverse threads of the

burlap should be removed from approximately 1 foot

(0.3 m) of the trailing edge and grout should be

allowed to accumulate and harden on the trailing

burlap threads. A heavy buildup of grout on the burlap

threads produces the desired wide sweeping

longitudinal striations on the pavement surface. The

aggregate particles form the corrugations which should

be uniform in appearance and approximately 1/16 inch
AC 150/5320-12C 3/18/97

6

(1-1/2 mm) deep. A runway pavement constructed

with a burlap drag finish is shown in Figure 2-4.

2-13.WIRE COMBING. The wire comb technique

uses rigid steel wires to form a deep texture in the

plastic concrete pavement. An excellent example of

this method is the runway constructed at Patrick Henry

Airport in Virginia, where the spacing of the ridges is

approximately 1/2 inch (13 mm) center to center (see

Figure 2-5). The spring steel wires which were used

had an exposed length of 4 inches (100 mm), thickness

of 0.03 inch (0.7 mm), and width of 0.08 inch (2 mm).

The wire comb equipment should provide grooves that

are approximately 1/8 inch x 1/8 inch (3 mm x 3 mm)

spaced 1/2 inch (13 mm) center to center. It is not

necessary to provide preliminary texturing before

constructing the wire comb texture. Because of the

closeness of the spaced grooves, the preliminary

texturing of the remaining land areas would not be

effective. The wire comb technique should be

constructed over the full pavement width. This

technique is not to be confused with saw cut or

plastic grooved runway pavements. Wire combing is

a texturing technique and cannot be substituted for saw

cut or plastic grooves because it does not prevent

aircraft from hydroplaning.

2-14.WIRE TINING. Flexible steel wires are used to

form deep texture in the plastic concrete pavement.

The flexible steel bands are 5 inches (125 mm) long,

approximately 1/4 inch (6 mm) wide, and spaced

1/2 inch (13 mm) apart. The appearance of this

technique is quite similar to the wire comb method.

This technique is not to be confused with saw cut or

plastic grooved runway pavements. Wire tining is a

texturing technique and cannot be substituted for saw

cut or plastic grooved because it does not prevent

aircraft from hydroplaning.

Section 4. Runway Grooving

2-15.GENERAL GROOVING TECHNIQUES.

Cutting or forming grooves in existing or new

pavement is a proven and effective technique for

providing skid-resistance and prevention of

hydroplaning during wet weather. In existing

pavement (both HMA and PCC), grooves must be saw

cut; in new PCC pavement, grooves may be formed

while the concrete is still plastic. Grooves in HMA

pavement must be saw cut whether new or existing

pavement is to be treated.

2-16. DETERMINING NEED FOR GROOVING.

Grooving of all runways, serving or expected to serve

turbojet aircraft, is considered high priority safety work

and should be accomplished during initial

construction. Such existing runways without grooving

should be programmed as soon as practicable. For

other runways, the following factors should be

considered:

a. Historical review of aircraft accidents and

incidents related to hydroplaning at the airport.

b. Wetness frequency (review of annual rainfall

rates and intensity).

c. Transverse and longitudinal grades, flat

areas, depressions, mounds, or any other surface

abnormalities that may impede water runoff.

d. Surface texture quality as to slipperiness

under dry or wet conditions. Polishing of aggregate,

improper seat coating, inadequate micro-macrotexture,

and contaminant buildup are some examples of

conditions that may cause the loss of surface friction.

e. Terrain limitations such as dropoffs at the

ends of the runway safety areas.

f. Adequacy of number and length of available

runways.

g. Crosswind effects, particularly when low

friction factors prevail at the airport.

h. The strength and condition of the runway

pavements at the facility.

2-17. SUITABILITY OF EXISTING PAVEMENTS

FOR GROOVING. Existing pavements may have

surfaces that are not suitable for sawing grooves. A

survey should be conducted to determine if an overlay

or rehabilitation of the pavement surface is required

before grooving.

a. Reconnaissance. A thorough survey should

be made of the entire width and length of the runway.

Bumps, depressed areas, bad or faulted joints, and

badly cracked and/or spalled areas in the pavement

should not be grooved until such areas are adequately

repaired or replaced. To verify the structural condition
3/18/97 AC 150/5320-12C

7

of the pavement, tests should be taken in support of the

visual observations.

b. Tests. The strength and condition of the

runway pavement should be evaluated and tested

according to the procedures specified in ACs

150/5320-6 and 150/5370-10. Future aircraft loads

and activity levels should be considered when making

the evaluation. Core samples should be taken in HMA

pavement to determine stability. The American

Society for Testing and Materials (ASTM) Standard D

1559, Standard Test Method for Resistance to Plastic

Flow of Bituminous Mixtures Using Marshall

Apparatus, provides methods for testing the resistance

to plastic flow of HMA pavements. Engineering

judgment should be exercised when employing these

methods in determining the stability readings. These

tests are recommended to be used for guidance only.

Other factors should be considered in determining how

long grooves will remain effective in HMA pavements,

such as maximum operational pavement surface

temperature, effective tire pressure, frequency of

braking action in given areas, mix composition, and

aggregate properties. If, in the judgment of the person

evaluating the existing pavement, any of the above

conditions are not met, the pavement should not be

grooved.

2-18.OVERLAYS. If the evaluation shows that the

existing pavement is not suitable either because of

surface defects or from a strength standpoint, an

overlay, flexible or rigid, will be required. The new

overlay may then be grooved according to the

instructions given in the following paragraphs:

2-19.HMA PAVEMENT GROOVING.

Construction specifications for grooving are given in

paragraph 2-21. Grooving should not commence until

the HMA pavement has sufficiently cured to prevent

displacement of the aggregate (usually 30 days).

Figure 2-6 shows a saw-grooved HMA pavement

surface.

2-20.PCC Pavement Grooving. There are two

acceptable methods for grooving PCC pavements:

plastic grooving and saw cut grooving.

a. Plastic Grooving.

(1) Vibrating Ribbed Plate. One method to

form grooves in the concrete while in the plastic state

uses a vibrating ribbed plate attached to the bridge that

spans across the pavement slab. The plate is vibrated

to help redistribute the aggregate in the concrete. This

prevents tearing and shearing as the plate proceeds

transversely across the pavement slab. The grooves

formed in the pavement are approximately 1/4 inch x

1/4 inch (6 mm x 6 mm) width and depth, spaced

1-1/2 inch (40 mm) center to center. Figure 2-8 shows

the grooving operations.

(2) Ribbed Roller. Another method uses a

roller with protrusions or ribs which form the grooves

in the plastic concrete. This method does not give the

same finish as the method using the vibrating ribbed

plate. The roller is not vibrated and, therefore, does

not consistently penetrate to the required depth of 1/4

inch (6 mm). Figure 2-9 shows the results of this

technique.

b. Saw Grooving. For existing or new PCC

pavements that have hardened, transverse grooves can

be saw cut in the pavement. The timing should be as

directed by the engineer. Construction specifications

for providing saw grooves in PCC pavements are given

in paragraph 2-21. Figure 2-7 shows a saw-grooved

PCC pavement surface.

2-21.FAA SPECIFICATIONS FOR RUNWAY

GROOVING.

a. THE FAA STANDARD GROOVE

CONFIGURATION IS 1/4 INCH (±1/16 INCH) IN

DEPTH BY 1/4 INCH (+1/16 INCH, -0 INCH) IN

WIDTH BY 1 1/2 INCH (- 1/8 INCH, + 0 INCH)

CENTER TO CENTER SPACING).

THE FAA STANDARD GROOVE

CONFIGURATION IN METRICS IS 6 MM

(±1.6 MM) IN DEPTH BY 6 MM (+1.6 MM, -0

MM) IN WIDTH BY 38 MM (- 3 MM, + 0 MM)

CENTER TO CENTER SPACING).

b. THE DEPTH OF 60 PERCENT OR

MORE OF THE GROOVES SHALL NOT BE

LESS THAN 1/4 INCH (6 MM).

c. THE GROOVES SHALL BE

CONTINUOUS FOR THE ENTIRE RUNWAY

LENGTH AND TRANSVERSE

(PERPENDICULAR) TO THE DIRECTION OF

AIRCRAFT LANDING AND TAKEOFF

OPERATIONS.

d. THE GROOVES SHALL BE

TERMINATED WITHIN 10 FEET (3 M) OF THE
AC 150/5320-12C 3/18/97

8

RUNWAY PAVEMENT EDGE TO ALLOW

ADEQUATE SPACE FOR OPERATION OF THE

GROOVING EQUIPMENT.

e. THE GROOVES SHALL NOT VARY

MORE THAN 3 INCHES (8 CM) IN ALIGNMENT

FOR 75 FEET (23 M) ALONG THE RUNWAY

LENGTH, ALLOWING FOR REALIGNMENT

EVERY 500 FEET (150 M) ALONG THE

RUNWAY LENGTH.

f. GROOVES SHALL NOT BE CLOSER

THAN 3 INCHES (8 CM) OR MORE THAN

9 INCHES (23 CM) FROM TRANSVERSE

JOINTS IN CONCRETE PAVEMENTS.

g. WHERE LIGHTING CABLES ARE

INSTALLED, GROOVING THROUGH

LONGITUDINAL OR DIAGONAL SAW KERFS

SHALL BE AVOIDED. Grooves may be continued

through longitudinal construction joints.

h. Extreme care must be exercised when

grooving near in-pavement light fixtures and

subsurface wiring. GROOVES SHALL BE SAWED

NO LESS THAN 6 INCHES (15 CM) AND NO

MORE THAN 18 INCHES (46 CM) FROM INPAVEMENT LIGHT FIXTURES.

i. Bidding should be based on the square yard

of the grooved area, using the two-dimensional method

of measure with no deduction for areas skipped next to

joints and fixtures as specified.

j. Clean-up is extremely important and should

be continuous throughout the grooving operations.

The waste material collected during the grooving

operation must be disposed of by flushing with water,

by sweeping, or by vacuuming. If waste material is

flushed, the specifications should stipulate the

following:

(1) Whether or not the airport owner or

contractor is responsible for furnishing water for cleanup operations.

(2) That the waste material should not be

flushed into the storm or sanitary sewer system.

(3) That the waste material should not be

allowed to drain onto the grass shoulders adjacent to

the runway or left on the runway surface. Failure to

remove the material from all paved and shoulder areas

can create conditions hazardous to aircraft operations.

2-22.GROOVING RUNWAY INTER-SECTIONS

AND ANGLED EXIT TAXIWAYS.

a. IN ALL CASES, THE ENTIRE LENGTH

OF THE PRIMARY RUNWAY WILL BE

GROOVED. THE SECONDARY RUNWAY

INTERSECTING THE PRIMARY RUNWAY

SHALL BE SAW CUT IN A STEP PATTERN AS

SHOWN IN FIGURE 2-10.

b. HIGH SPEED OR ANGLED EXIT

TAXIWAYS SHALL BE SAW CUT IN A STEP

PATTERN AS SHOWN IN FIGURE 2-11. Since

grooving machines vary in cutting width, it is

suggested that the step pattern width start at the

projecting pavement edge, not exceeding 40 inches

(102 cm) in width.
3/18/97 AC 150/5320-12C

9

FIGURE 2-1. EDGE VIEW OF PFC OVERLAY
AC 150/5320-12C 3/18/97

10

FIGURE 2-2. AGGREGATE SLURRY SEAL
3/18/97 AC 150/5320-12C

11

FIGURE 2-3. HEAVY PAVING BROOM FINISH

FIGURE 2-4. HEAVY BURLAP DRAG FINISH
AC 150/5320-12C 3/18/97

12

FIGURE 2-5. WIRE COMB TECHNIQUE CONSTRUCTED AT PATRICK HENRY AIRPORT, VIRGINIA,

USING A 1/8 INCH X 1/8 INCH X 1/2 INCH CONFIGURATION
3/18/97 AC 150/5320-12C

13

FIGURE 2-6. SAWED GROOVES IN HMA PAVEMENT

FIGURE 2-7. SAWED GROOVES IN PCC PAVEMENT
AC 150/5320-12C 3/18/97

14

FIGURE 2-8. PLASTIC GROOVING TECHNIQUE USING A VIBRATING RIBBED PLATE
3/18/97 AC 150/5320-12C

15

FIGURE 2-9. PLASTIC GROOVING TECHNIQUE USING A RIBBED ROLLER TUBE
AC 150/5320-12C 3/18/97

16

FIGURE 2-10. GROOVING INTERSECTIONS OF PRIMARY AND SECONDARY RUNWAYS
3/18/97 AC 150/5320-12C

17 (and 18)(

FIGURE 2-11. GROOVING OF HIGH SPEED OR ANGLED EXIT TAXIWAYS

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

19

CHAPTER 3. PAVEMENT EVALUATION

Section 1. Need for and Frequency of Evaluation

3-1. FRICTION DETERIORATION. Over time,

the skid-resistance of runway pavement deteriorates

due to a number of factors, the primary ones being

mechanical wear and polishing action from aircraft

tires rolling or braking on the pavement and the

accumulation of contaminants, chiefly rubber, on the

pavement surface. The effect of these two factors is

directly dependent upon the volume and type of aircraft

traffic. Other influences on the rate of deterioration

are local weather conditions, the type of pavement

(HMA or PCC), the materials used in original

construction, any subsequent surface treatment, and

airport maintenance practices.

Structural pavement failure such as rutting, raveling,

cracking, joint failure, settling, or other indicators of

distressed pavement can also contribute to runway

friction losses. Prompt repair of these problems should

be undertaken as appropriate. Guidance on corrective

action may be found in chapter 2 and AC 150/5380-6.

Contaminants, such as rubber deposits, dust particles,

jet fuel, oil spillage, water, snow, ice, and slush, all

cause friction loss on runway pavement surfaces.

Removal and runway treatment for snow, ice, and

slush are covered in AC 150/5200-30. The most

persistent contaminant problem is deposit of rubber

from tires of landing jet aircraft. Rubber deposits

occur at the touchdown areas on runways and can be

quite extensive. Heavy rubber deposits can completely

cover the pavement surface texture causing loss of

aircraft braking capability and directional control,

particularly when runways are wet.

3-2. SCHEDULING PAVEMENT

EVALUATIONS. The operator of any airport with

significant jet aircraft traffic should schedule periodic

friction evaluations of each runway that accommodates

jet aircraft. These evaluations should be carried out in

accordance with the procedures outlined in either

Section 2 or 3 of this chapter, depending upon the

availability to the airport operator of continuous

friction measuring equipment (CFME). Every runway

for jet aircraft should be evaluated at least once each

year. Depending on the volume and type (weight) of

traffic on the runways, evaluations will be needed more

frequently, with the most heavily used runways

needing evaluation as often as weekly, as rubber

deposits build up. Runway friction measurements take

time, and while tests are being conducted, the runway

will be unusable by aircraft. Since this testing is not

time critical, a period should be selected which

minimizes disruption of air traffic. Airport operations

management should work closely with air traffic

control, fixed base operations, and/or airlines.

3-3. MINIMUM FRICTION SURVEY

FREQUENCY. Table 3-1 should be used as guidance

for scheduling runway friction surveys. This table is

based on an average mix of turbojet aircraft operating

on any particular runway. Most aircraft landing on the

runway are narrow body, such as the DC-9, BAC-111,

B-727, B-737, etc. A few wide body aircraft were

included in the mix. When any runway end has

20 percent or more wide body aircraft (L-1011, B-747,

DC- 10, MD-11, C-5, etc.) of the total aircraft mix, it

is recommended that the airport operator should select

the next higher level of aircraft operations in Table 3-1

to determine the minimum survey frequency. As

airport operators accumulate data on the rate of change

of runway friction under various traffic conditions, the

scheduling of friction surveys may be adjusted to

ensure that evaluators will detect and predict marginal

friction conditions in time to take corrective actions.

TABLE 3-1. FRICTION SURVEY FREQUENCY

NUMBER OF DAILY

MINIMUM TURBOJET

AIRCRAFT LANDINGS

PER RUNWAY END

MINIMUM

FRICTION SURVEY

FREQUENCY

LESS THAN 15 1 YEAR

16 TO 30 6 MONTHS

31 TO 90 3 MONTHS

91 TO 150 1 MONTH

151 TO 210 2 WEEKS

GREATER THAN 210 1 WEEK

NOTE: Each runway end should be evaluated

separately, e.g., Runway 18 and Runway 36.

3-4. SURVEYS WITHOUT CFME. Research has

shown that visual evaluations of pavement friction are

not reliable. An operator of an airport that does not

support turbojet operations who suspects that a runway

may have inadequate friction characteristics should

arrange for testing by CFME. Visual inspections are

essential, however, to note other surface condition
AC 150/5320-12C 3/18/97

20

inadequacies such as drainage problems, including

ponding and groove deterioration, and structural

deficiencies.

3-5. GROOVE DETERIORATION. Periodically,

the airport operator should measure the depth and

width of a runway's grooves to check for wear and

damage. When 40 percent of the grooves in the

runway are equal to or less than 1/8 inch (3 mm) in

depth and/or width for a distance of 1,500 feet (457 m),

the grooves’ effectiveness for preventing hydroplaning

has been considerably reduced. The airport operator

should take immediate corrective action to reinstate the

1/4 inch (6 mm) groove depth and/or width.

3-6. MEASUREMENT OF PAVEMENT

SURFACE TEXTURE. When a friction test

identifies a pavement surface with inadequate friction

characteristics, the cause, such as rubber accumulation,

is often obvious. When the cause is not obvious, the

following guidance may be helpful in determining if

the deficiency is a result of a deterioration in surface

texture depth. Such deterioration may be caused by

weather influences, wear/polishing effects of aircraft

traffic, and contaminants including but not limited to

rubber deposits. Visual inspections cannot be relied

upon to identify pavement surfaces with poor texture.

Pavement texture depths can only be determined by

direct measurements. Even direct measurements may

be affected by the operator of the equipment, so they

should be used as only part of an overall pavement

friction evaluation.

Section 2. CFME - General

3-7. GENERAL REQUIREMENTS FOR CFME.

All airports with turbojet traffic should own or have

access to use of CFME. Not only is it an effective tool

for scheduling runway maintenance, it can also be used

in winter weather to enhance operational safety (see

AC 150/5200-30). Airports that have few turbojet

traffic operations may be able to borrow the CFME

from nearby airports for maintenance use, share

ownership with a pool of neighboring airports, or hire

a qualified contractor.

3-8. FAA PERFORMANCE STANDARDS FOR

CFME. Appendix 3 contains the performance

specifications for CFME. These standards should be

used by airport operators in procuring CFME and

replacement tires for the equipment.

3-9. FAA QUALIFIED PRODUCT LIST. The

equipment listed in Appendix 4 has been tested and

meets the FAA standards for CFME for use in

conducting maintenance friction tests.

3-10. USE OF DECELEROMETER. Since

decelerometers are not capable of providing continuous

friction measurements and do not give reliable results

on wet pavement surfaces, they are not approved for

conducting runway maintenance surveys as discussed

in this AC. However, the devices are approved for

conducting friction surveys on runways during winter

operations (reference AC 150/5200-30).

3-11.FEDERAL FUNDING OF CFME. The Airport

and Airway Improvement Act of 1982 (AAIA) includes

friction measuring equipment as an eligible item for

airport development. However, before programming or

procuring this equipment, airport operators should

contact their FAA Regional or Airports District Office

for guidance.

3-12.TRAINING OF PERSONNEL. The success of

friction measurement in delivering reliable friction

data depends heavily on the personnel who are

responsible for operating the equipment. Adequate

professional training on the operation, maintenance,

and procedures for conducting friction measurement

should be provided either as part of the procurement

package or as a separate contract with the

manufacturer. Also, recurrent training is necessary for

review and update to ensure that the operator

maintains a high level of proficiency. Experience has

shown that unless this is done, personnel lose touch

with new developments on equipment calibration,

maintenance, and operating techniques. A suggested

training outline for the manufacturers is given in

Appendix 5. Airport personnel should be trained not

only in the operation and maintenance of the CFME

but also on the procedures for conducting friction

surveys. These procedures are provided in Section 4

below. At airports where friction tests are performed

less frequently than quarterly, and CFME is not used

for winter operations, consideration should be given to

hiring a qualified contractor to perform tests.

3-13. CALIBRATION. All CFME should be checked

for calibration within tolerances given by the

manufacturer before conducting friction surveys.
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 3/18/97

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 Maintenanc

e Planning

New

Design/

Construction

Minimum Maintenanc

e Planning

New

Design/

Construction

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

K.J. Law 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.
3/18/97 AC 150/5320-12C

23

b. Friction Deterioration Below the

Maintenance Planning Friction Level (1000 ft).

When the averaged Mu value on the wet runway

pavement surface is less than the Maintenance

Planning Friction Level in Table 3-2 for a distance of

1000 feet (305 m) or more, the airport operator should

conduct extensive evaluation into the cause(s) and

extent of the friction deterioration and take appropriate

corrective action.

c. Friction Deterioration Below the

Minimum Friction Level. When the averaged Mu

value on the wet pavement surface is below 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 below the Maintenance Planning Friction

Level, corrective action should be taken immediately

after determining the cause(s) of the friction

deterioration. Before undertaking corrective measures,

the airport operator should investigate the overall

condition of the entire runway pavement surface to

determine if other deficiencies exist that may require

additional corrective action.

d. New Design/Construction Friction Level

for Runways. For newly constructed runway

pavement surfaces (that are either saw cut grooved or

have a PFC overlay) serving turbojet aircraft

operations, the averaged Mu value on the wet runway

pavement surface for each 500 foot (152 m) segment

should be no less than the New Design/Construction

Friction Level in Table 3-2.

3-21. COMPUTER EVALUATION OF FRICTION

TEST DATA. A manual evaluation of friction test

data as required by the criteria above can be tedious

and prone to human error. An IBM PC-compatible

computer program which performs this evaluation is

available free of charge. The computer program may

be downloaded from the FAA Airports Internet web

site at http://www.faa.gov/arp/software.htm.

Section 4. Conducting Texture Depth Measurements

3-22. RECOMMENDED TESTING. When friction

values meet the criteria in paragraphs 3-20.(a), 3-

20.(b), and 3-20.(c), no texture depth measurements

are necessary. When friction values do not meet the

criteria in paragraphs 3-20.(a), 3-20.(b), or 3-20.(c),

and the cause is not obvious (e.g. rubber deposits), the

airport operator should perform texture depth

measurements.

3-23 RECOMMENDED TEXTURE DEPTHS.

a. Newly Constructed Pavements. The

recommended average texture depth to provide good

skid-resistance for newly constructed concrete and

asphalt pavements is 0.045 inch (1.14 mm). A lower

value indicates a deficiency in macrotexture that will

require correction as the surface deteriorates.

b. Existing Pavements.

(1) When the average texture depth

measurement in a runway zone (i.e., touchdown,

midpoint, and rollout) falls below 0.045 inch

(1.14 mm), the airport operator should conduct texture

depth measurements each time a runway friction

survey is conducted.

(2) When the average texture depth

measurement in a runway zone is below 0.030 inch

(0.76 mm) but above 0.016 inch (0.40 mm), the airport

operator should initiate plans to correct the pavement

texture deficiency within a year.

(3) When the average texture depth

measurement in a runway zone (i.e., touchdown,

midpoint, and rollout) falls below 0.010 inch

(0.25 mm), the airport operator should correct the

pavement texture deficiency within 2 months.

c. Retexturing. Retexturing of the pavement

surface should improve the average texture depth to a

minimum of 0.030 inch (0.76 mm).

3-24.LOCATION OF MEASUREMENTS. Groove

depths are never included in texture depth

measurements. For grooved runway pavements,

texture depth measurements should always be located

in nongrooved areas, such as near transverse joints or

light fixtures, but as close as possible to heavily

trafficked areas.

3-25.TEST METHODS. A minimum of three texture

depth measurements should be taken in any area noted

as deficient. More measurements should be taken

when obvious textural changes in the pavement surface
AC 150/5320-12C 3/18/97

24

are observed. An average texture depth should be

computed for each area. Descriptions of the equipment

and methods used and the computations involved in

determining texture depths are as follows:

a. Equipment. The NASA Grease Smear

Method is used to determine the macrotexture of the

pavement surface by measuring the average distance

between the peaks and valleys in the pavement texture.

This method cannot be used to evaluate the pavement

microtexture. On the left in Figure 3-1 is shown the

tube which is used to measure the 1 cubic inch (15 cc)

volume of grease. On the right is shown the tightfitting plunger which is used to expel the grease from

the tube, and in the center is shown the rubber

squeegee which is used to work the grease into the

voids in the runway surface.

The sheet rubber on the squeegee is cemented to a

piece of aluminum for ease in use. Any general

purpose grease can be used. As a convenience in the

selection of the length of the measuring tube, Figure 3-

2 gives the relation between the tube inside diameter

and tube length for an internal tube volume of one

cubic inch (15 cu cm). The plunger can be made of

cork or other resilient material to achieve a tight fit in

the measuring tube.

b. Measurement. The tube for measuring the

known volume of grease is packed full with a simple

tool, such as a putty knife, with care to avoid entrapped

air, and the ends are squared off as shown in

Figure 3-3. A general view of the texture measurement

procedure is shown in Figure 3-4. The lines of masking

tape are placed on the pavement surface about 4 inches

(10 cm) apart. The grease is then expelled from the

measuring tube with the plunger and deposited

between the previously placed lines of masking tape. It

is then worked into the voids of the runway pavement

surface with the rubber squeegee, with care that no

grease is left on the masking tape or the squeegee. The

distance along the lines of masking tape is then

measured and the area that is covered by the grease is

computed.

3-26. COMPUTATION. After the area is completed,

the following equations are used to calculate the

average texture depth of the pavement surface:

Texture depth (inches) =Volume of Grease (cu. in.) 

Area Covered by Grease (sq. in.)

Average Texture Depth = Sum of individual Tests

Total Number of Tests
3/18/97 AC 150/5320-12C

25

FIGURE 3-1. GREASE-VOLUME MEASURING TUBE, PLUNGER, AND RUBBER SQUEEGEE
AC 150/5320-12C 3/18/97

26

FIGURE 3-2. MEASURING TUBE DIMENSIONS TO MEASURE

ONE CUBIC INCH OR FIFTEEN CUBIC CENTIMETERS
3/18/97 AC 150/5320-12C

27

FIGURE 3-3. MEASURING TUBE FILLED WITH GREASE
AC 150/5320-12C 3/18/97

28

FIGURE 3-4. ILLUSTRATION OF APPARATUS USED IN GREASE APPLICATION TECHNIQUE FOR

MEASURING PAVEMENT SURFACE TEXTURE DEPTH
3/18/97 AC 150/5320-12C

29

CHAPTER 4. MAINTAINING HIGH SKID-RESISTANCE

Section 1. Maintenance Considerations

4-1. NEED FOR MAINTENANCE. As traffic

mechanically wears down microtexture and

macrotexture and as contaminants build up on runway

pavements, friction will decrease to a point where

safety may be diminished. At joint use airports, where

high numbers of military aircraft operations occur, the

venting of excess fuel can lead to serious loss of

friction by either causing contaminant buildup or an oil

film on the pavement surface. Also, fog seal treatment

of HMA surfaces can substantially reduce the

pavement's coefficient of friction during the first year

after application. Surfaces which already have

marginally acceptable friction can become

unacceptable when given this type of surface treatment.

When the measured coefficient of friction values

approach or drop below the Maintenance Planning

Level as shown in Table 3-2 in chapter 3. Table 4-1

may be used as a tool for budgeting for and scheduling

appropriate and timely maintenance for removal of

contaminants and restoration of good friction

characteristics. As stated in chapter 3, the average

aircraft mix was based on mostly narrow body aircraft

with a few wide body aircraft operations included.

Rubber accumulation is dependent on the type and

frequency of aircraft landing operations; e.g., weight of

aircraft, the number of wheels that touchdown on the

surface, climate, runway length, and runway

composition. When more than 20 percent of the total

aircraft mix landing on any one runway end are wide

body aircraft, it is recommended that the airport

operator select the next higher level of aircraft

operations in Table 4-1 to determine the rubber

removal frequency. Experience and the use of CFME

will allow the airport operator to develop a schedule

specific to each runway.

TABLE 4-1. RUBBER DEPOSIT

REMOVAL FREQUENCY

NUMBER OR DAILY

TURBOJET AIRCRAFT

LANDING PER RUNWAY

END

SUGGESTED

RUBBER DEPOSIT

REMOVAL

FREQUENCY

LESS THAN 15 2 YEARS

16 TO 30 1 YEAR

31 TO 90 6 MONTHS

91 TO 150 4 MONTHS

151 TO 210 3 MONTHS

GREATER THAN 210 2 MONTHS

Note: Each runway end should be evaluated

separately, e.g. Runway 18 and Runway 36.

Section 2. Methods for Removing Contaminants

4-2. RECOMMENDED CONTAMINANT

REMOVAL TECHNIQUES. Several methods are

available for cleaning rubber deposits, other

contaminants, and paint markings from runway

surfaces. They include high pressure water, chemical,

high velocity impact, and mechanical grinding. After

the contaminants have been removed from the runway

surface by any of these methods, the airport operator

should conduct friction measurements to assure that

the Mu values have been restored to within 10 percent

of those on the uncontaminated center portion of the

runway and that both measurements are well within

the acceptable friction levels for safe aircraft

operations. The effectiveness of rubber deposit

removal procedures cannot be evaluated by visual

inspection. It is highly recommended that rubber

deposit removal contracts base payments on final tests

by CFME. A brief description follows for each of the

contaminant removal techniques. None of the

techniques should be used unless the runway is free of

standing water, snow, slush, and/or ice. Also,

chemical or water impact removal methods should not

be used if there is a danger of the fluids freezing.

The ultimate success of any method will depend on the

expertise of the equipment operator. Results can vary

from completely ineffective to a situation where all

rubber deposits are removed, but the underlying

pavement is significantly damaged. It is recommended

that airport operators require that a test section be

cleaned by the contractor to demonstrate that rubber

deposits will be removed without damage to the

underlying pavement.

a. Removal by High Pressure Water. A

series of high pressure water jets is aimed at the
AC 150/5320-12C 3/18/97

30

pavement to blast the contaminants from the surface,

allowing the water to transport the rubber particles to

the edge of the runway. The technique is economical,

environmentally clean, and effectively removes

deposits from the pavement surface with minimal

downtime to the airport operator. High-pressure water

blasting also may be used to improve the surface

texture of smooth pavements. Water pressures used

vary significantly. There are so many other parameters

that vary from one contractor's equipment to another,

however, that the pressure of the water used is not a

good indication of the potential for either effectiveness

or pavement damage. The airport operator should rely

on the contractor's experience, demonstrated expertise,

and references.

b. Removal by Chemicals. Chemical solvents

have been used successfully for removal of

contaminants on both PCC and HMA runways. Any

chemicals used on runways must meet Federal, state,

and local environmental requirements. For removal of

rubber deposits on PCC runways, chemicals are used

which have a base of cresylic acid and a blend of

benzene, with a synthetic detergent for a wetting agent.

For removal of rubber deposits on HMA runways,

alkaline chemicals are generally used. Because of the

volatile and toxic nature of such chemicals, extreme

care must be exercised during and after application. If

the chemicals remain on the pavement too long, the

painted areas on the runway and possibly the surface

itself could be damaged. It is also very important to

dilute the chemical solvent that is washed off the

pavement surface so that the effluent will not harm

surrounding vegetation or drainage systems or pollute

nearby streams and wildlife habitats. Detergents made

of metasilicate and resin soap can be used effectively to

remove oil and grease from PCC runway surfaces. For

HMA pavements, an absorbent or blotting material

such as sawdust or sand combined with a rubber

alkaline degreaser may be used.

c. High Velocity Impact Removal. This

method employs the principle of throwing abrasive

particles at a very high velocity at the runway

pavement surface, thus blasting the contaminants from

the surface. Additionally, the machine that performs

this operation can be adjusted to produce the desired

surface texture, if so required. The abrasive is

propelled mechanically from the peripheral tips of

radial blades in a high speed, fan like wheel. The

entire operation is environmentally clean in that it is

self-contained; it collects the abrasive particles, loose

contaminants, and dust from the runway surface; it

separates and removes the contaminants and dust from

the abrasive; and it recycles the abrasive particles for

repetitive use. The machine is very mobile and can be

removed rapidly from the runway if required by aircraft

operations.

d. Mechanical Removal. Mechanical grinding

that employs the corrugating technique has been

successfully used to remove heavy rubber deposits from

both PCC and HMA runways. It has also been used to

remove high areas such as bumps on pavement

surfaces or at joints where slabs have shifted or faulted.

This method greatly improves the pavement surface

friction characteristics. Pavement surfaces that are

either contaminated (rubber buildup or bleeding) or

worn can have their surface friction coefficient greatly

increased by a thin milling operation. This technique

removes a surface layer between 1/8 and 3/16 inch

(3.2 and 4.8 mm) in depth.
3/18/97 AC 150/5320-12C

Appendix 1

1 (and 2)

APPENDIX 1. QUALIFICATION PROCESS FOR CFME

1. FRICTION EQUIPMENT CORRELATION

PROGRAM. From 1982 through 1985, the FAA

conducted a series of tests to determine the correlation

of the Mu Meter with the Saab Friction Tester,

Skiddometer, and the Runway Friction Tester, using

the equipments' self-wetting systems on dry pavement

surfaces at NASA's Wallops Right Facility.

Correlation values were established for the Saab

Friction Tester, the Runway Friction Tester, the

Skiddometer, and the Mu Meter. Reference Appendix

2, Report No. DOT/FAA/AS-90-1, which shows the

results of the correlation trials conducted at NASA’s

Wallops Flight Facility in August 1989. Additional

devices have since been found to meet FAA

specifications. All devices found to meet FAA

specifications are listed in appendix 4.

2. FRICTION/SPEED RELATIONSHIPS FOR

PAVEMENT SURFACES. The relationship of speed

to friction has a profound influence on aircraft braking

performance when pavements have little or no

microtextural properties. According to the Unified

Mechanism of Rubber/Pavement Friction, the adhesion

component of friction, which is governed mainly by the

shear force between the tire and the pavement surface,

is high at lower speeds of up to about 100 mph. The

rubber couples well with a good microtextured surface

to provide high friction at the lower speeds. At speeds

over 100 mph, the hysteresis component of friction

governs. This component is the effect of damping or

reacting elastic pressure of rubber when deformed

around aggregate particles. The deformation is

produced best by good macrotextured surfaces. In

essence, the Unified Mechanism simply states that a

good macro/microtexture surface will provide relatively

high friction and flat friction speed gradient on wet

pavement surfaces. As speed increases, macrotextured

surfaces will provide good drainage to keep the

hydrodynamic pressure low and the tire in contact with

the pavement surface for a low friction/speed gradient.

However, a poor macrotextured pavement surface

cannot provide sufficient drainage for good

tire/pavement contact. Thus, the friction speed

gradient decreases rapidly.

The relationship of the friction/speed gradient was

determined at NASA's Wallops Flight Facility by

conducting friction surveys on several types of

pavement surfaces that represented a wide range of

friction values at speeds of 20, 40, 60, and 80 mph.

Testing operational runways at 20 mph is not

practicable, since a test of a 10.000' runway would take

approximately 6 minutes. Likewise, the distance

required to accelerate to and decelerate from 80 mph

would preclude testing most of a typical touchdown

zone. Therefore, a compromise is made and tests are

conducted at only two speeds, 40 and 60 mph. These

two speeds will provide an adequate representation of

the friction/speed gradient for the various textured

pavement surfaces encountered.

3. DEVELOPMENT OF PERFORMANCE

SPECIFICATION FOR FRICTION EQUIPMENT.

The following paragraphs discuss the qualification

process used to develop the performance specification

for the friction equipment and friction measuring tires.

a. Development of the Friction Equipment

Performance Specification. To qualify for Federal

funds, friction equipment performance standards had

to be developed. Friction tests were conducted at

NASA's Wallops Flight Facility to develop the

performance specification for friction measuring

equipment. The specification was developed to assure

the airport operator that the friction measuring

equipment would perform with reliability and

consistency on all types of pavement surface

conditions.

b. Development of the Tire Performance

Specification. Prior to 1989, only one friction

measuring tire was available for friction measuring

devices. During 1988, the E-17 committee of ASTM

requested the FAA to conduct tire performance tests on

two tires manufactured according to ASTM

specifications E-524, Specification for Standard

Smooth Tire for Pavement Skid-resistance Tests, and

E-670, Standard Test Method for Side Force Friction

on Paved Surfaces Using the Mu-Meter, and compare

these tires with the performance of the then FAA

standard tire. A tire performance specification was

developed for the test program. The tests were

conducted at NASA's Wallops Flight Facility in

August 1989. The tires are manufactured in the United

States by the McCreary Tire & Rubber Company of

Indiana, Pennsylvania and Dico Tire, Inc. of Clinton,

Tennessee.

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

Appendix 2

1

APPENDIX 2. RELATED READING MATERIAL

1. The latest issues of the following free publications

may be obtained from the U.S. Department of

Transportation, Warehousing and Subsequent

Distribution Section, SVC-121.23, Washington, DC

20590. AC 00-2, Advisory Circular Checklist, current

edition, contains the listing of all current issues of

circulars and changes thereto.

a. AC 150/5200-28, Notices to Airman

(NOTAMS) for Airport Operators.

b. AC 150/5200-30, Airport Winter Safety and

Operation.

c. AC 150/5320-6, Airport Pavement Design

and Evaluation.

2. Copies of the following publications may be

obtained from the Superintendent of Documents, U.S.

Government Printing Office, Washington, DC 20402.

Send check or money order with your request made

payable to the Superintendent of Documents in the

amount stated. No C.O.D. orders are accepted.

a. AC 150/5300-13, Airport Design ($15.00).

b. AC 150/5370-10, Standards for Specifying

Construction of Airports, current edition ($18.00).

c. AC 150/5380-6, Guidelines and Procedures

for Maintenance of Airport Pavements ($7.00).

3. Copies of Part 15, Road, Paving, Bituminous

Materials, Skid-resistance, and Skid-resistance of

Highway Pavements, STP 530, may be obtained from

the American Society For Testing and Materials, 1916

Race Street, Philadelphia, Pennsylvania 19103.

4. Copies of the following publications may be

obtained from the National Technical Information

Service, Springfield, Virginia 22151.

a. Pavement Grooving and Traction Studies,

Report No. NASA SP-5073, 1969.

b. A Comparison of Aircraft and Ground

Vehicle Stopping Performance on Dry, Wet, Flooded,

Slush, and Ice-covered Runways, Report No. NASA

TN D-6098, November 1970.

c. Runway Friction Data for 10 Civil Airports

as Measured with a Mu Meter and Diagonal Braked

Vehicle, Report No. FAA-RD-72-61, July 1972.

d. Effects of Pavement Texture on Wet Runway

Braking Performance, Report No. NASA TN D-4323,

January 1969.

e. Porous Friction Surface Courses, Report

No. FAA-RD-73-197, February 1975.

f. Laboratory Method for Evaluating Effect of

Runway Grooving on Aircraft Tires, Report No. FAARD-74-12, March 1974.

g. Investigation of the Effects of Runway

Grooves on Wheel Spin-up and Tire Degradation,

Report No. FAA-RD-71-2, April 1971.

h. Environmental Effects on Airport Pavement

Groove Patterns, Report No. FAA-RD-69-37, June

1969.

i. The Braking Performance of an Aircraft Tire

on Grooved Portland Cement Concrete Surfaces,

Report No. FAA-RD-80-78, January 1981.

j. Braking of an Aircraft Tire on Grooved and

Porous Asphaltic Concrete, Report No. DOT-FAARD-82-77, January 1983.

k. Analytical and Experimental Study of

Grooved Pavement Runoff, Report No. DOT-FAA-PM83/84, August 1983.

l. Surveys of Grooves in Nineteen Bituminous

Runways, Report No. FAA-RD-79-28, February 1979.

m. Modified Reflex-Percussive Grooves for

Runways, Report No. DOT-FAA-PM-82-8, March

1984.

n. Reliability and Performance of Friction

Measuring Tires and Friction Equipment Correlation,

Report No. DOT/FAA/AS-90-1, March 1990.

5. Copies of MS-16, Asphalt in Pavement

Maintenance, may be obtained from the Asphalt

Institute Building, College Park, Maryland 20740.
AC 150/5320-12C 3/18/97

Appendix 2

2

6. Copies of Maintenance Practices for Concrete

Pavements, may be obtained from the Portland Cement

Association, Old Orchard Road, Skokie, Illinois 60076.

7. Copies of the following publications may be

obtained from the Highway Research Board, National

Academy of Sciences, 2101 Constitution Avenue,

Washington, D.C. 20418.

a. Skid-resistance, National Cooperative

Highway Research Program (NCHRP) Synthesis of

Highway Practice 14, 1972.

b. Pavement Rehabilitation - Materials and

Techniques, National Cooperative Highway Research

Program (NCHRP) Synthesis of Highway Practice 9,

1972.

c. Factors Affecting Skid-resistance and Safety

of Concrete Pavements, Special Report No. 101, 1969.

d. Road Surface Texture and the Slipperiness of

Wet Roads, Record No. 214, 1968.

e. Pilot Field Study of Concrete Pavement

Texturing Methods, Record No. 389, 1972.

f. Prediction of Skid-resistance Gradient and

Drainage Characteristics of Pavements, Record

No. 131, 1966.

g. Standard Nomenclature and Definitions for

Pavement Components and Deficiencies, Special

Report No. 113, 1970.

h. Development of Specifications for SkidResistant Asphalt Concrete, Record No. 396, 1972.

i. Skid-resistance of Screenings for Seal Coats,

Record No. 296, 1968.

8. Copies of the following technical bulletins may be

purchased from the American Concrete Paving

Association, Suite 490, 3800 N. Wilke Rd., Arlington

Heights, Illinois, 60004-1268.

a. Texturing of Concrete Pavements, Bulletin

No. 1.

b. Interim Recommendations for the

Construction of Skid-Resistant Concrete Pavement,

Bulletin No. 6.

c. Guideline for Texturing of Portland Cement

Concrete Highway Pavements, Bulletin No. 19.

9. Copies of Evaluation of Two Transport Aircraft

and Several Ground Test Vehicle Friction

Measurements Obtained for Various Runway Surface

Types and Conditions, NASA Technical Paper 2917,

February 1990, may be obtained from NASA, under

the Code NTT-4, Washington, DC 20546-0001.

10. Copies of ASTM Specifications can be obtained

from ASTM, 1916 Race Street, Philadelphia,

Pennsylvania 19103.
3/18/97 AC 150/5320-12C

Appendix 3

1

APPENDIX 3. PERFORMANCE SPECIFICATIONS FOR CFME

1. FRICTION EQUIPMENT PERFORMANCE

STANDARD. The friction measuring equipment may

be self-contained or towed. If towed, the tow vehicle

will be considered an integral part of the device. The

vehicles and/or trailers shall meet all applicable

Federal and state laws and/or regulations for vehicles

and/or trailers for use on public highways. The side

force friction measuring device, the Mu Meter, shall

meet the Standard Test Method given in ASTM E 670.

The Standard Test Method for the fixed brake slip

devices is under preparation by the ASTM Committee.

a. The Friction Measuring Equipment shall

do the following:

(1) provide fast, continuous, accurate, and

reliable friction measurements for the entire length of

the runway, less the differences required for

accelerating and decelerating the vehicle at the runway

ends.

(2) be designed to sustain rough usage and

still function properly and provide efficient and reliable

methods of equipment calibration.

(3) be capable of automatically providing

the operator with a selection of average friction values

for both a 500 foot (150 m) and one-third segment of

runway length. In addition, it shall be capable of

providing data, whereby, the average friction value for

any length of runway can be manually calculated.

(4) be capable of producing a permanent

trace of friction measurements versus pavement length

at a scale of at least one inch (25 mm) equals 300 feet

(90 m).

(5) be capable of consistently repeating

friction averages throughout the friction range on all

types of pavement surfaces. Friction averages for each

500 foot (150 m) segment located on the pavement

surface must be within a confidence level of

95.5 percent, or two standard deviations of ±.06 Mu

numbers.

(6) contain a self-wetting system that

distributes water in front of the friction measuring

wheel(s) at a uniform depth of 0.04 inch (1 mm). The

manufacturer shall provide documentation to show that

the flow rate is within a tolerance of ±10 percent for

both test speeds.

(7) be able to conduct friction surveys at

speeds of 40 and 60 mph (65 and 95 km/hr), within a

tolerance of ±3 mph (±5 km/hr).

(8) include a complete set of the latest

operation and maintenance manuals including

guidelines for training airport personnel. The training

manuals shall include the current copy of this AC.

(9) have electronic instrumentation (solidstate electronics), including a keyboard for data entry,

that will enhance the information gathering and

analysis capability of the equipment, and provide the

operator more convenience in equipment operation and

performance. The information gathered during a

friction survey should be stored in an internal

microprocessor memory and be readily visible to the

operator of the vehicle. This will allow for the

examination of data, printouts, and calculation of

average friction values over all or any portion of the

test run. Each printout of the chart produced by the

microprocessor unit shall include the following

recorded information: runway designation and date;

time of friction survey; a continuous trace of the

friction values obtained for the entire runway length

minus the acceleration/deceleration distances; printed

marks depicting each 100 foot (30 m) increment of the

runway length so easy reference can be made by the

operator in identifying specific areas on the runway

pavement surface; average friction value for 500 foot

(150 m) and one-third segments of the runway length

as preselected by the operator; and average vehicle

speed for that segment.

b. The vehicle shall:

(1) be able to conduct friction surveys at

speeds of 40 and 60 mph (65 and 95 km/hr), within a

tolerance of ±3 mph (±5 km/hr). The vehicle, when

fully loaded with water, shall be capable of accelerating

to these speeds within 500 and 1000 feet (150 and

300 m) from the starting position, respectively.

(2) be equipped with electronic speed

control.

(3) conform to the requirements of AC

150/5210-5, Painting, Marking, and Lighting of

Vehicles Used on an Airport, for airfield service

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

Appendix 3

2

(4) be equipped with transceiver(s)

necessary for communication with airport operations

and air traffic control.

(5) be equipped with a water tank

constructed of strong lightweight material, of sufficient

capacity to complete a friction survey on a 14,000 foot

(4,267 m) runway in one direction and all necessary

appurtenances to deliver the required water flow rate to

the friction measuring wheel(s).

(6) be equipped with appropriate heavy duty

shock absorbers and heavy duty suspension to

adequately handle imposed loads.

(7) be equipped with a device that will

regulate the water flow within the confines of the

vehicle near the driver's position. Where flow

regulation is automatic, no device is required in the

vehicle.

(8) be equipped with internally controlled

spot lights on each side of the vehicle. For trailer

mounted equipment, the tow vehicle shall also be

equipped with at least two floodlights mounted such

that the friction measuring device and rear portion of

the tow vehicle is illuminated to a level of at least

20 foot-candles within an area bounded by lines 5 feet

(2 m) on either side of the friction measuring device

and 5 feet (2 m) in front of and behind the friction

measuring device.

(9) be equipped with an air conditioner

when specified by the purchaser.

2. TIRE PERFORMANCE STANDARD. The

friction measuring equipment shall be furnished with

measuring tires which are designed for use in

conducting friction surveys and which meet ASTM

standard E670, E-5551, or E-1844, as appropriate.

Nonribbed (blank) tire(s) shall be used to eliminate the

effect of tire tread wear and provide greater sensitivity

to variations in pavement surface texture. The tires

shall be furnished with split rims and the tubes shall

have curved valve stems. The manufacturer of the

friction equipment shall provide the airport user with a

calibrated pressure dial gauge.
3/18/97 AC 150/5320-12C

Appendix 4

1 (and 2)

APPENDIX 4. FAA-APPROVED CFME

AIRPORT SURFACE FRICTION TESTER AB

PL 2217

S-761 92 Norrtalje

SWEDEN

AIRPORT SURFACE FRICTION TESTER

+46 1 766 96 90

FAX +46 1 766 98 80

AIRPORT TECHNOLOGY USA

Six Landmark Square - Fourth Floor

Stamford, CT 06901-2792

SAFEGATE FRICTION TESTER

(203) 359-5730

FAX (202) 378-0501

BISON INSTRUMENTS, INC.

5610 Rowland Road

Minneapolis, MN 55343-8956

MARK 4 MU METER

(612) 931-0051

FAX (612) 931-0997

INTERTECH ENGINEERING

726 South Mansfield Avenue

Los Angeles, CA 90036

TATRA FRICTION TESTER

(213) 939-4302

FAX (213) 939-7298

K. J. LAW ENGINEERS, INC.

42300 West Nine Mile Road

Novi, Michigan 48375-4103

RUNWAY FRICTION TESTER (M 6800)

(313) 347-3300

FAX (313) 347-3343

AEC, AIRPORT EQUIPMENT CO.

P.O. Box 20079

S-161 02 BROMMA

SWEDEN

BV-11 SKIDDOMETER

+46 8 295070

FAX +46 8 6275527

E-mail aec@aec.se

FINDLAY, IRVINE, LTD.

Bog Road, Penicuik

Midlothian EH 26 9BU

Scotland

GRIPTESTER FRICTION TESTER

+44 1968 672111

FAX +44 1968 672596

NORSEMETER

P.O. Box 42

Olav Ingstads vei 3

1351 Rud

Norway

RUNAR RUNWAY ANALYSER AND RECORDER

+47 67 15 17 00

FAX +47 67 15 17 01

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

Appendix 5

1 (and 2)

APPENDIX 5. TRAINING REQUIREMENTS OUTLINE FOR CFME

1. GENERAL DISCUSSION. The following

paragraph lists the major items which should be

considered in developing a training program for airport

personnel responsible for operating and maintaining

CFME. Whenever a major change in equipment

design occurs, the training and instruction manuals

should be revised. A document titled Training and

Instruction Manual should always be provided to the

airport personnel by the manufacturer and kept

updated.

2. TRAINING REQUIREMENTS OUTLINE.

a. Classroom Instruction.

(1) Purpose of Training Program.

(2) General Discussion on Pertinent Federal

Aviation Regulations.

(3) General Discussion on Pertinent ACs.

(4) General Discussion on Pertinent ASTM

Standards.

(5) General Overview of Program.

(6) Review of Requirements in

AC 150/5320-12.

(i) Coefficient of Friction Definition.

(ii) Factors Affecting Friction

Conditions.

(iii) ASTM Standards for CFME.

(iv) ASTM Standards for Friction

Measuring Tires.

(v) Operation of CFME.

(vi) Programming the Computer for

FAA and ICAO Formats.

(vii) Maintenance of CFME.

(viii) Procedures for Reporting Friction

Numbers.

(ix) Preparation and Dissemination of

NOTAMS.

(7) Orientation to the Calibration, Operation,

and Maintenance of CFME.

b. Field Experience. Operation and

Maintenance of CFME.

c. Testing. Solo Test and Written Examination

on All Items Covered in Course.

d. Award Of Training Certificate.