If you have ever walked on ice, you know that it is easy to slip and fall. This is because ice has little friction, a resistive force. The higher the friction levels, the better the grip. The same goes for rubber and contaminate accumulation on pavement and runway surfaces. The greater the accumulation of materials is, the lower the friction levels. Every time an aircraft lands, its tires deposit approximately 1 to 1.5 pounds (454g) of rubber onto the surface. The build-up of these heavy deposits can over time, if not treated properly; reduce the friction levels of the surface, potentially causing the aircraft to lose braking capabilities and directional control. Here is a recent article from, “The Time Of India” that shows a real world example of the challenges of not properly maintaining the rubber build up can cause: CLICK HERE FOR ARTICLE
1 LB (454g) of rubber is deposited with every landing!
Depending on the volume and type of aircraft traffic, runway rubber removal and cleaning may need to be performed frequently. But just how frequently is it necessary?…
Runway Surface Evaluation
In order to define how frequently runway rubber removal and cleaning needs to be performed, we must first determine how frequently the runway friction levels should be tested. Each runway should be evaluated individually using both visual inspection as well as the use of a test device.
Number Of Daily Minimum Aircraft Landings Per Runway
Minimum Friction Testing Frequency
Less than 15
16 to 30
31 to 90
91 to 150
151 to 210
Greater than 210
*Reference table 1 used from the Department of the Air Force – Headquarters Air Force Civil Engineer Support Agency, Engineering Technical Letter (ETL) 04-10 (Change 1): Determining the Need for Runway Rubber Removal (May 2004)
Using a Federal Aviation Administration (FAA) approved Continuous Friction Measuring Equipment (CFME) device (listed in the table below), runway friction levels can be measured to confirm whether or not runway rubber removal and cleaning needs to be executed. The CFME will help determine the surface friction deterioration and assist in developing a corrective action plan to ensure the safety of runways. The below friction level classifications were developed from correlation tests at the National Aeronautics and Space Administration’s (NASA) Wallops Flight Facility.
- When runway friction levels are less than the Planning Level, but above the Action level at both speeds measured, no immediate action is required, however, at this point, runway rubber removal should be scheduled to occur prior to the next friction test.
- When the runway friction levels are below the Action Level, action should be taken immediately to remove the rubber and contaminate build-up on the surface using appropriate runway rubber removal equipment.
CFME Test Device
Levels Measured at 40 MPH (65K/HR)
Levels Measured at 60 MPH (95K/HR)
Airport Surface Friction Tester
GripTester Friction Tester
RUNAR (Runway Analyser and Recorder)
Runway Friction Tester (M 6800)
*Reference table 2 and attachment 2 used from the Department of the Air Force – Headquarters Air Force Civil Engineer Support Agency, Engineering Technical Letter (ETL) 04-10 (Change 1): Determining the Need for Runway Rubber Removal (May 2004)
Although the above evaluation and maintenance guidelines are recommended, all facets of the runway as well as the volume of aircraft landings needs to be taken into account when determining the frequency of removal needed. Deferment of friction testing and necessary runway rubber removal creates hazardous conditions for aircraft landings, decreasing the safety of passengers and airport personnel.
When was the last time you tested your runway friction levels or performed the essential task of runway rubber removal?
For more information, download our Runway Rubber Removal Guide.