Airplanes depend on friction between runway and tires to be able to safely land the aircraft.
Over time, the skid-resistance of runway pavement deteriorates due to weathering, usage, aging and contaminants. The most persistent contaminant problem is deposits of rubber from tires of landing jet aircraft. Heavy rubber deposits can completely cover the pavement surface texture causing loss of aircraft braking capability and directional control, particularly when runways are wet.
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