If you have ever glanced out the window during a landing, you may have noticed that the runway bears long black streaks of rubber, predominately around the aiming point markers. The reason for this is because when a plane touches down the tires are not spinning and the time it takes for the tires to get up to speed is known as the “spin up time.” During this time the tires are dragging along the runway and being put under pressure by the weight of the aircraft. The friction built up causes the rubber to polymerize and harden to the runway surface. This hardened rubber decreases friction which increases the chance for aircraft to hydroplane, which is a large safety concern. The airport has a choice of methods to remove the build up of rubber.

Read the rest of this entry »