What system is used to distinguish among parallel runways?

The system used to distinguish among parallel runways utilizes numbers and letters. Each runway is assigned a number based on its compass heading, rounded to the nearest tenth, and if there are parallel runways, the runway number will be followed by a letter to denote its specific location, such as L for left, R for right, and C for center. This arrangement ensures that pilots and air traffic controllers have a clear and standardized reference for the runways they are using during takeoff, landing, and taxiing.

In contrast, options like colors, letters, or shapes do not provide the same level of clarity or standardization necessary for the safety and efficiency of airport operations. While letters are involved in the naming of parallel runways, it is the combination of both numbers and letters that serves as the official system for runway identification.