"TORA" is a commonly used abbreviation, which denotes the "takeoff run available." The TORA is the length of runway that has been authorized as available and suitable for an airplane to use as it takes off from the ground. "LDA," in contrast," denotes the "landing distance available" and suitable to planes preparing to land.
"ALS" stands for "approach lighting system." The approach lighting system is the fixture installed on the approach end of a runway. It consists of a series of lightbars which extend outward from the end of the runway. "REIL" denotes "runway end identification lights," which are unidirectional lights that face the approach direction at a runway threshold. "RCLS" stands for "runway centerline lighting system," which is the system of white lights along the centerline of a runway. "TDZL" stands for "touchdown zone lights," which consists of bars of three white lights on either side of the centerline.
The abbreviation "PAPI" denotes the "precision approach path indicators." These indicators are the four red lights that run alongside the runway. Typically, these lights are the ones seen by passengers on board a plane. They are not acknowledged as a part of the runway lighting system, although they still play an important role in runway operations. Their purpose is to facilitate a smooth descent, as they run parallel to the runway.
"PCN" describes "pavement classification number." A runway's PCN is an indication of its strength and durability to handle the forces of heavy aircraft. The "ACN" is the "aircraft classification number." The ACN describes the load that an aircraft exerts on the pavement. Calculations of PCN and ACN are necessary to ensure that planes to not unduly burden runways, taxiways and ramps. In order to preserve their safety and function, these parts of the ground have to remain relatively free of wear and tear.
