Runway

A runway is a surface on an airport used for takeoffs and landings of aircraft. They are often made out of pavement, though other unpaved surfaces are used, such as dirt, sod, and gravel. They can be many different lengths, from 500m for STOL use to 11900m dirt runways at Edwards AFB.

Parts of a Runway

Runway Safety Area

Around the runway, there is a runway safety area, which is flat and mostly clear of objects. This is to make sure that there are no loose items on the ground near the runway that could impede aircraft using the runway.

Blast Pads

Often constructed at the beginnings and ends of runways are blast pads. These are to protect the runway and ground before it from jet blast produced by aircraft. If these blast pads are not there, terrain before the runway could degrade allowing the runway's surface to crumble towards it. When there are not areas at the ends of runways that are flat and smooth in case of overruns, such as at KMDW, these are often made into EMAS to help stop planes in overruns. They have yellow chevrons painted over them and are not suitable to land, take off, or taxi on unless emergency.

Threshold

This is the beginning of the runway, from the blast pad to blast pad. There are normally a series of white lines, with the identification after that, to identify the runway, one on each end, in normal circumstances. Extremely rarely, in the case of EDDF, only one end is numbered, and because of this, this is the only used end. This threshold may be displaced from the start of the runway, see below.

Displaced Threshold

Displaced thresholds displace the normal threshold from the beginning of the runway. These are often constructed due to the fact that aircraft cannot land at the beginning of the runway due to noise restrictions or pavement strength. There are arrows pointing in the direction down the runway on them, leading up to the threshold.