The Night Airport Environment
An airport at night can be a dazzling light show. At a large airport, the grounds can be covered in a multitude of different colored taxiway lights; a small airport may have only a single rotating beacon! From sequentially flashing white lights to constant blues, it can be difficult to distinguish the significance of each light. Pilots must know the importance and location of each different light and taxiway reflectors on the airport, so that they may make important decisions quickly and safely. As runway incursions (incidents where two aircraft occupy a runway simultaneously) are some of the most common - and most deadly - accidents in the world of aviation, pilots should study all airport markings in order to ensure safety. Numerous safety programs have been employed, and the Aircraft Owners and Pilot’s Association (AOPA) offers several online courses intended to help pilots become familiar with airport markings.
A taxiway is the paved area that aircraft traverse on their way to either the runway for departure, or to the ramp (or apron) to disembark and shutdown. At a major airport, this paved area must be heavily reinforced to support the immense weight of huge jet airliners. Taxiways are built to a specific width to allow passage by large aircraft, and generally have a yellow line painted down their middle. This line aids the pilot in keeping the aircraft centered on the taxiway.
At night, a pilot sitting high in a lighted cockpit may have difficulty distinguishing dark pavement from unlit grass. Because of this, taxiways are lined with blue lights to allow the pilot to easily navigate them. The taxiway may also be equipped with taxiway centerline lights, placed along the painted yellow line on the taxiway. These lights are green.
Taxiways are generally painted with many standardized markings to aid pilots in navigation. These taxiway markers are situated so that they can be easily seen during the daytime, and also easily seen when a landing or taxi light is employed at night. All taxiways will employ a centerline marking, in the form of a single yellow painted line.
Taxiways will also display runway holding position markings when they intersect with a runway; a runway hold position marking consists of four solid yellow lines and two dashed yellow lines. The solid yellow lines are always on the side of the runway on which an aircraft is expected to hold position.
Finally, taxiways may display edge markings to help pilots recognize the side of a particular taxiway. These markings will consist of either a solid double yellow line, or a dashed double yellow line. Solid double yellow lines are used at the edge of a taxiway when the area intended for aircraft use ends; dashed yellow lines will be employed if the area of use continues (for example, onto the ramp) but the taxiway does not.
Taxiway Edge Lighting
Taxiway edge lights are constant and blue in color. These lights are generally activated just before dusk, or at any time when visibility is poor. The taxiway edge lights are elevated from the ground, but are low enough to ensure that aircraft with long, low wings will have clearance. Almost all airports, including smaller general aviation airports, will employ this type of taxiway lighting. However, some airports will not have any sort of lighting at night, and may be restricted to day use only; pilots should check the Airport/Facility directory to determine the type of lighting available at the airport in question.
Taxiway Centerline Lighting
Some airports may have taxiway centerline lighting. This type of lighting is green in color. The taxiway centerline lights are embedded in the pavement of the centerline, allowing aircraft to taxi over them. In a poor visibility or low light situation, a pilot can simply run the nose wheel of his aircraft along the green centerline lighting, ensuring that he is centered on the taxiway. Aircraft so equipped should still utilize any available taxi lights installed on board the aircraft, as well as any other exterior lighting that may aid visibility.