Monthly Archives: April 2016

Airport 101: Signs Point the Way at Chicago Executive

PWK-19As they do around town, signs tell pilots where they are on Chicago Executive Airport and point the way to the runway and ramp and the taxiways that connect them. The only difference is that airport signs are color coded, lighted, and much closer to the ground on their frangible mounts. And they are sometimes painted on the pavement, usually identifying positions on low visibility taxi routes. In all, there are six types of airport signs. They relay mandatory instructions, location, direction, destination, information, and runway distance remaining.

Mandatory instruction signs are red with white letters and identify critical areas, such as the entrance to a runway or areas where aircraft entry is prohibited. Runway hold position signs are adjacent to the yellow hold short markings on the pavement and their alphanumeric display identifies the intersecting runway. If the taxiway intersects the runway at midfield, the runway numbers on the sign correspond, left and right, to the respective runway’s threshold.  Similar signs that bear a runway number and APCH or ILS indicate holding positions that keep aircraft a safe distance from the runway in foul weather so they do not interfere with instrument approach operations or the electronic systems that are guiding pilots to the runway.

Location, direction, and destination signs use combinations of yellow and black. Taxiway location signs use yellow characters on a black background with a yellow border. Often they are connected to direction or runway holding signs. Direction signs use black symbols in a yellow background and identify the intersecting taxiway with its alphanumeric designator and an arrow pointing in the direction a pilot would normally be expected to turn.

Direction signs are generally located on the left side of the taxiway before an intersection. If there is more than one way to go, the taxiway designations and their associated arrows are displayed clockwise starting from the first taxiway on the pilot’s left.

PWK-17Information signs have black characters on a yellow background and provide pilots with all sorts of pertinent information such as applicable radio frequencies or noise abatement procedures. Their content is determined by each airport’s operator.

Runway distance remaining signs are white numbers on a black background and are installed along one or both sides of a runway. The number indicates the distance, in thousands of feet, of the remaining useable runway. The last sign—1—will be at least 950 feet from the end of the runway.

All signs work in conjunction with pavement markings, which correspond to each airport’s diagram. The diagram is the pilot’s airport map that shows and names each runway and taxiway that lead to ramps and hangars and fixed-base operators. And at airports with towers, like Chicago Exec, the ground controller provides them with a taxi clearance that delineates their route from point to point, and will provide progressive instructions to newcomers that will lead them, turn-by-turn, to where they want to go.

Airport 101: Pavement Markings Keep Pilots in Line

PWK-59Chicago Executive Airport is one of thousands of airports that dot the American landscape. Each of them is different, but pilots have little trouble navigating around them because each of them use standardized pavement markings on the taxiways and runways that safely and efficiently guide them from the ramp to the sky. (Although they didn’t offer much help to the runners who raced about the airport several years ago, but they did get to see them at close range.)

Runway markings are white, and the elements employed depend on the type of approach pilots make to it. Runways with visual approaches, where the pilot eyeballs his arrival, has the fewest markings, the runway number, which is its magnetic heading to the nearest 10 degrees, and a centerline. These are on all runways. If the strip is 4,000 feet or longer or used by jets, it will have a visual aiming point, two broad white stripes on either side of the centerline approximately 1,000 feet from the threshold.

If it is intended for commercial use, markings (either a series of longitudinal or one lateral stripe) identify the pavement suitable for landing. A number of airports, like Chicago Exec, have displaced thresholds, usually to ensure an airplane’s safe approach to touchdown. Arrows on the pavement point to where the legal landing area begins.

All runways served by a nonprecision instrument approach, which in bad weather provides horizontal guidance to the runway, have these four markings. Chicago Exec has precision instrument approaches leading to both ends of Runway 16, which also provides vertical guidance to the pavement, which is why it has a touchdown zone. The rectangular bars are arranged in symmetrical pairs spaced 500 feet apart. As the number of bars decreases, so does the length of the remaining runway. Precision runways also have side stripes.

PWK-34All taxiway markings are yellow, and a centerline and markings denoting holding positions are common to all of them. A continuous strip 6 to 12 inches wide, the centerline does not guarantee wingtip clearance with other aircraft or obstacles. A line indicating the edge of the taxiway is applied when it does not correspond to the end of pavement.

Chicago Exec has an enhanced centerline, yellow dashes that parallel the continuous centerline, which tells pilots they are approaching a runway holding position and should be slowing down and preparing to stop, or hold short of the runway or intersections. Hold-short markings have two solid stripes on one side and two dashed lines on the other. Airplanes must stop when approaching the solid lines, which are on the taxiway side of a runway intersection. They may continue without stopping when on the dashed-line side, which they face when exiting the runway after landing.

Solid white lines on either side of a dashed centerline denote the edges of vehicle roadways that cross pavement also intended for aircraft. Some airports also use “zipper” markings, alternating white blocks. In either case, aircraft have the right of way. A thick white block on the pavement denotes where vehicles must stop at intersecting roadways or before crossing taxiways or other operational areas.

Working in concert with an airport’s pavement markings are a variety of signs of different colors that tell pilots where they are on the airport, and which way they should turn to reach their desired destination whether it is the departure end of a runway or a parking area. We’ll introduce them in our next Airport 101.