publications receives immediate dissemination by the  NOTAM system. The NOTAM information could affect your  decision to make the flight. It includes such information as  taxiway and runway closures, construction, communications,  changes in status of navigational aids, and other information  essential to planned en route, terminal, or landing operations.  Exercise good judgment and common sense by carefully  regarding the information readily available in NOTAMs.  Prior to any flight, pilots should check for any NOTAMs that  could affect their intended flight. For more information on  NOTAMs, refer back to Chapter 1, “Pilot and Aeronautical  Information” section.  The Automated Terminal Information Service (ATIS) is a  recording of the local weather conditions and other pertinent  non-control information broadcast on a local frequency in a  looped format. It is normally updated once per hour but is  updated more often when changing local conditions warrant.  Important information is broadcast on ATIS including  weather, runways in use, specific ATC procedures, and any  airport construction activity that could affect taxi planning.  When the ATIS is recorded, it is given a code. This code is  changed with every ATIS update. For example, ATIS Alpha  is replaced by ATIS Bravo. The next hour, ATIS Charlie is  recorded, followed by ATIS Delta and progresses down the  alphabet.  Prior to calling ATC, tune to the ATIS frequency and listen to  the recorded broadcast. The broadcast ends with a statement  containing the ATIS code. For example, “Advise on initial  contact, you have information Bravo.” Upon contacting the  tower controller, state information Bravo was received. This  allows the tower controller to verify the pilot has the current  local weather and airport information without having to  state it all to each pilot who calls. This also clears the tower  frequency from being overtaken by the constant relay of  the same information, which would result without an ATIS  broadcast. The use of ATIS broadcasts at departure and arrival  airports is not only a sound practice but a wise decision.  There are markings and signs used at airports that provide  directions and assist pilots in airport operations. It is important  for you to know the meanings of the signs, markings, and lights  that are used on airports as surface navigational aids. All airport  markings are painted on the surface, whereas some signs are  vertical and some are painted on the surface. An overview of the  most common signs and markings are described on the following  pages. Additional information may be found in Chapter 2,  A displaced threshold is a threshold located at a point on  the runway other than the designated beginning of the  runway. Displacement of a threshold reduces the length  of runway available for landings. The portion of runway  behind a displaced threshold is available for takeoffs in either  direction, or landings from the opposite direction. A ten feet  wide white threshold bar is located across the width of the  runway at the displaced threshold, and white arrows are  located along the centerline in the area between the beginning  of the runway and displaced threshold. White arrow heads  are located across the width of the runway just prior to the  threshold bar.  [Figure 14-6A  and  B]  When the threshold is relocated, the closed portion of the  runway is not available for use by aircraft for takeoff or  landing, but it is available for taxi. When a threshold is  relocated, it closes not only a set portion of the approach  end of a runway, but also shortens the length of the opposite  direction runway. Yellow arrow heads are placed across the  width of the runway just prior to the threshold bar.  It is sometimes necessary, due to construction or runway  maintenance, to close only a portion of a runway. When  a portion of a runway is closed, the runway threshold is  relocated as necessary. It is referred to as a relocated threshold  and methods for identifying the relocated threshold vary. A  common way for the relocated threshold to be marked is  a ten foot wide white bar across the width of the runway.  [Figure 14-5A  and  B]  Since aircraft are affected by the wind during takeoffs and  landings, runways are laid out according to the local prevailing  winds. Runway numbers are in reference to magnetic north.  Certain airports have two or even three runways laid out in the  same direction. These are referred to as parallel runways and  are distinguished by a letter added to the runway number (e.g.,  runway 36L (left), 36C (center), and 36R (right)).  Runway markings vary depending on the type of operations  conducted at the airport. A basic VFR runway may only  have centerline markings and runway numbers. Refer to  Appendix C of this publication for an example of the most  common runway markings that are found at airports.  “Aeronautical Lighting and Other Airport Visual Aids,” of  the Aeronautical Information Manual (AIM).  Automated Terminal Information Service (ATIS)  Runway Markings and Signs  Relocated Runway Threshold  Displaced Threshold  Airport Markings and Signs  14-5 