and off-route VORs are used to establish intersections. NDBs  are sometimes collocated with intersections, in which case  passage of the NDB would mark the intersection. A bearing to  an off-route NDB also can provide intersection identification.  A localizer course used to identify an intersection is depicted  by a feathered arrowhead symbol on the en route chart  ( ). If feathered markings appear on  the left-hand side of the arrowhead ( ),  a back course (BC) signal is transmitted. On AeroNav Products  en route charts, the localizer symbol is only depicted to identify  an intersection. Off-route VORs remain the most common means of  identifying intersections when traveling on an airway. Arrows  depicted next to the intersection   indicate the NAVAID  to be used for identification. Another means of identifying an  intersection is with the use of DME. A hollow arrowhead  indicates DME is authorized for intersection identification. If  the DME mileage at the intersection is a cumulative distance  of route segments, the mileage is totaled and indicated by  a D-shaped symbol with a mileage number inside  .  [Figure 1-4]  Approved IFR global positioning system (GPS)  units can also be used to report intersections. DME and GPS provide valuable route information concerning  such factors as mileage, position, and ground speed. Even  without this equipment, information is provided on the charts  for making the necessary calculations using time and distance.  The en route chart depicts point-to-point distances on the  airway system. Distances from VOR to VOR are charted with  a number inside of a box  . To differentiate distances when  two airways coincide, the word “TO” with the three-letter VOR  identifier appear to the left of the distance boxes  . VOR changeover points (COPs) are depicted on the charts by  this symbol  . The numbers indicate the distance at which  to change the VOR frequency. The frequency change might  be required due to signal reception or conflicting frequencies.  If a COP does not appear on an airway, the frequency should  be changed midway between the facilities. A COP at an  intersection may indicate a course change. Occasionally an “x” appears at a separated segment of an  airway that is not an intersection. The “x” is a mileage  breakdown or computer navigation fix and may indicate a  course change. the controller may provide the holding direction and the  statement “as published.”  [Figure 1-4] Technological advances have made multifunction displays  and moving maps more common in newer aircraft. Even older  aircraft are being retrofitted to include “glass” in the flight  deck.  [Figure 1-6]  Moving maps improve pilot situational  awareness (SA) by providing a picture of aircraft location  in relation to NAVAIDS, waypoints, airspace, terrain, and  New Technologies Weather Information and Communication Features Other Route Information 1-10 Boundaries separating the jurisdiction of Air Route Traffic  Control Centers (ARTCC) are depicted on charts with blue  serrations  . The name of the controlling  facility is printed on the corresponding side  of the division line. ARTCC remote sites are  depicted as blue serrated boxes and contain  the center name, sector name, and the sector frequency.  [Figure 1-4] En route NAVAIDs also provide weather information and  serve communication functions. When a NAVAID is shown  as a shadowed box, an automated  flight service station (AFSS) of the  same name is directly associated with  the facility. If an AFSS is located  without an associated NAVAID, the  shadowed box is smaller and contains only the name and  identifier. The AFSS frequencies are provided above the  box. (Frequencies 122.2 and 255.4,  and emergency frequencies 121.5 and  243.0 are not listed.) A Remote Communications Outlet (RCO) associated with  a NAVAID is designated by a thin-lined box with the  controlling AFSS frequency above  the box and the name under the box.  Without an associated facility, the  thin-lined RCO box contains the  AFSS name and remote frequency. Station (ASOS), Automated Weather Observing Station  (AWOS), Hazardous Inflight Weather Advisory Service  (HIWAS), and Transcribed Weather Broadcast (TWEB)  are continuously transmitted over  selected NAVAIDs and depicted  in the NAVAID box. ASOS/ AWOS are depicted by a white  “A”, HIWAS by a “H” and TWEB broadcasts by a “T” in a  solid black circle in the upper right or left corner. Automated Surface Observing  Today’s computerized system of ATC has greatly reduced  the need for holding en route. However, published holding  patterns are still found on charts at junctures  where ATC has deemed it necessary to enable  traffic flow. When a holding pattern is charted,  Holding Pattern NAME Name 000.0  000.0