Navigation

• Item 8 is the route of flight. If the flight is to be direct, The prefix “omni-” means all, and an omnidirectional range enter the word “direct;” if not, enter the actual route to is a VHF radio transmitting ground station that projects be followed, such as via certain towns or navigation straight line courses (radials) from the station in all directions. aids. From a top view, it can be visualized as being similar to the spokes from the hub of a wheel. The distance VOR radials are • Item 10 is the estimated time en route. In the sample projected depends upon the power output of the transmitter. flight plan, 5 minutes was added to the total time to allow for the climb. The course or radials projected from the station are referenced • Item 12 is the fuel on board in hours and minutes. This to MN. Therefore, a radial is defined as a line of magnetic is determined by dividing the total usable fuel aboard bearing extending outward from the VOR station. Radials are in gallons by the estimated rate of fuel consumption identified by numbers beginning with 001, which is 1° east in gallons. of MN and progress in sequence through all the degrees of a circle until reaching 360. To aid in orientation, a compass rose Remember, there is every advantage in filing a flight plan; reference to magnetic north is superimposed on aeronautical but do not forget to close the flight plan upon arrival. This charts at the station location. should be done via telephone to avoid radio congestion. VOR ground stations transmit within a VHF frequency band Ground-Based Navigation of 108.0–117.95 MHz. Because the equipment is VHF, the Advances in navigational radio receivers installed in aircraft, signals transmitted are subject to line-of-sight restrictions. the development of aeronautical charts that show the exact Therefore, its range varies in direct proportion to the altitude location of ground transmitting stations and their frequencies, of receiving equipment. Generally, the reception range of along with refined flight deck instrumentation make it the signals at an altitude of 1,000 feet above ground level possible for pilots to navigate with precision to almost any (AGL) is about 40 to 45 miles. This distance increases with point desired. Although precision in navigation is obtainable altitude. [Figure 16-28] through the proper use of this equipment, beginning pilots should use this equipment to supplement navigation by visual “A” and “B” signal reference to the ground (pilotage). This method provides the received pilot with an effective safeguard against disorientation in the event of radio malfunction. Only “A” signal received Only “B” signal received There are three radio navigation systems available for use for VFR navigation. These are: Neither “A” nor “B” • VHF Omnidirectional Range (VOR) signal received • Nondirectional Radio Beacon (NDB) • Global Positioning System (GPS) Very High Frequency (VHF) Omnidirectional Range (VOR) The VOR system is present in three slightly different navigation aids (NAVAIDs): VOR, VOR/distance measuring equipment (DME)(discussed in a later section), and VORTAC. By itself it is known as a VOR, and it provides VOR VOR station station magnetic bearing information to and from the station. When “A” “B” DME is also installed with a VOR, the NAVAID is referred to as a VOR/DME. When military tactical air navigation Figure 16-28. VHF transmissions follow a line-of-sight course. (TACAN) equipment is installed with a VOR, the NAVAID is known as a VORTAC. DME is always an integral part of a VORTAC. Regardless of the type of NAVAID utilized (VOR, VOR/DME, or VORTAC), the VOR indicator behaves the same. Unless otherwise noted in this section, VOR, VOR/DME, and VORTAC NAVAIDs are all referred to hereafter as VORs. 16-22