Additional Types of Navigation

ADDITIONAL TYPES OF NAVIGATION

To assist the aviator in the DR process, there are two additional types of navigation: visual

and electronic. It is important to understand that these are aids available to the aviator in

the DR process and do not relieve the Warrior-Aviator of his responsibility to keep a good

DR plot.

Visual Navigation requires maintaining direct visual contact with the earth's surface.

Visual navigation supports DR by using ground references to determine current position or

to provide steering cues to a destination. Visual navigation is most commonly used for

helicopter operations and for high speed/low level flight by tactical aircraft. Its obvious

limitation is that it requires sufficient visibility and visual references. Visual navigation is not

a stand-alone form of navigation. Without DR, the aviator is likely to misidentify ground

references and become lost.

Electronic Navigation requires the use of electronic devices to determine position. They

can be grouped into three general categories. In the first category, electronic signals are

received from ground stations (VOR, TACAN, ADF, OMEGA/VLF). The second category of

electronic devices will transmit their own signals (RADAR, DOPPLER). The last group is

self-contained and requires the aviator to input the starting location (INERTIAL

NAVIGATION SYSTEM or INS). The INS is a high speed DR computer that does the same

thing the aviator does but faster and with greater accuracy. The newest addition to the

electronic navigation family is the Global Positioning System (GPS). This system is similar

to OMEGA but receives its input from space-based satellites. The discussion of electronic

navigation for this class will be limited to TACAN.

TACTICAL AIR NAVIGATION (TACAN)

A TACAN is a ground-based system that provides the aviator with precise position

information. Position is determined by providing the distance (in NM) away and by giving

the magnetic bearing (radial) from the station. Since the TACAN station is at a known

geographic location, the aircrew will be able to determine their position above the earth's

surface via their relationship to the station. The procedures for this are covered in detail in

Lesson Topic 4.2.

A TACAN station operates in the 962 to 1213 MHz frequency range with the individual UHF

frequencies being assigned to a channel. These channels number 1 to 126 with a sub-

designation of "X" or "Y". Each TACAN emits 360 unique signals that are carefully

calibrated to magnetic north and radiate out from the station. These radials look similar to

the spokes of a wheel (Figure 4.1-5). The radial that the aircraft is currently on and the

distance from the station are displayed in the cockpit allowing the aircrew to "fix" their

position.

4.6-14