MART Vol. II MO/MP - NESA - Civil Air Patrol

5.5 Electronic Aids to Navigation (Navaids)From the standpoint of a mission aircrew, navigational instruments are themeans to an end. Navigational equipment allows the aircraft to be flown to adesired location, such as a search pattern entry point, with precision andeconomy. Once in the search or assessment area, this equipment allows the pilotto fly the assigned area precisely and thoroughly. Navaids also enable the crewto track their position and record sightings. From the mission staff's viewpoint,proper use of this equipment assures them that the assigned area was actuallyflown -- the only variables left to accommodate are search effectiveness and theinherent limitations of scanning.This section will cover some of the electronic means available that can help innavigating. These systems not only can help you determine your position inreduced visibility or over desolate terrain, but can help you more accurately flysearch and assessment patterns and report your observations to groundpersonnel or to mission base.One drawback to all of this sophisticated equipment is that they may distractthe pilot (and observer) from looking outside of the aircraft. The great majority ofCAP missions are performed in VFR conditions, and the CAP aircrew must notforget the importance of looking where you're going. The best way to avoid thistrap is to become and continue to be very familiar with the operation of thisequipment. Training and practice (along with checklists or aids) allows eachcrewmember to set or adjust instruments with minimum fuss and bother, thusallowing them to return their gaze outside the aircraft where it belongs. Allmembers of the aircrew should be continuously aware of this trap.Additionally, it is important that observers use this equipment to help the pilotmaintain situational awareness. The aircrew should always know the aircraft'sposition on the sectional chart, and these instruments enable them to do so withgreat accuracy.5.5.1 Automatic Direction Finder (ADF)The automatic radio compass, generally known as the Automatic DirectionFinder (ADF), is used to receive radio guidance from stations such as four-courseranges, radio beacons, and commercial broadcast facilities. The automaticdirection finder indicates the direction of the station being received. This directionis shown in relation to the heading of the aircraft. The ADF is the least accurate ofall the navigational instruments.Probably the most common use of the automatic direction finder is in“homing”. The pilot tunes in a desired station, and then flies directly to that stationby keeping the ADF indicating needle on the zero mark. When the needle pointsto the zero mark, the aircraft is headed toward the station. When the station ispassed, the needle will swing around to the 180-degree position, indicating thatthe station is behind.The ADF has three primary components -- a transmitter on the ground, areceiver and an indicator, both in the aircraft. Transmitters include non-directionalradio beacons (NDBs) and commercial AM radio stations. Each transmitter emitsa single signal on a specific frequency in all directions. ADF equipment aboardthe aircraft indicates the relative bearing of the station, or its relative direction from75