Private Pilot | Lesson 7 - Navigation Systems and Equipment

TABLE OF CONTENTS:
7.1 LONGITUDE AND LATITUDE
7.2 USING VOR RADIALS TO DETERMINE LOCATION
7.3 VORS AND VOR TEST FACILITY (VOT)
7.4 GLOBAL POSITIONING SYSTEM
7.5 AUTOMATIC DIRECTION FINDER (ADF)
7.6 VHF/DIRECTION FINDER FACILITY
7.7 AIRCRAFT TRANSPONDER

7.1 Longitude and Latitude

Any location can be pin-pointed by its longitude and latitude. Lines of latitude and longitude are printed on aeronautical charts (e.g., sectional) with each degree subdivided into 60 equal segments, or "minutes." By referring to your sectional chart, the location of your airport can be easily determined by the intersection of lines of latitude and longitude.

Lines of latitude are parallel to the equator; those north of the equator are indicated as 0° to 90° North latitude, those south of the equator are indicated as 0° to 90° South latitude. (As a pilot flying in the US, it's fair to assume that you'll primarily be operating in the Northern latitudes.)

Lines of longitude are lines which extend from the north pole to the south pole. The prime meridian (which passes through Greenwich, England) is 0° longitude with 180° on both the east and west sides of the prime meridian.

7.2 Using VOR Radials to Determine Location

There will be several exam questions that will require you to identify your location based on the intersection of two given VOR radials.
To locate a position based on VOR radials, draw the radials on your chart or on the plastic overlay during the FAA knowledge test.

Remember that radials are FROM the VOR, or leaving the VOR.

Make sure you have located the correct radial on the compass rose before drawing your line. Double-check yourself by counting in 5° or 10° intervals from each of the closest 30° intervals that are numbered and marked with an arrow.

Other FAA exam questions require you to identify your position based upon the indications of a single VOR.

7.3 VORs and VOR Test Facility (VOT)

Certain airports have VOR Test Facilities (VOTs). These are facilities that transmit radio signals on certain discrete frequencies, allowing you to check the accuracy of your aircraft's VOR receiver while you are on the ground.

To utilize the VOT simply tune your aircraft's VOR to the specified VOT frequency, and use the OBS knob to center the course deviation indicator needle.

Regardless of your position or heading at the airport, the OBS should read either:

• 180° and TO on the TO/FROM indicator. Or,
• 0° and FROM on the TO/FROM indicator.

NOTE: Accuracy of the VOR must be within ±4°.

7.4 Global Positioning System

The use of GPS (or, Global Positioning System) is becoming more and more prevalent in general aviation as a means of navigation. Many newer general aviation aircraft come factory-equipped with GPS navigation systems, and every month it seems there is a new portable GPS available on the market.

The Global Positioning System (GPS) is composed of a constellation of 24 satellites, placed in designed orbits that allow for at least five satellites to be in constant line-of-sight by a user anywhere on earth.

However, a GPS receiver needs only four satellites to yield a three-dimensional position (latitude, longitude, and altitude) and time solution.

GPS receivers are able to compute navigational solutions such as distance and bearing to waypoints (e.g., an airport), or groundspeed, etc., by using the airplane's known latitude/longitude (position) and referencing this to a database built into the receiver.

7.5 Automatic Direction Finder (ADF)

Another type of navigational instrument found in aircraft is the Automatic Direction Finder, or ADF. The ADF is an instrument that works in conjunction with a ground-based nondirectional beacon, or NDB. The ADF functions simply by always having its need point directly toward the NDB to which the instrument is tuned to.

• For example, if the NDB is directly in front of the airplane, the needle will point straight up.
• If the NDB is directly off the right wing, i.e., 3 o’clock, the needle will point directly to the right.
• If the NDB is directly behind the aircraft, the needle will point straight down, etc.

There are a few specific terms used when referencing navigation or instrument flying by the use of the ADF/NDB. The figure below should help to illustrate these terms. (When working ADF problems, it is often helpful to draw the information given - just like the figure below - to provide a picture of the airplane's position relative to the NDB station.)

• Relative bearing TOthe station is shown by the head of the needle.
  • In the figure below, the RB to the station is 220°.
• Relative bearing FROMis given by the tail of the needle.
  • In figure below, the RB from the station is 40° (220 – 180).

Now, there are basically two types of ADFs that can be found in general aviation aircraft, the fixed card ADF and the movable card ADF.

With a fixed card ADF, 0° will always be shown at the top of the instrument.

So, on a fixed card ADF the Relative Bearing may be read directly from the card, and it is the Magnetic Bearing that must be calculated using the above formula.

If the MB is given, the MH may be calculated as follows: MB – RB = MH.

With a movable card ADF, magnetic heading (MH) will always be shown at the top of the instrument.

So, on a movable card ADF the MB TO the station may be read directly from the card under the head of the indicator needle. And, MB FROM will be indicated by the tail of the needle.

RB may be calculated as follows: MB - MH = RB.

7.6 VHF/Direction Finder facility

The VHF/Direction Finder facility is a ground operation that can determine the magnetic direction of an airplane from the station each time the airplane transmits a signal to it. An air traffic controller can then give aid in the form of directional guidance to the aircraft. In order to take advantage of VHF/DF radio reception for assistance in locating a position, an airplane must have both a VHF transmitter and a receiver. The transmitter and receiver are necessary to converse with a ground station having VHF/DF facilities.

In the Airport/Facility Directory the letters "VHF/DF" appearing next to certain airports indicate that the Flight Service Station has VHF/Direction Finding equipment with which to determine your direction from the station.

7.7 Aircraft Transponder

Aircraft transponders transmit specific codes that allow air traffic controllers to identify and track specific aircraft.

1200 is the standard VFR transponder code. When operating under VFR below 18,000 ft MSL, the transponder code 1200 should be selected, unless otherwise instructed by ATC. Similarly, if ATC advises, "Radar service is terminated," the transponder should be set to code 1200.

The following codes are for use during aircraft emergencies only. Additionally, as they cause certain immediate responses from ATC, when making routine transponder code changes, pilots should avoid inadvertent selection of the following codes.

• 7700 -- General emergency
• 7600 -- Lost radio communications
• 7500 -- Hijacked aircraft
• 7777 -- Military interceptor code

Lesson 7 - Navigation Systems and Equipment eFlash Cards

Lesson 7 - Navigation Systems and Equipment Study Quiz