PPL 12 Navigation

Canadian Private and Recreational Pilot Navigation and Radio Navigation Manual

Geographic co-ordinates provide a means of specifying a location anywhere on the earth’s surface using degrees longitude—also referred to as meridians of longitude—and degrees latitude—also referred to parallels of latitude. Parallels of latitude remain parallel with the equator; meridians of longitude converge at the north and south poles.[2] Meridians of longitude have values between 0 and 180 that are measured east and west of prime meridian located in Greenwich, UK; parallels of latitude have values between 0 and 90 that are measured north and south of the equator. Accordingly, geographic co-ordinates must always have a north/south and east/west reference.

[2] You can remember which is which by noting there are two “Ts” in “latitude”—the “Ts” are parallel.

Each degree, whether longitude or latitude, is divided into 60 minutes (60’), and each minute is divided into 60 seconds (60”). One nautical mile is equal to 1 minute of latitude, but note that this does not apply to longitude as the distance between degrees of longitude change (except along the Equator) with convergence at the poles. Occasionally, chart references use the decimal formal so that 60.25° equals 60° and 15’.

The sun travels 360° longitude in 24 hours, 15° in one hour, 15’ longitude in one minute, and 15” longitude in 1 second time.

There are two lines that can be drawn on a map—a great circle, which cuts the sphere (earth) in two and represents the shortest distance between two points; a rhumb line which is a curved line that cuts all meridians at the same angle. Great circle routes are flown during long distance flights (headings have to be periodically modified). Whether a line on a map is a great circle route or a rhumb line depends on the type of chart used (discussed below).

Heading (sometimes referred to as bearing) refers to the direction the aircraft is pointed. Direction, in turn, is expressed in relation to the north—360°—measured in clockwise fashion. Accordingly, the direction of east is 090°, south is 180°, and west is 270°, etc.

Track refers to the direction the aircraft travels (line) across the earth’s surface, also measured relative to north in clockwise fashion.

Magnetic track (or magnetic heading) refers to a track (or heading) along the ground measured relative to magnetic north.

True track (or true heading) is the same as magnetic track, except that it is measured relative to true north.

Magnetic Variation: the angle between the true north (meridian) and the magnetic north (meridian) aligned with a compass.

Isogonic lines are lines on maps joining areas of equal magnetic variation.

To convert degrees true to magnetic, subtract easterly variation (“east is least”) and add westerly variation (“west is best”).

In contrast, relative bearing is the direction of object relative to the nose of the aircraft (i.e., its longitudinal axis). An object directly in front of the nose of the aircraft has a relative bearing of 360°, etc.

Lubber line refers to the line of the magnetic compass that is fixed and aligned with the longitudinal axis of the aircraft.

Magnetic Compass

The compass is mounted usually in acid-free kerosene that dampens movement.

There are two primary errors associated with a compass: compass deviation and magnetic dip.

Compass deviation is deviation errors of the compass caused by the aircraft’s magnetic fields. It is checked regularly as part of aircraft maintenance. Effects of deviation are minimized by “corrector magnets” attached to the compass housing, while the remaining deviation errors are recorded and displayed in the cockpit on the compass deviation card.

Headings flown by the pilot are corrected for magnetic variations and for compass deviation.

The compass also has errors because of magnetic dip. At the earth’s equator, magnetic lines run parallel to the earth’s surface, but towards the north and south poles, the lines “dip” towards the surface and gradually become vertical. To minimize this effect, the compass is mounted as a pendulum (“pendulous mounting”), but two errors remain related to magnetic dip: Northerly Turning Error, and the Acceleration/Deceleration Error.

The Northerly Turning Error occurs during shallow turns through southerly and northerly headings. As a rule, the compass “leads” when turning from southerly headings, and “lags” when turning from northerly headings. There is approximately no turning error when turning east and west headings.

The Acceleration/Deceleration Error occurs on easterly and westerly headings whereby acceleration causes the compass to show a northerly error, and deceleration causes a southerly error. Remember this by “ANDS.” There is approximately no such error on northerly and southerly headings.

Aviation Charts

There are two types of charts used by pilots: VFR Navigation Charts (VNC) and World Aeronautical Charts (WAC); the former have a scale of 1:500,000, and the latter have a scale of 1:1,000,000. Both are a Lambert Conformal Conic Development (type of chart) whereby the angles between the meridians and parallels will be the same on the map as they are on the ground;[1] accordingly, for practical purposes, a straight line drawn between two points represents a great circle route.

[1] The chart “conforms” with what is on the ground.

To elaborate, a great circle route drawn between two points does not intercept meridians of longitude or parallels of latitude at the same angle (since the earth is a sphere). For this reason, when plotting a straight-line course on a Lambert Conformal chart, the direction relative to true north must be measured at the mid-track position.[2] In contrast to great circle routes are rhumb lines, which intercept meridians and parallels at the same angle; rhumb lines would appear on a type of chart projection referred to as a Transverse Mercator Development where meridians of longitude are projected as parallel—in actuality, of course, they are not.

[2] The line plot actually represents the average direction of the course, since the angles of the meridians and parallels vary.

The third type of aviation chart commonly used by pilots—the VFR Terminal Area Chart (VTA)—is a Transverse Mercator chart. It is published for larger Canadian airports (e.g., Vancouver, Edmonton, Calgary, and Toronto).[3] On VTA charts, the scale is 1:250,000— ½ the scale of the VNC charts.

[3] Because VTAs cover a relatively small area, conformity with the spherical nature of the earth’s surface is not crucial.

Reading the VNC

It is crucial that pilots become extremely familiar with map reading; spend lots of time getting to know the symbols and depictions on the map cover—basically the same for WAC and VNC publications.

Currency

Always ensure that the map used is current; this can be done by checking the date that appears on the front map cover near the top. On the Vancouver VNC current at the time of writing, for example, it states 12th Edition Aeronautical Information May 2000. To determine if this is the current, compare it with the Current Canadian Aeronautical Charts listed on the government website—http://sat.nrcan.gc.ca/ (under Produces and Services).

Highest Elevation Points

From the back cover of the map, the location of highest elevation on the chart in the Hypsometric Tints and Elevation Information—in this case, the highest point is located at 51° 22’ North Latitude, and 125° 16’ West Longitude. Note that degrees latitude and longitude are marked by black indexed lines, with longitude read horizontally, and latitude read vertically.

Additionally, note on the map that box patterns appear on the map in 30 minute intervals of longitude and latitude; these boxes are referred to as a “quadrangles” and in the middle of each quadrangle appears “Maximum Elevation Figure” in blue ink—this figure represents the highest quadrangle terrain elevation plus 328 feet (100m).

Airspace and the VNC

Note that all areas bounded by shaded boundaries indicate controlled airspace (depicted to the right is the airspace around Fort Simpson Airport, NWT, right).[1] Based on knowledge of Canadian airspace structure, we can be certain that controlled airspace within these boundaries always exists at 12,500’ and above (this is Class B airspace and cannot be entered without a clearance). The lower base of the controlled airspace, and its class (whether C, D, or E), however, can be variable.

[1] Being able to read airspace data on a chart is a crucial pilot skill, and you want to take the time to study this carefully on both the VNC and VTA.

To find the base and its class, we must locate a depiction in blue ink somewhere within a specific boundary. Importantly, if the base of airspace is not specified, the base is at 2,200 feet AGL—this is the case, for example, on all airways (routes drawn on the map between radio navigation transmitters).

Finally, note that jagged blue-inked lines denote the boundary of controlled airspace with different floors. Accordingly, surrounding the Fort Simpson’s Control Zone is transition area where the Class E is “floored” at 700 AGL—see right.

As discussed earlier, entry into Class E low-level controlled airspace (controlled airspace below 12,500’ which is not a control zone) does not require a clearance; instead entry by VFR aircraft is simply prohibited if the weather is below the required minimum of VFR aircraft in controlled airspace.

FSS Communication

Flight Service Stations provide all in-flight information to aircraft, but of course communication with a FSS is, for the most part, possible only in VHF “line of sight” range. It is important to know where and how to contact FSS, and this is determined by two means.

Firstly, there are Remote Communication Outlets (RCO) located at various locations—they are, however, not that common. RCO depictions on the map consist of box, usually joined by a line to the transmitter/receiver site. The box contains the name of the RCO, which is based on its location. Above the name box is the VHF frequency to be used, and below the name box is a a second “half box” where the name of the FIC managing the RCO is named. When using an RCO, a pilot calls the named FIC and gives the location of the RCO—“Pacific Radio, this is GABC at Puntzi Mountain on frequency 126.7.” Pacific Radio is the name of the FIC managing the Puntzi Mountain RCO

With respect to the Williams Lake RCO depicted above, the frequency 123.275 MHz is to be used to contact Pacific Radio (the FIC), and the frequency 126.7 MHz is simply used by the FIC to broadcast SIGMET reports (significant weather), or critical PIREP (pilot reports)—“bcst” meaning “broadcast only”. The FIC will also utilize 126.7 when conducting a communications search for a aircraft, but routine RCO communications, such as position reporting or weather updating, are done on the 123.275. When the frequency is depicted as in the case of the Williams Lake RCO, 123.275 is said to be a FISE frequency—Flight Information Service En Route.

The second means of determining FSS communication is by examining the navigation aid data boxes. If the FSS is located in close proximity to the navigation aid, the data box for the aid appears in a thick blue-lined box; if the navigation aid appears in a box bound by a thin blue line, communication with FSS is not possible unless a “half box” appears below the data box. The two examples of this are presented to the right, in the case of the Lethbridge VOR (YQL), and the Fort McMurrey VOR (YMM). Where the half-box is displayed, or in the case of a thick blue-lined box, communication with the named flight service authority is possible using the frequencies listed above the navigation aid box—in the case of the Fort McMurray VOR, the authority is Edmonton Radio. In the case of Lethbridge, the authority is Lethbridge Radio.

In examining the frequencies above the thick blue-lined data box, remember that the standard frequencies of 126.7 and 121.5 MHz can be used even though they are not displayed; they cannot be used when they appear “barred” (a line though the frequency) above the data box. In the case of the thin blue line, 126.7 MHz is used for Flight Information Centre (FIC) broadcasting only.

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PACELINE PILOT TRAINING

Canadian Private and Recreational Pilot Navigation and Radio Navigation Manual

Table of Contents

NAVIGATION

RADIO NAVIGATION

Index

Terms and Concepts

Magnetic Compass

Aviation Charts

Reading the VNC

Currency

Highest Elevation Points

Airspace and the VNC

FSS Communication

Canadian Private and Recreational Pilot Navigation and Radio Navigation Manual

Table of Contents

NAVIGATION

RADIO NAVIGATION

Index

Terms and Concepts

Magnetic Compass

Aviation Charts

Reading the VNC

​

​

Currency

Highest Elevation Points

Airspace and the VNC

FSS Communication