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ATPL Navigation study materials
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ATPL Navigation practice questions

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Question 1Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

The shape of the Earth is best described for navigation purposes as which of the following?

  1. A prolate spheroid elongated at the poles
  2. A perfect sphere of radius 6371 km
  3. An oblate spheroid flattened at the poles Correct answer.
  4. A flat disc with the North Pole at the centre

Explanation

The Earth bulges at the equator and is flattened at the poles because of its rotation, giving an oblate spheroid (ellipsoid). The equatorial radius is about 6378 km and the polar radius about 6357 km, a difference of roughly 21 km. For most chartwork a sphere is an acceptable approximation, but the true figure is the ellipsoid.

Question 2Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

On the Earth's reference ellipsoid, the difference between the equatorial radius and the polar radius is approximately how much?

  1. 21 km Correct answer.
  2. 110 km
  3. 340 km
  4. 2 km

Explanation

The equatorial radius is about 6378 km and the polar radius about 6357 km, so the flattening amounts to roughly 21 km. This corresponds to a flattening ratio of about 1/298. The difference is small relative to the size of the Earth but significant in precise geodetic work.

Question 3Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

A great circle on the Earth's surface is defined as which of the following?

  1. A circle whose plane is parallel to the equator
  2. A line of constant bearing crossing all meridians
  3. Any circle drawn on the surface with a fixed radius
  4. Any circle whose plane passes through the Earth's centre Correct answer.

Explanation

A great circle is formed where a plane through the centre of the sphere cuts the surface, dividing it into two equal halves. Its radius equals the Earth's radius. The shortest path between two points on a sphere always lies along a great circle arc.

Question 4Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Which of the following circles on the Earth's surface is a great circle?

  1. The equator Correct answer.
  2. The parallel of 60°S
  3. The parallel of 45°N
  4. The Tropic of Cancer

Explanation

Only the equator, among parallels of latitude, has its plane passing through the Earth's centre, so it alone is a great circle. All other parallels are small circles whose planes do not contain the centre. The tropics are parallels at about 23.5° and are therefore small circles.

Question 5Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Latitude of a point on the Earth's surface is defined as which of the following?

  1. The angle between the plane of the equator and the radius to the point Correct answer.
  2. The angular distance measured along the equator from Greenwich
  3. The arc of the equator between the prime meridian and the meridian of the point
  4. The angle between the equator and the meridian of the point

Explanation

Geocentric latitude is the angle at the Earth's centre between the equatorial plane and the radius to the point. Geodetic latitude, used on charts, is the angle between the equatorial plane and the normal to the ellipsoid. Both are measured from the equator, positive north or south.

Question 6Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Longitude is measured how, relative to the prime meridian?

  1. From 0° to 360° eastward only on all charts
  2. From 0° to 90° east or west
  3. From 0° to 180° north or south
  4. From 0° to 180° east or west Correct answer.

Explanation

Longitude is the arc of the equator, or the angle at the pole, between the prime meridian and the meridian of the place. It is measured from 0° at Greenwich up to 180° both east and west. Latitude, not longitude, is measured north or south.

Question 7Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

What is the length of one minute of arc of latitude measured along a meridian on the mean spherical Earth?

  1. 1.15 nautical miles
  2. 1 statute mile
  3. 1 kilometre
  4. 1 nautical mile Correct answer.

Explanation

One minute of arc of a great circle subtends one nautical mile, defined as 1852 m. Since meridians are great circles, one minute of latitude equals one nautical mile. The kilometre and statute mile do not correspond to this angular unit.

Question 8Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

A position is given as 30°15'S 045°40'W. What is the latitude expressed in decimal degrees?

  1. 30.25°S Correct answer.
  2. 30.40°S
  3. 30.75°S
  4. 30.15°S

Explanation

Minutes are converted to a decimal fraction of a degree by dividing by 60. Here 15/60 equals 0.25, so 30°15' becomes 30.25°S. The longitude minutes are handled the same way but do not affect latitude.

Question 9Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Two places lie on the same meridian, at 12°N and 37°N. What is the great-circle distance between them?

  1. 25 nautical miles
  2. 250 nautical miles
  3. 2500 nautical miles
  4. 1500 nautical miles Correct answer.

Explanation

The difference in latitude is 25°, and one degree of a great circle equals 60 nautical miles. Multiplying 25 by 60 gives 1500 nautical miles. Because they share a meridian, the separation is purely latitudinal.

Question 10Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

What is the angular distance, in degrees, between the equator and the North Pole?

  1. 45°
  2. 60°
  3. 180°
  4. 90° Correct answer.

Explanation

Latitude is measured from the equator (0°) to the pole, which is at 90°. The full angular distance from pole to pole through the equator is 180°. The 90° figure follows directly from the geometry of the sphere.

Question 11Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

True bearing is measured in which way?

  1. Clockwise from true south, 000° to 180°
  2. Counter-clockwise from true north, 000° to 360°
  3. Clockwise from true north, 000° to 360° Correct answer.
  4. Clockwise from magnetic north, 000° to 360°

Explanation

True bearing is the clockwise angle at the observer from the true north direction to the line to the object. It runs from 000° through 090°, 180°, 270° back to 360°. Magnetic bearing uses magnetic north as reference instead.

Question 12Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

The magnetic variation at a place is 8°W. A magnetic bearing of 120°M corresponds to which true bearing?

  1. 128°T Correct answer.
  2. 132°T
  3. 112°T
  4. 120°T

Explanation

With westerly variation, magnetic north lies west of true north, so true bearing equals magnetic bearing plus westerly variation. Adding 8° to 120° gives 128°T. The rule is often remembered as variation west, magnetic best (magnetic is larger).

Question 13Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

At a place where variation is 12°E, a true bearing of 200°T corresponds to which magnetic bearing?

  1. 200°M
  2. 224°M
  3. 212°M
  4. 188°M Correct answer.

Explanation

With easterly variation, magnetic north lies east of true north, so magnetic bearing equals true bearing minus easterly variation. Subtracting 12° from 200° gives 188°M. This matches the memory aid variation east, magnetic least.

Question 14Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

A rhumb line between two points on the Earth's surface has which property?

  1. It always follows a parallel of latitude
  2. It is always the shortest distance between the points
  3. It is a great circle arc on all charts
  4. It crosses every meridian at the same angle Correct answer.

Explanation

A rhumb line, or loxodrome, maintains a constant angle with every meridian, so it plots as a straight line on a Mercator chart. It is generally longer than the great-circle arc between the same points. Only on the equator or along a meridian do the two coincide.

Question 15Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Which statement correctly compares a great-circle track with a rhumb-line track between two points in the same hemisphere at different latitudes?

  1. Both tracks have constant bearing and equal length
  2. The great-circle track has constant bearing and is longer
  3. The great-circle track is shorter and its bearing changes continuously Correct answer.
  4. The rhumb-line track is shorter and its bearing changes continuously

Explanation

The great-circle arc is the shortest path on a sphere, but its bearing relative to true north changes along the route except at the vertex and equator crossings. The rhumb line keeps a constant bearing but is longer. This trade-off is central to flight planning.

Question 16Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

On a sphere, the shortest surface path between two points always lies along which of the following?

  1. The rhumb line joining them
  2. The parallel of latitude joining them
  3. The meridian passing through the midpoint
  4. The great-circle arc joining them Correct answer.

Explanation

Geodesics on a sphere are great circles, so the shortest surface route between any two points is the shorter arc of the great circle through them. A parallel is not generally a great circle, and a rhumb line is longer except in special cases.

Question 17Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

An aircraft flies due east along the parallel of 60°N for one degree of longitude. What is the approximate ground distance covered?

  1. 60 nautical miles
  2. 52 nautical miles
  3. 15 nautical miles
  4. 30 nautical miles Correct answer.

Explanation

The length of one degree of longitude along a parallel equals 60 nautical miles multiplied by the cosine of the latitude. At 60°N the cosine is 0.5, so one degree of longitude spans about 30 nautical miles. This convergence of meridians is why chart scales vary with latitude.

Question 18Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

The departure between two meridians 10° apart along the parallel of 45°N is closest to which value?

  1. 848 nautical miles
  2. 300 nautical miles
  3. 424 nautical miles Correct answer.
  4. 600 nautical miles

Explanation

Departure equals change of longitude in minutes multiplied by the cosine of the latitude. Ten degrees is 600 minutes, and cos 45° is about 0.707, giving roughly 424 nautical miles. Departure is measured along the parallel, not along a great circle.

Question 19Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

The antipodal point of 25°N 130°E is which of the following?

  1. 25°N 050°W
  2. 25°S 050°E
  3. 25°S 130°W
  4. 25°S 050°W Correct answer.

Explanation

An antipode has the opposite latitude sign and a longitude differing by 180°. The latitude becomes 25°S, and 130°E plus 180° gives 310°, which is 50°W. The result must lie on the opposite side of the Earth in both coordinates.

Question 20Basics of Navigation (form of the Earth, coordinate systems, direction and distance on the sphere)

Two aircraft depart the same point on the equator, one tracking 090°T and the other 090°M, where variation is 10°E. Which statement is correct?

  1. Their tracks differ by 20° of true bearing
  2. Their tracks differ by 90° of true bearing
  3. Their tracks differ by 10° of true bearing Correct answer.
  4. Their tracks are identical because both are due east

Explanation

A true bearing of 090°T and a magnetic bearing of 090°M are referenced to different norths. With 10°E variation the magnetic track corresponds to 080°T, so the true tracks differ by 10°. The reference direction, not the numerical value, determines the actual path.

Question 21Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The angle between true north and magnetic north at a given place is called:

  1. Magnetic dip
  2. Magnetic deviation
  3. Magnetic inclination
  4. Magnetic variation Correct answer.

Explanation

Magnetic variation, also called declination, is the angular difference between the direction of true (geographic) north and the direction of magnetic north at a particular position on the Earth's surface. It is a property of the location and is shown on charts as isogonals.

Question 22Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

In the Northern Hemisphere, the Earth's magnetic lines of force generally point:

  1. Upward and away from the pole
  2. Parallel to the surface everywhere
  3. Straight up at the equator
  4. Downward and toward the magnetic pole Correct answer.

Explanation

In the Northern Hemisphere the magnetic field dips downward toward the magnetic north pole, so a freely suspended magnet tends to tilt with its north-seeking end downward. This downward component is what produces positive dip at northern latitudes.

Question 23Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

A compass needle freely suspended in the Southern Hemisphere will tend to:

  1. Tilt with its north-seeking end downward Correct answer.
  2. Tilt with its north-seeking end upward
  3. Rotate continuously about a vertical axis
  4. Point horizontally with no tilt

Explanation

Because the magnetic lines of force dip upward in the Southern Hemisphere, the north-seeking end of the needle is pulled upward, away from the ground. Dip is therefore negative (needle north end up) at southern magnetic latitudes.

Question 24Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The purpose of the liquid in a direct-reading magnetic compass is to:

  1. Increase the magnetic moment of the needles
  2. Eliminate magnetic deviation entirely
  3. Provide electrical conductivity for the sensing element
  4. Damp oscillation and support the weight of the assembly Correct answer.

Explanation

The compass fluid damps out oscillations of the magnet system and, by buoyancy, relieves the pivot of most of the assembly's weight. This reduces pivot friction and gives steadier readings.

Question 25Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The deviation of a magnetic compass is caused by:

  1. The Earth's magnetic field at the aircraft's position
  2. The rotation of the Earth beneath the compass
  3. Magnetic fields produced by the aircraft itself Correct answer.
  4. The vertical component of the Earth's field only

Explanation

Deviation is the angular error between the magnetic heading and the compass heading, and it arises from magnetic fields generated by the aircraft's structure, engines and electrical equipment. It varies with heading because those fields have fixed directions relative to the airframe.

Question 26Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

On a Direct Reading Compass (DRC), the turning error is greatest when the aircraft is:

  1. Turning through north or south Correct answer.
  2. Accelerating on a northerly heading
  3. Turning through east or west
  4. Flying straight and level at high speed

Explanation

Turning (northerly/southerly) error is largest when turning through headings near north or south, because the compass card tilts about its pivot and the horizontal component of the Earth's field is weakest there. It is zero when turning through east or west.

Question 27Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

An aircraft is heading 090°(M) and the compass reads 084°C. The deviation is:

  1. 6°E Correct answer.
  2. +6° on all headings
  3. 6°W
  4. Zero, because variation has not been applied

Explanation

Deviation is compass heading minus magnetic heading, or equivalently the error of the compass relative to magnetic north. Compass 084 versus magnetic 090 means the compass under-reads, so the compass north lies east of magnetic north: 6°E.

Question 28Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

True heading is 215°, variation is 8°W. The magnetic heading is:

  1. 215°(M)
  2. 8°(M)
  3. 207°(M)
  4. 223°(M) Correct answer.

Explanation

With westerly variation, magnetic north lies west of true north, so magnetic heading is greater than true heading. Adding 8° to 215° gives 223°(M). The rule is: variation west, magnetic best; variation east, magnetic least.

Question 29Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The magnetic heading is 300°(M) and the compass deviation is 5°W. The compass heading is:

  1. 300°C
  2. 305°C Correct answer.
  3. 295°C
  4. 5°C

Explanation

Deviation west means compass north lies west of magnetic north, so the compass heading is greater than the magnetic heading. Adding 5° to 300° gives 305°C. Remember: deviation west, compass best.

Question 30Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

A compass swing is carried out on an aircraft primarily to:

  1. Align the compass with true north
  2. Determine the variation at the airfield
  3. Calibrate the gyromagnetic indicator's rate gyro
  4. Produce a deviation card for each heading Correct answer.

Explanation

A compass swing compares the compass reading with known magnetic headings on a compass base and records the residual deviation for each heading on a deviation card. The card is then used in flight to convert between magnetic and compass headings.

Question 31Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

An aircraft accelerates on a heading of 090°(M) in the Northern Hemisphere. The Direct Reading Compass will momentarily indicate:

  1. A permanent change of deviation
  2. A turn toward the north Correct answer.
  3. A turn toward the south
  4. No change at all

Explanation

Acceleration error occurs on east or west headings; in the Northern Hemisphere, acceleration makes the compass indicate a turn toward north. This happens because the compass card's centre of gravity is below the pivot, so inertia tilts the card and the vertical field component deflects it.

Question 32Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

In the Northern Hemisphere, when rolling out of a turn onto a northerly heading, the Direct Reading Compass will:

  1. Read correctly with no correction
  2. Over-read, so the aircraft must stop before north
  3. Show a permanent easterly deviation
  4. Under-read, so the aircraft must be turned past north Correct answer.

Explanation

Northerly turning error makes the compass lag behind the actual heading during turns through north. On roll-out the compass under-reads, so the aircraft appears to be short of north and must be turned slightly past the desired heading.

Question 33Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The component of the Earth's magnetic field that actually aligns the compass needle is the:

  1. Horizontal component Correct answer.
  2. Vertical component
  3. Total field strength
  4. Angle of dip

Explanation

A compass needle constrained to rotate in the horizontal plane responds only to the horizontal component of the Earth's field. The vertical component causes dip and the tilting errors, but does not provide the directive force in azimuth.

Question 34Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

The isogonals drawn on an aeronautical chart join points of:

  1. Equal annual change of variation
  2. Equal magnetic dip
  3. Equal magnetic variation Correct answer.
  4. Zero magnetic variation

Explanation

Isogonals are lines of equal magnetic variation, and the chart annotations give the variation value and its annual rate of change. They allow the pilot to update variation for the year of flight.

Question 35Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

At the magnetic equator, a freely suspended magnetic needle will:

  1. Show maximum dip
  2. Remain horizontal Correct answer.
  3. Stand vertically
  4. Point toward the geographic pole

Explanation

At the magnetic equator the vertical component of the Earth's field is zero, so dip is zero and the needle lies horizontally. Dip increases toward the magnetic poles, where the needle would stand vertically.

Question 36Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

An aircraft flies on a compass heading of 120°C. Deviation is 3°E and variation is 10°W. The true heading is:

  1. 113°(T) Correct answer.
  2. 107°(T)
  3. 127°(T)
  4. 133°(T)

Explanation

Convert compass to magnetic by applying easterly deviation: magnetic equals compass plus 3°, giving 123°(M). Then apply westerly variation by subtracting 10°, giving 113°(T).

Question 37Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

Which statement about a remote-reading (flux valve) compass system is correct?

  1. The flux valve senses the horizontal component of the Earth's field and feeds a gyro-stabilised display Correct answer.
  2. The system needs no deviation correction because it is gyro-stabilised
  3. The flux valve directly displays the magnetic heading on a wet compass card
  4. The detector unit must be mounted on the aircraft's longitudinal axis

Explanation

A remote-reading system uses a flux valve detector, usually in a wingtip, to sense the horizontal component of the Earth's field and transmits this to a gyro-stabilised indicator. The gyro provides short-term stability while the flux valve supplies the long-term magnetic reference.

Question 38Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

A remote-reading compass with a flux valve is preferred over a direct-reading compass mainly because it:

  1. Eliminates all magnetic errors automatically
  2. Requires no electrical power
  3. Works without any magnetic sensing element
  4. Reduces turning and acceleration errors and gives a steadier, more readable display Correct answer.

Explanation

The gyro-stabilised indicator smooths out the short-term turning and acceleration errors that affect a wet compass, giving a steady, easily read heading. The flux valve also senses the field remotely, away from airframe disturbances.

Question 39Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

In the Northern Hemisphere, a Direct Reading Compass on a northerly heading is disturbed by a sudden deceleration. The compass will momentarily indicate:

  1. A permanent deviation change
  2. A turn toward the west Correct answer.
  3. No change
  4. A turn toward the east

Explanation

On a northerly heading, acceleration error in the Northern Hemisphere makes the compass indicate a turn toward the east, and deceleration produces the opposite, an apparent turn toward the west. This is because the inertia of the card tilts it and the vertical field component deflects it.

Question 40Magnetism and Compasses (terrestrial magnetism, variation, deviation, direct and remote-reading compasses)

A Direct Reading Compass is checked on a compass base. The readings show a maximum deviation of 2° and it repeats consistently on both clockwise and counter-clockwise swings. This indicates:

  1. Excessive friction in the pivot and a faulty compass
  2. A satisfactory compass with an acceptable residual deviation card Correct answer.
  3. A mis-set variation setting on the instrument
  4. That the flux valve needs replacement

Explanation

A small residual deviation that repeats consistently on both swing directions shows the compass is behaving correctly and is free from excessive pivot friction. The residual values are simply recorded on the deviation card for use in flight.

Question 41Charts (projections, properties, practical use of aeronautical charts)

On a Lambert conformal conic chart, which property is preserved at every point?

  1. Areas of all land masses
  2. Distances along all meridians
  3. Great circles as straight lines
  4. Angles between intersecting lines Correct answer.

Explanation

A conformal projection preserves local angles, so shapes of small features remain correct. Scale error is the same in all directions at a point, though it varies across the chart. Areas and distances are therefore not preserved globally.

Question 42Charts (projections, properties, practical use of aeronautical charts)

What is the principal advantage of the gnomonic projection for flight planning?

  1. Scale is constant across the whole chart
  2. It preserves true area everywhere
  3. All great circles plot as straight lines Correct answer.
  4. It shows both poles without distortion

Explanation

On a gnomonic chart the plane touches the sphere at a single point and every great circle projects as a straight line. This allows a planned route to be drawn directly and the great-circle track to be measured easily. Scale and shape distortion increase rapidly away from the point of tangency.

Question 43Charts (projections, properties, practical use of aeronautical charts)

On a Mercator chart, what does a straight line drawn between two points represent?

  1. A line of equal magnetic variation
  2. A line of constant latitude
  3. A rhumb line of constant track Correct answer.
  4. A great circle of shortest distance

Explanation

The Mercator projection is constructed so that all rhumb lines appear straight. A straight line therefore represents a constant true track, which is not usually the shortest path. The great circle between the same points curves toward the pole.

Question 44Charts (projections, properties, practical use of aeronautical charts)

In a polar stereographic chart used for navigation near the pole, where is the scale exactly correct?

  1. At every point, because the projection is conformal
  2. At the standard parallel where the cone or plane cuts the sphere Correct answer.
  3. Along the equator, which forms the chart boundary
  4. At the pole itself, where all meridians meet

Explanation

Scale is true only where the projection surface intersects the sphere, that is at the standard parallel. Elsewhere the scale factor departs from unity while local angles remain correct. The pole is a point of extreme convergence, not a line of true scale.

Question 45Charts (projections, properties, practical use of aeronautical charts)

What does a scale of 1:500 000 mean on an aeronautical chart?

  1. One unit on the chart represents 500 000 of the same units on the ground Correct answer.
  2. The chart is valid for flights up to 500 000 feet
  3. The chart covers an area of 500 000 square kilometres
  4. One centimetre on the chart represents 500 000 metres on the ground

Explanation

A representative fraction compares chart length to ground length in the same units. Thus 1 cm on the chart represents 500 000 cm, or 5 km, on the ground. The fraction is dimensionless and independent of the unit chosen.

Question 46Charts (projections, properties, practical use of aeronautical charts)

Which chart is normally used as the basis for dead reckoning and visual navigation in the cruise?

  1. The 1:500 000 topographical aeronautical chart Correct answer.
  2. The 1:250 000 approach chart
  3. The polar stereographic chart
  4. The gnomonic plotting chart

Explanation

The 1:500 000 chart shows enough topographical and airspace detail for visual reference and dead reckoning over long legs. Larger-scale charts cover too small an area for cruise use. Gnomonic charts are used for great-circle plotting rather than visual navigation.

Question 47Charts (projections, properties, practical use of aeronautical charts)

A chart has a scale of 1:250 000. What ground distance is represented by 8 cm measured on the chart?

  1. 2 km
  2. 200 km
  3. 32 km
  4. 20 km Correct answer.

Explanation

At 1:250 000, one centimetre represents 250 000 cm, which is 2.5 km. Multiplying by 8 cm gives 20 km on the ground. The calculation must keep units consistent throughout.

Question 48Charts (projections, properties, practical use of aeronautical charts)

Why does the scale of a Lambert conformal conic chart vary with latitude?

  1. The chart is drawn on a flat sheet of paper
  2. Meridians converge toward the pole
  3. Magnetic variation changes with latitude
  4. The cone cannot be tangent to the sphere along every parallel at once Correct answer.

Explanation

A cone touches the sphere along one or two standard parallels only, so scale is exact there and departs from unity elsewhere. The error is small between the standard parallels and grows toward the edges. Meridian convergence is a separate geometric effect.

Question 49Charts (projections, properties, practical use of aeronautical charts)

On a Mercator chart at latitude 60 degrees, how does the chart scale compare with the scale at the equator?

  1. It is reduced by a factor of about two
  2. It is enlarged by a factor of about four
  3. It is the same as at the equator
  4. It is enlarged by a factor of about two Correct answer.

Explanation

The Mercator scale factor equals the secant of the latitude, so at 60 degrees it is about 2. Features are therefore stretched east-west and north-south by the same ratio, which keeps the projection conformal. Distances measured at high latitude must be corrected for this enlargement.

Question 50Charts (projections, properties, practical use of aeronautical charts)

What is the purpose of a graticule on an aeronautical chart?

  1. To allow positions to be read in latitude and longitude Correct answer.
  2. To indicate the magnetic variation at each point
  3. To give terrain elevation in metres
  4. To show the boundaries of controlled airspace

Explanation

The graticule is the network of meridians and parallels printed on the chart. It provides the reference framework for determining latitude and longitude of any point. Airspace boundaries and terrain elevations are shown by separate overprints and colouring.