Questions Well Answered.
Define and identify, on a diagram of the earth:
(a) great circles; - Answer Great circles are ones whose planes pass through the centre of the earth and
splits the earth into two equal parts, lines of meridians with their anti-meridian form a great circle. The
equator is also a great circle.
Define and identify, on a diagram of the earth:
(b) small circles; - Answer Small circles are circles on the surface on the earth that do not pass through
the centre of the earth. Parallels of latitude other than the equator are all small circles.
Define and identify, on a diagram of the earth:
(c) rhumb lines; - Answer A rhumb line is a regularly curved line on the earths surface that cuts all
meridians at right angles.
Define and identify, on a diagram of the earth:
(d) parallels of latitude; - Answer Parallels of lattitude are small circles (except the equator) that start at
0 deg at the equator and extend to 90 deg N at the north pole and 90 deg S at the south pole.
Define and identify, on a diagram of the earth:
(e) meridians of longitude; - Answer All meridians of longitude are great circles that pass through the
north and south poles as well as the centre of the earth. They start at 000 deg E/W at the prime
meridian and travel to 180 deg E/W at the prime meridians anti-meridian.
Define and identify, on a diagram of the earth:
(f) Greenwich (Prime) Meridian. - Answer The prime meridian is the meridian that runs through
Greenwich and is located at 000 deg E/W.
Define:
,(a) relative bearing; - Answer A relative bearing is the bearing of an object measured clockwise from
the nose of the aircraft.
Define:
(b) back bearing - Answer Back bearing is the reciprocal of the relative bearing which can be found by
adding or subtracting 180 deg.
18.4.4 Explain the processes, cautions and limitations when deriving track distances and
bearings from a chart. - Answer To avoid problems when deriving distances and bearings from charts it
is important to do the following:
- ensure charts are the latest edition
- ensure the correct scale ruler is used for the chart
- align the protractor correctly with lat/long lines
- apply variation correctly
- confirm whether the bearing is 'to' or 'from' an object
18.6.2 Define the various units of distance used in aviation and the application of each.
(a) Nautical mile - Answer A nautical mile is the length of an arc on a great circle that equates to a 1-
minute angle at the earths centre. A 1-degree angles will equate to a 60nm arc.
1 nautical mile equates to:
- 1.15 statute miles
- 6076.12 feet
- 1.85 kilometres
18.6.2 Define the various units of distance used in aviation and the application of each.
(b) Statute mile - Answer Statute miles were decreed by law however have no practical application in
aeronautical navigation. 1 Statute miles equates to:
- 5,280 feet
- 0.87 nautical miles
- 1.6 kilometres
, 18.6.2 Define the various units of distance used in aviation and the application of each.
(c) kilometre - Answer A kilometre is not often used for aeronautical distances. The length of a km is
1/10,000th of the distance between the equator and either pole.
1 kilometre equates to:
- 3,280 feet
- 0.54 nautical miles
- 0.62 statute miles
18.8.2 Define:
(a) a knot (kt); - Answer A unit of airspeed equivalent to 1 nautical mile per hour.
18.8.2 Define:
(c) indicated airspeed (IAS); - Answer The speed value indicated on the airspeed indicator.
18.8.2 Define:
(d) calibrated airspeed (CAS); - Answer The indicated airspeed corrected for instrument error and
pressure error.
18.8.2 Define:
(e) equivalent airspeed (EAS); - Answer The calibrated airspeed correct for compressibility error.
(usually insignificant at low altitudes and speeds)
18.8.2 Define:
(f) true airspeed (TAS). - Answer The actual speed of the aircraft through the air. It is the calibrated
airspeed corrected for air density.
18.8.2 Define:
(b) ground speed (GS); - Answer The speed of the aircraft relative to the ground. This is measured in
knots and indicates the number of nautical miles of ground covered in 1 hour.