ATPL Navigation Exam Questions and Answers Already Passed
Navigation at High Latitudes - Answers At high latitudes, there are also cautions you need to be aware of
when using charts to navigate. As you will soon see, Mercator charts are not accurate above 70°N or S.
This is due to the charts becoming distorted, which compromises the accuracy of the data on the charts.
Lambert's conformal projection charts are commonly used at mid latitudes, where they are far more
accurate than the Mercator charts.
When navigating at the poles, you have the problem of all the meridians converging at one point. To
solve this, polar charts (also known as polar grids) are used. These form the shape of the spokes of a
bicycle wheel
Great Circles - Answers The great circles are the imaginary lines that run through the centre of the Earth.
Hypothetically, they are lines that split the Earth in half.
The great circles have the following properties:
They are the largest circles that can be drawn on the surface of a sphere.
Radio waves follow the path of a great circle.
The only parallel of latitude, which is a great circle, is the equator.
All meridians of longitude are half of a great circle. (e.g., 0° meridian and the 180° meridian make a great
circle).
REMEMBER THIS: The shortest distance between two points on the surface of a sphere is the arc of a
great circle.
Small Circles - Answers The small circles are all imaginary circles on a sphere that don't cut the Earth into
two equal portions. Hypothetically, they are circular segments.
, All parallels of latitude are small circles except for the equator, which is a great circle.
Rhumb lines - Answers A rhumb line is a line that crosses all meridians of longitude at the same angle. It
is not the shortest distance between two points.
When you are flying along a rhumb line, your direction is constant. However, when you are flying along a
great circle, your direction is constantly changing.
On short-haul flights, the distance between a rhumb line and a great circle is negligible. It is easier to fly
the rhumb line, where your heading is constant.
On long-haul flights, it is common to fly a great circle, where the distance between two points is much
shorter. This is where you would get obvious cost-saving benefits.
Equator - Answers The equator is the imaginary east-to-west line that divides the Earth into two equal
portions or hemispheres, known as the northern hemisphere and the southern hemisphere.
The equator is the prime parallel of latitude and is a great circle.
Meridians of longitude - Answers The prime method for pinpointing a position on the Earth's surface is
to use latitude and longitude coordinates. The Earth is divided into 360 degrees of longitude (0-180
degrees west, 0-180 degrees east) and 180 degrees of latitude (0-90 degrees north, 0-90 degrees south).
The meridians of longitude are the vertical lines you see on a diagram (or map) of the Earth. Each
meridian has an anti meridian, which is just the opposite meridian, e.g., 30°E has an anti meridian of
150°W.
All meridians of longitude are great circles (meridian + anti meridian = great circle), e.g., meridian 30°E
(+30) combined with its anti meridian, 150°W (-150).
Navigation at High Latitudes - Answers At high latitudes, there are also cautions you need to be aware of
when using charts to navigate. As you will soon see, Mercator charts are not accurate above 70°N or S.
This is due to the charts becoming distorted, which compromises the accuracy of the data on the charts.
Lambert's conformal projection charts are commonly used at mid latitudes, where they are far more
accurate than the Mercator charts.
When navigating at the poles, you have the problem of all the meridians converging at one point. To
solve this, polar charts (also known as polar grids) are used. These form the shape of the spokes of a
bicycle wheel
Great Circles - Answers The great circles are the imaginary lines that run through the centre of the Earth.
Hypothetically, they are lines that split the Earth in half.
The great circles have the following properties:
They are the largest circles that can be drawn on the surface of a sphere.
Radio waves follow the path of a great circle.
The only parallel of latitude, which is a great circle, is the equator.
All meridians of longitude are half of a great circle. (e.g., 0° meridian and the 180° meridian make a great
circle).
REMEMBER THIS: The shortest distance between two points on the surface of a sphere is the arc of a
great circle.
Small Circles - Answers The small circles are all imaginary circles on a sphere that don't cut the Earth into
two equal portions. Hypothetically, they are circular segments.
, All parallels of latitude are small circles except for the equator, which is a great circle.
Rhumb lines - Answers A rhumb line is a line that crosses all meridians of longitude at the same angle. It
is not the shortest distance between two points.
When you are flying along a rhumb line, your direction is constant. However, when you are flying along a
great circle, your direction is constantly changing.
On short-haul flights, the distance between a rhumb line and a great circle is negligible. It is easier to fly
the rhumb line, where your heading is constant.
On long-haul flights, it is common to fly a great circle, where the distance between two points is much
shorter. This is where you would get obvious cost-saving benefits.
Equator - Answers The equator is the imaginary east-to-west line that divides the Earth into two equal
portions or hemispheres, known as the northern hemisphere and the southern hemisphere.
The equator is the prime parallel of latitude and is a great circle.
Meridians of longitude - Answers The prime method for pinpointing a position on the Earth's surface is
to use latitude and longitude coordinates. The Earth is divided into 360 degrees of longitude (0-180
degrees west, 0-180 degrees east) and 180 degrees of latitude (0-90 degrees north, 0-90 degrees south).
The meridians of longitude are the vertical lines you see on a diagram (or map) of the Earth. Each
meridian has an anti meridian, which is just the opposite meridian, e.g., 30°E has an anti meridian of
150°W.
All meridians of longitude are great circles (meridian + anti meridian = great circle), e.g., meridian 30°E
(+30) combined with its anti meridian, 150°W (-150).
