Navigation Flashcards
What is the polar axis?
Axis of rotation
Two points where this axis meets surface of sphere
What is true north?
Two points where axis meets surface of sphere
If you stand anywhere on earth and face toward the north geographic pole, which way are you facing?
True north
What is a great circle?
Plane which passes through the centre of the sphere (earth)
The largest circle that can be drawn on the surface of the earth
What are three examples of great circles?
Meridian of longitude
Equator
Horizontal paths of radio waves
What is the arc of the great circle?
The shortest distance around surface of sphere between two points
What is the reference point for latitude?
Equator
What is latitude?
Angular distance in degrees from equator measured at centre of earth.
Great circle with plane perpendicular to polar axis
What is a parallel of latitude?
Joins all points of same latitude
What is meridian of longitude?
Great circles containing polar axis (passes through north and south geographic pole)
Meridians of longitude are specified by what?
Difference in degrees east or west from meridian of longitude
What is a rhumb line?
Track for which direction remains constant when referred to true north
What is true direction?
Measure direction by reference to local meridian, using north geographic pole or true north
What is the advantage of true direction?
Constant directional reference
What is variation?
Angular difference between true north and magnetic north
What is magnetic direction?
Line of magnetic force that influences direction of compass
Actual direction pointing to earths north magnetic pole
What are isogonals (or isogonic lines)?
Lines drawn on charts joining all places having same magnetic variation
What is relative bearing?
Angular distance from aircrafts heading measured clockwise from nose of aeroplane
One nautical mile is equal to what?
One minute of latitude
What charts can be joined exactly east/west?
WAC chart
Can two WAC charts be joined exactly north/south? Why/why not?
No
The charts have different standard parallels
If B is due east of A in the southern hemisphere then what happens to a flight which followed the rhumb line track?
A flight which followed the rhumb line track from A to B would diverge to the left of the straight line drawn on the WAC chart
Two WAC charts can be joined east to west because?
They are projections from the same cone
An aircraft which tracks along the 030 omni radial from a station
Follows a great circle path
Direction on a WAC chart should be measured by reference to mid meridian because?
The chart is a conic projection
What happens to minutes of longitude as you move north or south?
Becomes less than 1nm
In degrees and hours, how much does the sun move in 24 hours?
360 degrees in 24 hours
Which direction does earth rotate?
West to east
How do we get the difference between prime meridian and any given meridian?
Divide degrees by 15.
e.g. 148 degrees E, divide by 15 = 9.86 hours (9 hours 52 mins)
When does astronomical twilight occur?
18 degrees below observers horizon
When does civil twilight occur?
When sun is within 6 degrees of observers horizon
When does BOD occur?
At commencement of morning civil twilight (6 degrees below observers horizon)
When does EOD occur?
End of evening civil twilight
When is the duration of twilight longer?
When you are further south
At the equator, would twilight be short or long?
Short
Where does the sun rise during summer in souther hemisphere?
South of east
Where does the sun rise during winter in southern hemisphere?
North of east
Which direction does sun rise/set?
Rise in the east, sets in the west
What is the formula for daylight available?
EOD - BOD
What is the Flight Planned Track (FPT)?
Line drawn across map joining two points
During winter in the southern hemisphere the LMT of EOD would occur earlier at the destination than the departure point for a flight which travels which direction?
South
The duration of daylight experienced by the occupants of an aircraft is less than the experienced at the departure point or destination for a flight which travels what direction?
East
For a flight which travels south in the southern hemisphere on the autumn equinox, the LMT of EOD would occur when at the destination and departure point?
At the same time at the destination as at the departure.
Places on the same meridian will always have the same LMT for BOD on any given day, true or false?
False
On a place on the same meridian, when will it always have the same LMT for BOD on any given day?
Spring and autumn equinox
Name one chart that is a Mercator Projection?
VTC
With regards to TAS, IAS and GS, what is true with an aircraft flying at 5000 feet in a tailwind?
TAS greater than IAS and less than GS
What is true with regards to great circles on Lamberts Conformal Conic Projection?
Great circles appear as straight lines
What angle does rhumb line cut every meridian on earth surface?
Same angle
Town A is S20 00.0 E119 00.0 and town B is S20 00.0 E129 00.0. The distance between the towns would be what?
Less than 500 nm.
Two towns are on same paralel of latitude, but 10 degrees longitude apart. In this case one min of longitude isn’t a nm because meridians converge towards pole. As you move north or south of equator, a min of longitude becomes increasingly less than a nm
A line that joins places where the magnetic variation is zero is called?
Agonic line
The vertical extent of transition layer will be greater than 1000ft when?
QNH is greater than 1013
On a Mercator chart (VTC) what would a straight line represent?
Rhumb line
On the mercator chart (VTC) what angle does the rhumb line cut each meridian?
Same angle
On the mercator chart (VTC) which direction do great circles appear?
Convex to the pole
What are some conic charts?
WAC and ERC
On conic charts, what do great circles appear as?
Straight lines
On conic charts, what do rhumb lines appear as?
Curves concave to the pole
Which direction can conic charts be joined?
East to west because they have the same standard parallels and projection on same cone
What does one nm equal?
One minute of LATITUDE
