Flight Navigation General

Question 1

What is an isogonal?

Answer 1

A line joining points of equal magnetic variation.

Question 2

When flying from Auckland to Perth on a great circle, will the track be a curve or straight line if you were using a Lamberts chart?

Answer 2

Great circles are straight lines on Lamberts charts.

Question 3

Explain a mercator projection

Answer 3

• Turns a sphere into a cylinder
• All meridians are straight lines with parallel spacing
• Rhumb line will appear straight
• Great circle appears curved.

Question 4

Explain a Small Circle

Answer 4

Any circle drawn on the earth whose radius is not the earth.

Question 5

How do you calculate TAS given IAS?

Answer 5

TAS = IAS + (miles a minute x alt in thousands )

Question 6

How do you calculate bank angle for a rate 1 turn given airspeed?

Answer 6

Bank angle = (TAS/10) x 1.5 or + 7.

Question 7

Formula for turn radius / arc turn on?

Answer 7

Turn radius = 1% of TAS / 2.

Question 8

What is earth convergency?

Answer 8

The angle of inclination between two meridians at a given latitude.

Question 9

What is the speed of rotation of the Earth?

Answer 9

900kts at the equator

Speed = 900 x cos(latitude)

Question 10

How do you calculate a reciprocal heading

Answer 10

Initial heading ± 200 ±20.

Question 11

What is a Great Circle

Answer 11

A circle drawn on the surface of the earth whose radius is the earth. The shortest distance between two places.

Question 12

When flying from Auckland to Perth on a great circle track, what happens to heading?

Answer 12

It slowly increases as great circles are concave to the equator on Mercator charts.

Question 13

Explain lambert projection

Answer 13

• turns a sphere into a cone
• meridians are straight lines
• lats and longs intersect at right angles
• rhumb lines are curved concave to poles
• great circles are straight.

Question 14

Explain a Rhumb Line

Answer 14

A line drawn on the earth’s surface which cuts each meridian at the same angle.

Question 15

What is the conversion angle?

Answer 15

Angular difference between the great circle track and rhumb line track between two points.

Question 16

How do you calculate a ToD?

Answer 16

3 x altitude to lose in 1000’s of feet plus 1nm per 10kts of slowdown required.

(This gives 333 feet per nm, can divide height to lose by 3 and add a zero for 300 feet per nm version).

Use top version for ToD but brackets version for non-precision or visual approaches.

Question 17

Formula for distance on a DME arc?

Answer 17

Distance=radials / (60/DME distance).

Question 18

Explain parallels of latitude

Answer 18

Small circles (except equator) that are Rhumb lines crossing meridians east to west.

Question 19

Explain orthomorphism.

Answer 19

• The scale on the chart must be correct to the scale nearby.
• Parallels and meridians must cross at right angles.

Question 20

What is the departure formula?

Answer 20

For figuring out how many nm east-west at a particular latitude.

Distance = longitude (in arc minutes) x cos(latitude)

Question 21

Define a nautical mile.

Answer 21

• The distance on the surface of the earth which subtends an angle of 1 arc minute.
• 6080 feet.
• 1° latitude = 60nm.

Question 22

What are the three kinds of errors an INS can have?

Answer 22

1. Bounded errors - errors that do not increase with time or increase/decrease in a cycle. E.g. north alignment error will produce bounded velocity error.s
2. Unbounded errors - errors that increase with time. E.g. initial position errors and north alignment errors (in position).
3. Inherent system errors. E.g. change in distance travelled with height, the fact earth is not a true sphere.