NAV Flashcards
What is the term to describe the technical shape of the earth?
Oblate Spheroid
Name the four compass points and the degree that each represents.
North - 0° or 360°
East - 90°
South - 180°
West - 270°
Define: Great Circle
A circle on the surface of the Earth whose centre and radius are those of the Earth itself.
Define: Small Circle
A circle on the surface of a sphere whose centre and radius are not those of the sphere.
Define: Rhumb Line
A regularly curved line on the surface of the Earth cutting all meridians at the same angle.
What are Meridians of Longitude and Parallels of Latitude?
Meridians of Longitude - Lines joining the poles that follow the great circles.
Parallels of Latitude - Small circles on the Earth’s surface, except for the equator.
List three ways a pilot can report their position and how they do this?
Latitude and Longitude Geographical Line Features Bearing and Distance Reporting Abeam Estimates at future positions
Calculate the distance in nautical miles for the following arc angles.
1 min of Arc = 1NM
1 degree of Arc - 60NM
What are the properties of a magnet?
A magnet attracts or repels other magnets or other metals that can be magnetised.
When freely suspended, a magnet aligns itself with the Earth’s magnetic North and South poles and the same end always aligns with the same Earth’s pole.
Define: Nautical Mile
The length of the arc of a great circle which subtends an angle of one minute at the centre of the Earth.
What is the ICAO standard for a Nautical Mile?
6,076.1ft OR 1,852m.
Map Scales - which shows greater detail?
1:500,000 shows greater detail than 1:1,000,000 (the smaller the bottom number, the greater the detail).
How can relief be shown on a topographical map?
Contours Spot Elevations Layer Tinting Hachuring Hill Shading
List the three types of map projection
Cylindrical Projection
Conformal Conical Projections
Azimuthal Or Plane Projections
List the two types of map projection that are most commonly used and their cartographers.
Mercator Cylindrical Projection
Lambert’s Conformal Conical Projections
Define: True Heading
Heading in relation to True North.
Define: Compass Heading
Magnetic heading with correction for compass error.
Define: Magnetic Heading
True heading with magnetic variation applied.
What is Drift?
The angular difference between the heading of an aircraft and its track.
What is UTC?
Coordinated Universal Time (Greenwich Mean Time) which is based on the atomic clock where each second is corrected for errors.
How many Minutes is 15° of Arc?
15° = 60 minutes
How many Minutes is 1° of Arc?
1° = 4 minutes
Define: Civil Twilight
When the Sun’s centre reaches a point 6° below the horizon.
What are the properties of a wave?
Amplitude - How tall the waves are
Wavelength - The distance between individual waves.
Frequency - The number of times a wave repeats itself every second.
Define: Modulation
The process of adding audio frequencies (i.e. sounds we can hear) to a radio frequency carrier wave enables it to carry information.
What is a carrier?
A continuous wave being produced at a constant amplitude.
What are the two types of modulation?
Amplitude Modulation (AM) Frequency Modulation (FM)
What is the atmospheric layer that affects radio propagation?
Ionosphere
What is the minimum radio equipment required on an aircraft for VDF to work?
Appropriate two-way radio communication equipment operating on the correct frequency.
This frequency is used for: UHF
RADAR DME ILS GP GPS Military Communications
This frequency is used for: VHF
VOR
ILS
LLZ
Civil Communications
This frequency is used for: HF
Long Range Communication
This frequency is used for: LF-MF
NDB (Non Directional Beacon)
Define: Ground Wave
A wave that follows the Earth’s surface contour.
Define: Space Wave
High Frequency waves which do not get refracted by the atmosphere and travel into space.
Define: Skip Zone
The area in which no signals are received, extending from the point at which the ground wave becomes too weak to be received to the point on the surface of the Earth where the first returned sky wave is received.
What is an NDB and what are its properties?
Non Directional Beacon
LF
MF
Long Range
What is a VOR and what are its properties?
Very High Frequency Omni-Directional Range
VHF
360 radials
What is an ADF?
Automatic Direction Finding
Radio receiver that can be tuned to NDB’s and determine the direction of the beacon relative to the aircraft.
What is the Accuracy of a NDB?
+/- 10°
What is the Accuracy of a VOR?
+/- 5°
What is the cone of ambiguity?
NDB’s and VOR’s can not transmit vertically, therefore there is a cone approximately 45° either side of the vertical.
What is a DME?
A short range navigation aid, normally paired with a VOR that provides distance and ground speed information out to a range of 200 NM.
Describe Slant Range.
The distance measured has a vertical as well as horizontal component, and is called a slant range.
What are the parts of ILS?
Localiser
Glide Path
Markers
What is the glide path angle for ILS?
3°
What are the decision heights and RVR for CAT I ILS?
DH - Not lower than 200ft
RVR - Not lower than 800m
What are the decision heights and RVR for CAT II ILS?
DH - Not lower than 100ft
RVR - Not lower than 400m
How does INS work?
Measures aircrafts location using accelerometers and gyroscopes. Detects motion and can pinpoint where an aircraft has travelled based on its known start point.
How many satellites are required for GPS use in air navigation?
3-4
What is differential GPS?
By using a fixed ground receiver as a reference point, an aircraft’s position can be very accurately calculated by error checking its location with the fixed point.
Name the components of the SSR system.
Interrogator
Transponder
What are the properties of the wavelength: MF Band?
Sky waves associated with refraction occur significantly only by night.
What are the properties of the wavelength: HF Band?
When the HF band is used for point to point communications, different frequencies are required by day and night in order to maintain contact over any given range.
What are the properties of the wavelength: VHF and higher bands?
Waves in these frequency bands experience little refraction by any of the ionised layers, passing through to become space waves.
What is the Track Error formula for the 1:60 rule?
TE = Distance Off Track/Distance Along Track × 60
What is the Closing Angle Formula for the 1:60 rule?
CA = Distance Off Track/Distance to GO × 60
