NAV Exam Revision Flashcards
What is the term used to describe the technical shape of the earth?
The earth is an oblate spheroid
Name the 4 cardinal compass points and the bearing that each represents
North - 360/000
East - 090
South - 180
West - 270
Define: Great circle
A circle on the surface of the earth whose center and radius are those of the earth
The shortest distance between any 2 points on the globe is a great circle
Define: Small circle
A circle on the surface of the earth whose center and radius are not those of the earth
Define: Rhumb line
A regularly curved line on the surface of the earth cutting all meridians at the same angle
What is a parallel of latitude?
Circles on the surface of the earth whose planes are parallel to the equator. They are all small circles except for the equator and the equator is the zero datum for all latitude measurements
What is a meridian of longitude?
Lines on the earth’s surface join the north and south pole. The zero datum for longitude measurements is Greenwich, London
Is the equator a meridian?
No, the equator is a parallel of latitude and is the only great circle parallel
List 3 ways a pilot can report their position?
Lat and Long Geographical points Line features Bearing and distance Reporting abeam Estimates at future points
What is the distance in NM for arc angles?:
1 minute of arc?
1 degree of arc?
1' = 1 NM 1° = 60 NM
What are the properties of a magnet and a magnetic compass?
Opposite poles attract and like poles repel
Magnets attract or repel other magnets or metals that can be magnetised
If freely suspended then a magnet will align itself with the earth’s magnetic field
Define: Nautical mile (verbatim)
The length of the arc of a great circle which subtends an angle of one minute at the centre of the earth
Define: Magnetic heading
True heading with magnetic variation applied
Which map scales provide greater detail?
The smaller the ratio of the map the greater the detail
List the ways relief can be shown on a topographical map?
Contours Spot elevations Layer tinting Hachuring Hill shading
Name 3 types of basic map projections
Cylindrical
Conical
Plane
What are the 2 most commonly used projections for maps and charts?
Mercator
Lambert
Define: True heading
A heading in relation to true north
Define: Compass heading
Magnetic heading with correction to compass error
What is drift?
The angular difference between the heading of an aircraft and its track
What is UTC?
UTC is Coordinated Universal Time which is based on the atomic clock where each second is corrected for errors
How many minutes of time are there in?:
1° of arc
15° of arc
180° of arc
1° = 4 minutes 15° = 60 minutes 180° = 12 hours
How do you convert degrees into hours and minutes of time?
Degrees x 4 = minutes of time
Conversion of local time to UTC time
For NZ local time:
UTC + 12 or 13 hours depending on time of year to account for daylight savings time
Define: Civil twilight
When the sun’s centre reaches a point 6° below the horizon
What are the properties of a wave?
Amplitude - Height of the wave
Frequency - The number of cycles a wave completes in 1 second
Wavelength - Distance between complete cycles of a wave
What is modulation?
The process of adding audio frequencies to a radio frequency carrier wave enables it to carry information
What is a carrier wave?
A continuous wave being produced at a constant amplitude
What are the 2 main types of modulation?
Amplitude Modulation (AM) Frequency Modulation (FM)
What are the properties of HF, VHF and UHF?
HF = 3-30MHz, used for point-to-point communication VHF = 30-300MHz, experience very little refraction by any ionised layers and thus require a direct line of sight UHF = 300-3000MHz
What is the atmospheric layer that affects radio propagation?
The Ionosphere
What is the minimum equipment needed on board an aircraft for VDF to work?
Two way radio communication equipment operating on the correct frequency
Define: Ground wave
A wave that follows the earth’s surface contour
Define: Space wave
High-frequency waves that 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 ground waves become too weak to be received to the point at which the first sky wave has returned to the surface of the earth.
What is an NDB?
Non-directional beacon
LF-MF
Long Range
What is a VOR?
Very High Frequency Omni-directional Range
VHF
360 radials
What is an ADF?
Automatic direction-finding radio receiver
Can be tuned to an NDB to determine the direction of the beacon relative to the aircraft
What is the angular accuracy of NDBs and VORs?
NDB = ±10° VOR = ±5°
What is the cone of ambiguity?
NDBs and VORs cannot transmit vertically therefore there is a cone above the beacons at ~45° from the vertical where no signal will be detected from the beacons
What is a DME?
A short-range navigational aid, normally paired with a VOR that provides distance and ground speed information with a range of 200NM
Describe slant range?
The distance measured to an aircraft describing both the horizontal and vertical components
What are the components of an ILS?
Localiser
Glide path
Markers
What is the recommended glide path for an ILS?
3°
What is the decision height and RVR for the ILS categories?
CAT I ILS = 200ft, 800m CAT II ILS = 100ft, 400m CAT IIIA ILS = 0ft, 200m CATIIIB ILS = 0ft, 50m CAT IIIC ILS = 0ft, 0m
How does INS work?
Measures an aircraft’s location using accelerometers and gyroscopes
Detects motion and can pinpoint where an aircraft has travelled based on its known starting point
How many different satellites are required for GPS?
4 (3)
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 an SSR system
Interrogator
Transponder
This frequency is used for?:
UHF
RADAR DME ILS GPS Military communications
This frequency is used for?:
VHF
VOR
Civil communications
This frequency is used for?:
HF
Long range communications
This frequency is used for?:
MF-LF
NDB
What is the track error formula for the 1 in 60 rule?
TE = (Distance off track x 60)/Distance flown
What is the correction angle formula for the 1 in 60 rule?
CA = (Distance off track x 60)/Distance to go
