Fundamentals of Air Navigation Flashcards
Earths shape
Oblate spheroid
Direction of earth rotation
Anticlockwise
The axis of earth rotation
Polar axis (axis going through geographic poles)
Geographic poles
True north and south poles which don’t move
Magnetic poles
Points where the earth’s magnetic field enter and exit, they are moving points, currently lying in northern Canada and near the coast of Antarctica
Equator
Imaginary line on the earth’s surface, with equal distance to the N and S pole, it is a great circle
Great circle
Intersection of a sphere and a plane that passes through the centre point of a sphere, dividing the sphere into 2 equal halfs
Parallels of lattitude
Imaginary lines around the earth that are parallel to the equatot that connect points of equal lattitude (measured in degrees, minutes and seconds)
1 degree of lattitude = ___nm
60nm
1 minute = ___nm
1nm
Meridians of longitude
Imaginary lines connecting equal points of longitude (measured in degrees, minutes and seconds)
Greenwhich (prime) meridian
The meridian that sits at 0 degrees longitude
Lattitude/longitude
Geographic co-ordinates that enable locations on earth to be specified using in degrees, minutes and seconds
360° method of indicating direction
Compass rose method of indicating and to measure direction from true north
Earths magnetic field
Earth is effectively a large magnet and as such has a magnetic field allinging itself to lines of flux (magnetic field lines), the lines are vertical at the poles and horizontal at the equator
True north
Place on earth where the axis of rotation enters the earth in the northern hemisphere
Magentic north
Place of earth where lines of magentic flux enter the earth in the northern hemisphere
Compass north
The north direction indicated by the compass (its not the same as magentic north due to comapss errors caused by manafacturing, electrical and magnetic interference)
360° =
N
180° =
S
270° =
W
090° =
E
045° =
NE
135° =
SE
315° =
NW
225° =
SW
True direction
The direction between 2 points in relation to true north
Magnetic direction
The direction of 2 points in realtion to magnetic north (or direction in °true corrected for magentic variation)
Compass direction
Track measured on chart corrected for magnetic variation and compass deviation
Magnetic variation
The angular difference between true and magentic north which changes regulary
Magnetic dip
The angle between the earths surface and the earths magnetic field lines (magnetic field lines are not always parallel to the earths surface)
Isogonal
Line on chart that joins areas of equal magnetic variation
Compass deviation
The difference between what the compass indicates compared to actual magnetic direction (deviation card shows deviation corrections)
True bearing
The direction of a track between 2 points as measured on a chart and measures against true north
Magnetic bearing
The direction of a track between 2 points corrected for magnetic variation
Compass bearing
The magnetic bearing corrected for compass deviation
Relative bearing
The bearing of an object referenced from the nose of the aircraft (nose = 360°, tail = 180°)
Statute mile = ___ ft
5280ft
Nautical mile = ___ ft
6080ft
Km = ___ ft
3280ft
m = ___ ft
3.37ft
ft = ___ m
0.305m
1nm = ___ km
1.852km
1sm = ___ km
1.61km
1sm = ___ nm
0.87nm
1km = ___ nm
0.54nm
1km = ___ sm
0.621sm
1nm = ___ sm
1.151sm
kt
knot, the standard unit for aircraft speed it is equal to 1nm/h
GS
Ground speed, the speed of an aircraft relative to the ground, measured in kts
IAS
indicated airspeed, the airspeed displayed on the airspeed indictor, the aerodynamic speed of the aircraft
CAS
calibrated airspeed, the indicated airspeed corrected for instrument and pressure (position error)
TAS
True airspeed, calibrated airspeed corrected for differences in pressure and temperature density. It tells us how quickly we are actually moving through the air
Difference between speed and velocity
Velocity is speed and direction, whilst speed is just how fast something is moving (no direction of movement given)
Ground position
determining where you are on the ground, e.g. next to a major landmark
DR positioning
position calculated by dead reckoning (flying a bearing or direction for a period of time and using ground speed to figure out where the aircraft will be)
Fix
position of aircraft at a given time determined using reference to ground features or navigation aids (e.g. overhead a township)
Position line
A line on which the aircraft is known to be at a specified time. Could be an actual or imaginary line.
Ways to reference position
Using a place name, Using bearing and distance from a place name, using latitude/longitude geographic coordinates, using relative bearing + clock face method
Height
Vertical distance above a specified datum
Altitude
Vertical distance above mean sea level
MSL
Mean sea level, used to measure altitude
Ground level
Datum for height (varies depending on height of ground)
AGL
Above ground level
Elevation
Used to describe the distance of an object above MSL
PA
Pressure altitude, the altitude in the ISA with the sane pressure as the current prevailing pressure
QNH
Sea level pressure
Effects of a change in MSL pressure on altimeter reading
High to low look out below. if travelling from high to low pressure the altimeter will read higher
Effects of a change in temp on altimeter reading
If temp is warmer then ISA then altimeter under reads meaning you are actually higher then indicated
Altimeter setting above FL150
1013.2
Altimeter setting at or below 13,000ft
Area or aerodrome QNH
Altimeter setting between 13,000ft and FL150
Area QNH advised by ATC
Altimeter setting when ascending above FL150
1013.2
Altimeter setting when descending through FL150
Set appropriate area/aerodrome QNH
True track required
The path we plan to fly between 2 points measured off a chart
Magnetic track required
True track with magnetic variation applied
W/V
Wind velocity, the speed and direction the wind is blowing from, it is written as a 5 figure digit group, the first 3 digits are true/magnetic direction and the last 2 digits are speed
Headwind
Wind on the nose, decreases GS
Tailwind
Wind on the tail, increases GS
Crosswind
Wind coming from either left or right of aircraft pushing it off the track required
True heading (TH)
Heading in relation to geographic poles, the track is corrected for W/V and the resulting drift. We can resolve the triangle of velocities to find it using our navigation computers
Magnetic heading
true heading corrected for magnetic variation
Compass heading
magnetic heading corrected for compass deviation
Drift
The correction we apply to our track to allow for any crosswind, drift is the angular difference between our heading and our track.
Port drift
pushes the aircraft left
Starboard drift
pushes the aircraft right
planned drift
calculated using navigation computer
Actual drift
Is drift we actually experience
TMG
Track make good, the track the aircraft travels across the surface of the earth (expressed in degrees true or degrees magnetic, in flight adjustments can be made)
Port
Left-hand side of the ship
Starboard
Right-hand side of the ship
Wind correction
The amount of degrees that the aircrafts nose is pointed into the wind. It is the same but opposite to drift
Wind correction angle
The angle you must allow for drift so that you will maintain your planned flight
Deduced (dead) reckoning
Having flown a leg we are able to ascertain GS (e.g. if it takes 15mins to cover 30nm then using a nav computer we can work out that GS is 120kt, this allows us to calculate how long it will take to get us to the next checkpoint
TE
track error, the angle between the required track and the track made good
CA
Closing angle, the additional angle or correction which must be made above the TE to regain track (is only TE is applied we will parallel track)
ETD
estimated time of departure, the time that we estimate we will be departing
ATD
Actual time of departure
EET
Estimated elapsed time, the estimated time flown on each leg
ATA
The actual time of arrival
Date/time group
Six figure system - dd/hh/mm
UTC
Coordinated universal time (standard time used in aviation)
NZST
NZST is 12 hours ahead of UTC
NZDT
NZDT is 13 hours ahead of UTC
Conversion between ETD/ETA and UTC
Subtract 12 hours if NZST and subtract 13 hours if NZDT. NZDT starts on the Sunday of September and ends the first Sunday of April.
Sunrise
The exact time when the upper limb (top) of the sun is first visible on the horizon
Sunset
The exact time when the upper limb of the sun is no longer visible on the horizon (gone below the horizon)
Daylight
Period between MCT and ECT
Twilight
Periods where there is light before sunrise and light after sunset
MCT
Morning civil twilight, starts when the center of the sun is 6° below the horizon before sunrise and ends at sunrise
ECT
Evening civil twilight, starts and sunset and ends when the center of the sun is 6° below the horizon after sunset
What factors effect times of sunrise and sunset (duration of daylight)
- seasons: during summer sunset is later and sunrise is earlier, there is minimal change in times at equator and a large change at poles
- latitude: because earths axis of rotation is inclined different locations along the meridian receive different amounts of sunlight
Factors that effect duration of twilight
Twilight is longer in the south than in the north (because sun rises at a more oblique angle to the earth then the tropics, meaning it traverses through the 6° slower)
Factors that affect daylight conditions
- Altitude: the higher up you are, the shorter the nights and the longer the days
- Atmospheric conditions: cloud/smog make it appear darker
- Obstructions: mountains limit daylight
How do you find out MCT or ECT
Look at AIP Gen 2.7-1 map and table to find out what zone and the MCT/ECT associated with the zone, estimate well if the date is in-between table dates. Convert to appropriate time as the table in UTC
Chart scale
The ratio of a given chart length to the actual distance on earth that it represents.
Scale
Chart length/earth distance
