Air Navigation Revision Notes
LO1: Be able to carry out calculations to determine aircraft distance, speed and time travelled
1 degree of Latitude is equal to 60 nautical miles
1 minute of Latitude is equal to 1 nautical mile
Latitude is measured in degrees and minutes to the North and South of the Equator
The distance between two points on a navigation chart can be measured with dividers using the minute scale along a meridian, close to the area of interest on the chart
Direction of Earth Rotation - West to East
Aviation Speed is measured in knots (nautical miles/hour)
Air Speed Indicator calculates speed by measuring the pressure difference between the pitot and static pressure
Calibrated or Rectified Air Speed equals Indicated Air Speed after correction for Pressure and Instrument Error
Rectified Air Speed after correction for Altitude and Temperature becomes True Air Speed (TAS)
Universal Time is also known as Greenwich Mean Time and is the standard time used in military and commercial aviation
LO2: Understand principles of vectors and triangle of velocities to establish aircraft’s track and ground speed
A vector is a straight line representing speed and direction. The length of the line is proportional to speed and the direction determined by the angle between the line and a datum line
When one vector is added another vector the addition is known as the resultant
A Velocity consists of Speed and direction together
The Air Triangle
Heading Vector
(Heading & True Air Speed) Wind Vector (Wind Speed & Direction)
Drift Angle
Track Vector (Track & Ground Speed)
You need 4 out of 6 components to calculate the remaining 2
Drift is the angle between the Heading and Track Vectors
LO3: Understand principles of the 1-in-60 rule relating to air navigation
Pinpoint
Track Made Good Revised Track
Error in nm
Track Error
Track Required Closing Angle
Line from pinpoint fix to destination is called the revised track
Line drawn on a map between departure and destination is called the track required
LO4: Understand types and limitations of compass systems used for air navigation
Advantages of a Direct Indicating Compass (DIC)
reliable and needs no power supply
most accurate in unaccelerated flight
only reads a magnetic heading
Compass Tilt at North and South Pole is called the dip variation and its values are greatest in the polar regions
Advantages of a Gyroscope
extremely accurate over a short time
takes over from the flux valve whenever the aircraft turns
overtime becomes inaccurate due to gyro wander
A suspended magnet is not part of a gyro-magnetic system
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One advantage of a gyro-magnetic compass, over a Direct Indicating Compass is that it can feed compass repeaters around the aircraft
The principle way in which Inertial Navigation Systems work are they are set accurately on the ground then use the aircraft accelerations in the fore, aft and lateral planes to calculate position
Inertial Navigation Sensors are called accelerometers
LO5: Know the hazards that weather presents to aviation
Flying Weather for Learner Pilots or Beginners are Visual Met Conditions (Visibility and cloud conditions to meet ground controllers requirements)
To fly in instrument metrological conditions you need the correct Instruments and a suitable Pilot Instrument Rating
The effect of a head wind on a calculated ETA could mean an aircraft being late on ETA
To counter the effects of a cross wind and maintain a planned track you turn off into wind by an amount equal to the drift
Estimated Time of Arrival (ETA) is important for air traffic control purposes and for fuel calculations to ensures the aircraft has sufficient fuel to reach the destination
Overdue Action is instigated immediately an aircraft does not arriving at its destination at the estimated time.
To maintain time in a headwind the airspeed must be increased by an amount equal to the headwind component
Aircraft take off into the wind because it enables them to take off at a lower speed.
Wind blowing down runway - zero crosswind component
Wind across runway - zero runway component
Precipitation is a collective noun for rain, snow and sleet
Precipitation at freezing temperatures results in icing
Fog will appear thicker because of the shallow angle on the glide slope
Slant Visibility is known as Runway Visual Range
IceEffects of icing is to decrease lift and increase weight, loss of aerodynamics
and reduced engine performance
Ice on route - plan a new near route or cancel flight
Icing is caused by precipitation in freezing temperatures
Heavy Rain causes restricted visibility and flooded runway
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