PPL Skills - Navigation

Introduction

Defining Some Terms

• True North
• With reference to the geographical north pole. Most maps and charts are aligned to true north
• Magnetic North
• Compasses all point towards the magnetic north pole, which is somewhere over Canada
• For this reason, compasses are a lot less reliable in higher lattitudes closer to the magnetic north pole.
• VOR radials and runways are all referenced to magnetic north and not true north
• Magnetic Variation
• Refers to the deviation between Magnetic North and True North, and differs from location to location
• An Isogonic Chart shows the magnetic variation in different regions. Each isogonic line represents a certain magnetic deviation which all regions along that line have. The concept is similar to contour lines on topographic maps
• Magnetic variation is not uniformly spread because the earth is also not uniformly magnetised
• When flying across long distances, it is important to take changing magnetic variation into account.
• Magnetic Deviation
• Refers to the internal inaccuracies within an aircraft's compass. 
• Due to things like magnetic fields arising from electrical systems, a compass may not give an accurate magnetic heading at every heading.
• Course
• Intended path across the ground
• True course
• If measured with reference to true north
• Magnetic Course
• If measured with reference to magnetic north
• Heading
• DIreciton in which the aircraft's nose is pointing
• Similarly, may also be classified as:
• True Heading
• Magnetic Heading
• The heading is only the same as the course if there are no winds
• If there are winds, the pilot must fly a heading different from the course in order to counter the effects of wind
• Track
• Refers to path across the ground that the aircraft actually flies
• Drift Angle
• Angle between the course and the track if no effort is made to correct for wind (ie the heading = course)
• Wind Correction Angle
• The correction that the pilot has to take into account to correct for wind
• Essentially the same as the drift angle

Calculations

• Wind Triangle
• Combining the effect of wind and the aircraft's movement through the air to find out the speed and path over the ground. 
• Essentially vector resolution
• See here
• Can be resolved using an E6B flight calculator, or trigonometry 
• Speeds
• 1knot = 1 nautical mile per hour = 1.15 statute miles per hour
• Fuel consumption
• Piston engine aircraft typically measure fuel in volume (gallons), while higher performance aircraft like jets typically measure fuel in weight (pounds)
• This is because in different conditions, fuel expands and contracts and so volume becomes a less accurate measurement of the actual amount of fuel, particularly at high-altitude and low-pressure environments in which jets operate. 

Navigational Systems

Flight Planning (more for GA VFR)

Gather all necessary information

• VFR Sectional Charts
• Along the whole routes
• Including those along of adjacent sections if the planned route passes near the edge of a section
• Can be obtained online or at flight stores
• Read NOTAMs
• Gather weather information at departure airport, destination, and along the route
• METARs
• Visibility, winds aloft, surface winds, temperature
• POH / AFM
• Check for updates
• Plan weight-and-balance and CG, check within limits
• Check runway length is above minimum given conditions