Where are we?

General Navigation Terms

• air position: calculated position assuming no wind effect
• dead reckoning (DR) position: calculated position with due allowance for possible wind effect

• great circle: a circle on the surface of a sphere whose centre coincides with the centre of the sphere; the shortest distance between two points
• rhumb line: cuts all meridians at the same angle

Fun fact: the equator is both a great circle and a rhumb line.

Now, who has actually used an astro compass? Not  me. But they're still out there.

• Greenwich Hour Angle (GHA): the angular distance between the Greenwich meridian and the meridian of a celestial body, measured westward through 360 degrees
• Local Hour Angle (LHA):  the angular distance between an aircraft's meridian and the meridian over which a celestial body is located, measured westward; LHA = GHA + E (or - W) longitude

Since the earth is (approximately) spherical and maps are flat, projections of the earth's surface onto paper have some distortion.

Projections

• Mercator
• straight line represents a rhumb line
• distortion increases with distance from the equator
• Transverse Mercator
• used on VTA charts
• straight line approximates great circle track
• Lambert Conformal Conic
• used on VNC and WAC charts
• straight line approximates great circle track
• Polar Stereographic

You need to know: 

• 1 degree of latitude is 60 NM
• 1 timezone is 15 degrees of longitude

Enroute Charts

• information for radio navigation (no cities / towns / topography)
• scales are not constant - they vary to suit the requirements of each individual chart
• Lambert Conformal Conic projection
• Low Altitude (LO): for use up to, but not including 18 000 ft
• High Altitude (HE): for use at 18 000 ft and above
• Terminal Area: for use up to, 18 000 ft larger scale for congested areas