Enroute Charts and Symbols

What Are Enroute Charts?

Enroute charts provide a graphical representation of the airspace structure, including airways, waypoints, navigation aids, and airspace boundaries. They are used for both IFR and VFR navigation, with symbols standardized according to ICAO Annex 4 for global consistency.

Key Enroute Chart Symbols

• Airways and Routes: Solid or dashed lines indicate controlled (Class A) or uncontrolled routes. Advisory airspace and FIR boundaries are also clearly marked.
• Navigation Aids: Symbols represent VORs, DMEs, NDBs, and composite aids like VORTAC or TACAN. Each has a unique symbol, so accurate identification is crucial.
• Reporting Points: Compulsory and non-compulsory reporting points are marked with different shapes, while waypoints (typically for RNAV) have their own symbol.
• Obstacles and Visual Aids: Obstacles are shown with symbols indicating whether they are lit or unlit, single or multiple, and exceptionally high. Aeronautical ground lights and lightships are also depicted.

Measuring Tracks and Distances

Enroute charts use a specific scale, often indicated in the chart legend. Pilots use the scale to measure distances between points and plot tracks using a protractor or navigation ruler. Calculations must account for the chart's conformality—straight lines approximate great circles, ensuring accurate navigation over long distances.

Chart Legends and Scale

The chart legend explains all symbols and the method of representing scale. Understanding the legend is vital for interpreting less familiar symbols and performing accurate scale calculations.

Position Fixing

By referencing VOR radials and DME distances, pilots can fix their position on the chart. This skill is tested in both practical navigation and theoretical exams, requiring a clear understanding of how symbols relate to real-world navigation aids and reporting points.