There are many other symbols used on aeronautical charts and some of these are outlined below. If you’re ever unsure about a symbol on the chart, you will find a description of all the symbols in the chart’s legend.
Different types of aerodromes have slightly different symbols on our charts.
The name of the aerodrome, its ICAO code, and its elevation in feet are written next to the aerodrome symbol.
At larger airfields, Visual Reference Points (VRPs) are often used when communicating with air traffic controllers.
VRPs are marked on the chart with a blue cross inside a circle. The name of the VRP is written alongside in a box.
An Area of Intense Aerial Activity (AIAA) is airspace within which the intensity of civil and/or military flying is exceptionally high or where aircraft (often many together) regularly participate in unusual manoeuvres. You are strongly advised to be in contact with a radar unit when passing through these areas.
AIAAs are outlined on the chart by blue diamonds.
Inside a High Intensity Radio Transmission Area (HIRTA) you may experience interference with your communication and navigation radios.
HIRTAs are marked on the chart by a red circle with cross hatching through the circle.
Gas Venting Sites can cause severe turbulence up to the marked altitude when the ground stations are venting natural gas under high pressure.
Severe turbulence means you should plan to fly around them!