Topographical Chart — Page 132, Lesson 134

Let’s start with the topographical chart itself. This is the kind of chart you’ll use for visual navigation and flight planning under Visual Flight Rules or even as a backup reference during instrument flight. It shows both aeronautical information and topographical information on the same sheet. I’ll begin with the aeronautical information block. Airports on this chart are depicted with their ICAO four-letter code — for example, LAHR is EDTL and Stuttgart is EDDS. Alongside that code you get the location name, the elevation in feet, the length of the longest runway available in metres, and the tower communication frequency. If you see a small (v) next to the airport data, that tells you VHF Direction Finding — abbreviated VDF — is available at that aerodrome. VDF is a service where the ground station can give you a magnetic bearing from the station to your aircraft, based on your VHF transmission. Next, waypoint information. Compulsory and non-compulsory reporting points are shown on the chart with their assigned name. A compulsory reporting point is one where air traffic control requires you to report your position; a non-compulsory one is for your own situational awareness or for when ATC specifically requests it. Navaid information gives you each navigational aid’s frequency and its identification code. The coordinates of those navaids are tabulated at the side of the chart, so you can plot them precisely on your map. Then we have types of airspace. When you plan a flight, you must consider the various types of airspace and their restrictions. The chart depicts restricted, danger, and prohibited areas with specific symbols — you’ll see those in the chart legend. Let me define each one precisely, because these are legally binding. A restricted area is airspace of defined dimensions within which the flight of aircraft is restricted in accordance with certain specified conditions. That means you can fly through it only if you meet those conditions — often requiring prior permission or an active clearance. A danger area is airspace which has been notified as such within which activities dangerous to the flight of aircraft may take place or exist at such times as may be notified. This does not automatically prohibit you from entering, but you do so at your own risk, and you should check the times of activity. A prohibited area is airspace of defined dimensions within which the flight of aircraft is prohibited. That means no entry under any circumstances unless you have specific exemption from the state authority. Now let’s move to the topographical information side of the chart. You’ll see symbols for natural high points, with their elevation given in feet. The chart also uses terrain contour tints — those are colour bands that represent different elevation ranges. Those tints are labelled in both feet and metres. At the bottom right of the chart there is a feet-to-metre conversion scale, so you can convert between the two units easily. The conversion factor given here is 1 metre equals 3.28 feet. Now, one of the most important safety features on this chart is the Minimum Grid Area Altitude, abbreviated GRID MORA. These figures are shown inside each half degree of latitude and longitude. The value you see is a two-digit number, and you must add two noughts to it. For example, if you see 47, that means 4700 feet. That resulting value provides a clearance of all terrain by 1000 feet in areas where the highest point is 5000 feet or lower, and 2000 feet where the highest point is 5001 feet or more. So the GRID MORA guarantees that if you fly at or above that altitude within that grid square, you will clear every obstacle and terrain feature by at least that margin. Finally, the excerpt includes an example question: “What are the magnetic track and distance, in nautical miles and kilometres, between aerodromes LAHR (EDTL) and STUTTGART (EDDS)?” The answers are on page 141. That’s the kind of practical task you’ll be doing with this chart — measuring tracks and distances between two points using the chart’s scale and magnetic variation information.