Let the Devil Wear Black - Memoirs of an analyst

James F. Linden - Writer ...
This site:
Let the Devil
Wear Black:
James Linden:


Resources - VOR Compass Roses

Navigation before GPS.

Chapter 22

It has happened to us all — you are just travelling along when you notice something out of the window and want to know what it is.

That Y–shaped stretch of water and those hills in the far–off distance. What are they and where are they. For that matter, where are we?

FS98 presents a wonderful opportunity to take off from whichever aerodrome you happen to be at and fly around, without a care, just messing around, doing acrobatics or whatever you like — after all, you have the six standard instruments in front of you so you know where the aeroplane is and what it is doing relative to the local environment.

You know: how fast you are going forwards; the aeroplane's attitude relative to the local environment; how far off the ground or above mean sea level you are, depending upon whether it is set to one or the other; to what extent the aeroplane is slipping sideways; the direction it is pointing as though viewed from above; and, how fast it is gaining or losing altitude.

The one thing that these instruments do not tell you is where you are.

On a VFR map — this is one of mine from 2001, ‘Sheet 5, Central England and Wales Edition 4, 1:250,000’ and has roughly the same polar drift as in FS98 — you will notice that there are a number of these VOR compass roses scattered around the countryside — they are oriented with magnetic north.

In the centre of each is a small hexagon and from that leads a short line and then a box. In that box there is a three letter code and a number. The three letter code — in this case ‘STU’ for ‘Strumble Head’ — identifies the beacon and the number is the frequency that it operates on.

In this case, the hexagon has a box around it and the identification includes ‘DME’ — Distance Measuring Equipment — which is co–located with the VOR transmitter.

This is how you can use them in FS98.

On the control panel, just to the right of the six main instruments, are two VOR instruments that look like this.

Each has a knob at the bottom–left and on FS98, if you position the mouse over them, you will get a mouse pointer that says ‘+’ when the mouse is on one side and a ‘–’ on the other. Clicking these will rotate the outer ring with the compass positions on it.

If you click on the large white rocker switch at the bottom of the panel, around a third of the way along from the left, this instrument panel appears.

On it, you can set the VOR tuners to the frequencies denoted on the VOR rose compasses on your VFR map.

Select two base stations that will allow you to fly along the beam from one whilst using the other to tell you how far along that path you have gone from its angle.

Here, we are flying from the Birmingham area, up to Manchester so we have set VOR2 to 113.55 which is the VOR we want to fly along the line of — MCT — and we have set up VOR1 to 115.70 which is Tissington — TNT.

We can draw a line on the map — in Chinagraph pencil or dry–wipe marker — from the VOR down to where we are.

If we twiddle the knob on VOR1 now, we can get the pointer to move like so. Where the marker is central, the bearing is read off the dial.

We can now put that on the TNT VOR on the map and draw a bearing off that.

Where they intersect, that is where we are — to the accuracy of the system, that is but then we are travelling at round two miles per minute.

This is where they cross and we can see that the Y–shaped water body in front is Blithfield Reservoir...

...and that the hills in the distance are the bottom–end of the Pennines, close to Alton Towers.

Use of photographs of 2001 VFR map for illustrative/education purposes only, coming under fair use. Note that you should only use up-to-date VFR maps when flying and these are published by the Civil Aviation Authority. but they are sold in a number of places. One place you can buy them online is AFE.

“Well, they are working for Gazelles. Now, as long as they work for Gazelles, they're not working for anybody else and that can only be for the benefit of everybody else.”

Copyright © 2012-2014 James F Linden. All Rights Reserved.