Expert: David Bidwell - 7/30/2009

Question
Hi David,

I wondered if you could help me. I am training for my PPL in the UK and I am currently at the navigation stage. I have been told by my instructor to plan a route from Leeds (EGNM) to Leeds, via Ripon, Malton and York.

I have drawn the route on my chart but I am not sure about the magnetic variation during the trip.

During my training I have been told to use the whole number that applies between the isogonals. From Leeds to Ripon the magnetic variation is 2 degree West (as it is in between the 1.5 and 2.5 isogonal), but the leg from Ripon to Malton crosses the 2.5 isogonal for about 4nm, so I am a bit confused as to what magnetic variation to use for this leg. As it crosses the 2.5 isogonal, do I calculate the heading from Ripon to Malton based on 3 degree West variation?

The next leg crosses the isogonal again to go back to the 2 degree variation. So do I calculate the heading from Malton to York as 2 degree West variation?

Hope I am making sence?

Thanks in advance.

Paul.

Answer
Hi Paul,
Unfortunately, I do not have access to that chart. From what you are telling me, I personally would not change my course for a half of a degree.  Since you will be using winds aloft in your calculations, remember that they are a forecast. You should be combining pilotage techniques along with dead reckoning. Keep in mind, that it is great to be technical but sometimes you just need to be practical.
Good Luck, Dave