Re: What GPS do you use?
I have a Magellan Meridian and I have noticed that it will track a straight line on a map. That is, the track to somewhere will follow the same track that you draw on a chart with a pencil.
The Garmin GPS III will give a great circle track. Example: from central Calif. to Alabama will take you up over kansas or Nebraska somewhere before it "curves" down. The Meridian doesn't do that.
Now, if you are flying to a place that you can see from 30 miles away you will find the Meriidian will be pointing you to one side or the other of the landmark you can see. Then it will start to curve in about 1/2 way there and finally cross right over your destination.
I think what is going on is your visual sight line is small part of a great circle but because the Meridian is set up to match the normal projections on a map it actually takes you in a curve that is a slightly longer route. I'm always thinking, "Why do I want to go over there, I can see where I'm going and it is this way." At twenty miles it is very noticeable; like several degrees.
Strange the things we take for granted that aren't really the way we think they are.
I normally draw a line on the chart and do pilotage, using the GPS to confirm my pilotage and correct for my compass.
Darryl
I have a Magellan Meridian and I have noticed that it will track a straight line on a map. That is, the track to somewhere will follow the same track that you draw on a chart with a pencil.
The Garmin GPS III will give a great circle track. Example: from central Calif. to Alabama will take you up over kansas or Nebraska somewhere before it "curves" down. The Meridian doesn't do that.
Now, if you are flying to a place that you can see from 30 miles away you will find the Meriidian will be pointing you to one side or the other of the landmark you can see. Then it will start to curve in about 1/2 way there and finally cross right over your destination.
I think what is going on is your visual sight line is small part of a great circle but because the Meridian is set up to match the normal projections on a map it actually takes you in a curve that is a slightly longer route. I'm always thinking, "Why do I want to go over there, I can see where I'm going and it is this way." At twenty miles it is very noticeable; like several degrees.
Strange the things we take for granted that aren't really the way we think they are.
I normally draw a line on the chart and do pilotage, using the GPS to confirm my pilotage and correct for my compass.
Darryl
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