I have just finished my CPL, and this is what you have to do for the skills test (nav section).
You have to plan a dead reckoning leg of 30nm or more to a small town or disused airfield. Something that will be difficult to find. You then have to fly the route using VFR nav techniques. If you get off-track, you must regain track using an approved method.
When you get to the turning point you have to do a nav diversion which is another 30nm away. This has to be planned in the air and an account has to be made for the wind etc. When established on track, you become IMC and have to fix you position from either VOR\DME, or VHF pos fixing. You can also use RAW data GPS but if you can plot lat and long whilst flying you are a better pilot than what I am!!!!! After about 10 mins IF you have to visually fix your pos after the screens come down. Thats about it!!!
Good idea to get some practice in before you start CPL. Hope that helps. If you need anymore info, give me a shout.
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