Whirlybird said:
Once the vis is down to 7 or 8km (it doesn't have to be really bad) it's much harder, and you really have to be on the ball to notice if your heading isn't working. That may be because the wind has changed or whatever, not because you're not flying accurately. And then, IMHO, is the time to use VOR and GPS and anything else you've got as a back-up
All very true. It's not impossible to fly visually in very poor viz (even down to 3km or less), but the whiz wheel and traditional ded-reckoning techniques are definitely
not the way to go. In this kind of viz, use line features - the bigger the better. Follow the line features until you reach good position fixes on those line features, e.g. follow a motorway until it reaches the town, then follow the edge of the town to the destination airport.
If you're starting somewhere other than a line feature, then find a line feature to follow, and fly to it - but fly to one side of your first position fix. E.g. fly to the south of your position fix, then turn north to follow your line feature - that way you know that your first position fix will be in the direction you are going.
Definitely
not the kind of navigation for student pilots or low-hours pilots to be attempting un-aided, but certainly not impossible, and (like a lot of difficult things) very rewarding when it goes right! And if the weather is that bad, you'll probably be using up some of your capacity simply keeping the aircraft the right way up and maintaining VMC, too.....
Alternatively, follow Whirly's suggestion and use any nav-aids available!
FFF
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