Shortstripper,
I agree with you that it is easy to navigate in poor viz in, say, a Luton Minor - but I think IO540 is correct that the techniques taught at PPL level don't work in this viz - even more so at low speed. As I see it, there are two problems with flying in very low viz - navigation, and control of the aircraft.
First, navigation:
The ded reckoning techniques which are taught at PPL level will work perfectly well in any weather, including in IMC.
However, ded reckoning is only as good as the wind forecast you have to work with. If the forecast is not accurate, you have to back the ded reckoning up with some other means of navigation - map reading being the one which is taught at PPL level, and which should always be the primary one for VFR flight.
The techniques are based on the idea that if you follow your ded reckoning plan, you will be close enough to your track to be able to see features which are on or near your track, estimate how far off track you are, and make corrections. As the viz decreases, a number of problems arise. First of all, if you are not within a couple of miles of your track, or easily recogniseable features near your track, you will not see those features. The slower you travel, the more effect the wind will have on you, therefore the further off-track you might be if the wind forecast is wrong - so I would guess this particular aspect of navigation would be more difficult in a slower aircraft. (I believe that fast jet pilots have very few problems ded reckoning because they go so fast the wind has very little effect on them whatsoever, but maybe someone else can confirm?)
Also, it is more difficult to possitively identify features, because it is not so easy to compare a feature to its surroundings and see combinations of features when the surroundings and nearby features are further away than the limits of the viz - this, though, I don't think is affected by speed.
So what we need is an alternative method of navigation. The easiest way, I find, is by using line features. (I'm quite lucky in that right now I fly near a very big line feature called "the coast", which makes life very easy!) My first choice option is to follow line features. If that's not possible, then I would fly towards a line feature, making sure I keep to one side of where I would like to reach the line feature - typically to the right hand side. That way, when I reach the line feature, I know I have to turn left to arrive at my destination. In contrast to ded reckoning, this technique does work very well at low speeds, which is why if I'm anything much faster than a Luton Minor I would put some flaps down and use a "slow, safe cruise". The other thing I would do when planning a trip in this weather is make sure I am very aware of any obstructions along the way, and either fly at a height above the legal IFR MSA (even though I am VFR), or if that's not possible, find another way of definitely staying out of the way of the obstructions (e.g. knowing that the obstruction is to the north of the motorway, so remaining south will keep you clear.)
The second issue of how to control the aircraft without a horizon is a completely different one, and comes down to a combination of visual flying and instrument flying, very similar to what you do at night.
FFF
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