Actually not true, all Permit (including microlight) aircraft are required to fly in sight of the surface at all times (at-least in the UK), also clear of cloud below 3,000ft or 1000ft/1500m clear above 3,000ft.
Also the 1500m rule only applies below 3000ft / 140kn and within sight of the surface - ANO Rule 26 (2) (b)(ii) and outside of controlled airspace - it's 5km inside controlled airspace (Rule 25 (2)(c)(i)), and wouldn't be available above an overcast under any circumstances - that becomes IFR.
But, 3km (5km above 3,000 ft) which is the privilege of a normal PPL (no IMC or IR) is still very poor visibility - nonetheless, for a microlight flying typical tight circuits at the 500ft circuit height typical at a microlight airfield it's perfectly sensible for circuits - and should be safe enough since nobody in their right mind should be flying cross-country that low in those conditions. (Plus the airfield should be marked on the chart).
There is a healthy debate going on at present suggesting that warbirds on Permits (Hunters and the like) which were permitted to fly IMC in military service should be allowed to go IFR in transit. This has been under active discussion with CAA for a few years, and everybody's in favour (especially anybody who has ever flow or encountered a transiting Hunter at low level doing just under 250kn) but there still seems some way to go before even this gets approved and it'll probably be necessary for pilots to have revalidated their IMC/IR on that type.
G
Last edited by Genghis the Engineer; 2nd November 2004 at 15:24.