Thanks Bladestrike, we are on the same wavelength. I have been trying to source a suitable electric heater for inside the cockpit but even manufacturers can't tell me if their heaters are suitable for use inside a heli. Any pointers? Unfortunately manufacturer specifically does not recommend use of any de-icing fliud on the glazing!! This is echoed very strongly by our chief engineer. Tonight we again had to push the A/c back inside the hangar to demist the screens - not very satisfactory even though it's a mere 2 tonnes between 3 of us!