I am currently flying to PANC from KLAX. And am over the ocean a few hundred miles away from Anchorage. I have a question regarding anti-ice. I am flying at FL360, and there are patches of clouds above me, and way below me. When do I put anti icing on? Is it only when I am going "through" them? OAT is -16 C, so its very cold up there. Since clouds are above me is it a good idea to make sure no frost gets on my airplane?Thanks,Alex

The lack of heat is only part of the issue. You need moisture to ice up so in clouds or high humidity you should have it on. If it is -16 and your in low humidity conditions it isn't necessary.I don't think I would expect much moisture at FL360 even if there high level clouds. Unless your flying through a towering cumulonimbus!Steven.

Alex,Turn on engine anti-ice whenever the temperature is below 50 degrees Fahrenheit (yes, 50) and there is visible moisture in the air.Wing anti-ice should be turned on only when you detect icing on the exterior surfaces of the aircraft. Some aircraft have icing detection equipment, but most require other means. In FSX, if you're slowing down and can't account for the loss of airspeed, try turning on wing anti-ice.Leaving the wing anti-ice on when there is only the potential for icing can be disastrous in the real world. Wing anti-ice works by inflating leading edge "boots", which cracks the ice to be swept away in the airstream. If ice forms on the boots while they're inflated, there is then no way to break up the ice, and your only option is to descend into warmer air and hope the ice will melt. In winter, that might not work.