Going from Frankfurt to Bangkok in the PMDG 747, over Armenia/Georgia I encountered a large belt of thunderstorms at FL330. I was never actually in visible moisture, and avoided all the clouds- there was a sold layer below me, with the "anvils" extending up past my altuitude, but I avoided them. Using ASE, my cloud icing slider is set to a maximum of 75%. I started noticing bad turbulence, so I slowed down to M .78, and from then on the plane flew like a brick. I was stalling, couldn't keep altitude, and could barely keep above 240/250 knots with the engines running constantly at 103%. I was able to descend to FL220, where I could maintain 250 knots and barely keep altitude, with the stick shaker going off all the time. This definitely sounds like icing- but I never flew into visible moisture. Eventually, I gave up and quit after two hours of slogging around at FL220/250 knots, with all anti-icing on, with no improvement. 1. Using ASE, when can I tell that I'm in icing conditions if the plane doesn't come equipped with a detector? There was no visible moisture in the air that I was flying in, so the only safe thing to do would seem to be to keep anti-ice on whenever large clouds are nearby, which doesn't seem too efficient or realistic. If I'm wrong, please correct me. 2. If I get into the above situation, how do I fix it? I kept on for a while with all anti-ice blasting with no noticeable improvement. Should I have kept on descending? IIRC, the TAT at my final altitude was something like -5 C- do I need to go all the way down to an above freezing temperature to get rid of the ice, or should the anti-ice devices be able to clear it? thanks+

The quick answer - switch off ice effects in fs as it is completely unrealistic. It works by increasing aircraft gross weight within fs.If you do want to keep ice effects on then apart from sticking to standard sop and using wing & NAI below -10c you must always have it on when anywhere remotely near thunderstorm buildups, even if your SAT is above freezing.If you have the MD11you will notice the aircraft detects ice buildup for you, no such luxury on the 744.Regards

It works by increasing aircraft gross weight within fs

Hi Rob Not only or marginally..A few hundred pounds of ice may severely affect the aerodynamics. Evidently, it could'nt be a "weight" factor only. Just adding 2,000 lb of fuel or payload doesn't produce such a huge effect. It appears the structural FS icing process drastically decreases the wing lift, above a certain weight but, AFAIK it has not been put in an equation.