Gentlemen,A two-fold question:For a flight KTNT to KATL, I have set, as an example, weather in FS9 to "Major Thunderstorm", and although I see no clouds above FL270,I see the airspeed jumping up & down, and the engines spooling constantly up/down 83.5->83.9 up & down to maintain MCP Speed setting. (.76 M)By the way, the FMC is doing a pretty damn good job of holding course (credit to PMDG)!My question is, does FS9/2004 simulate CAT (Clear Air Turbulence)? I know *something* is occuring, because if I set weather to "Clear Skies (Clears all Weather)" - the aircraft stops wavering and the airspeed stabilizes immediately. As I said above, the way it is now, with clear skies, the engines are constantly spooling up/down to maintain the airspeed selected on MCP.Part 2 of my question is, more importantly, in real life, assuming an extended duration of CAT, is it harmful for the engines to be constantly cycling power like this every few seconds? i.e. - i realize it is not a normal condition, but let's say, for 30 minutes of constant duration of CAT, could they be screwed up doing this?cheers!Josh

Josh,Quick answers to your two-fold question:Yes I think FS9 is capable of simulating CAT. If CAT is encountered you should reduce speed to maximum trubulence penetrating speed which is 0.73 I think. You could set the A/T for N1 mode which means you would reduce the A/T hunting to keep speed. Note. Your speed can drop in this configuration. Constant monitoring is of uttermost importance I would guess. Observe that these are just my qualified beta test driver thoughts. Would be interesting to hear what a real world driver would do! ;-)EDIT:The OPSMNL states that during light to moderate turbulence the A/P and/or A/T may stay engaged. Increased thrust lever activity can be expected. Short time airspeed excursions of 10 to 15 knots can also be expected. Set Passenger signs ON.For severe turbulence the OPSMNL recommends A/T DISENGAGE, A/P to CWS for both pitch and roll. If sustained trimming occurs then disengage A/P. Engine start levers to FLT. THrust manually set for phase of flight.Hope it helps,

Mats,Thanks for the reply!By the way, what exactly does putting the engines to FLT mode do vs. CONT do? cheers,Josh

Josh,Directly from the OPSMNL:8<-- snip --CONT