Hi,I have a small problem. I usually use IAS both in climb and desend. now doing des when I select a lower speed i.e. going from 200kts to 160kts the plane starts to climb quite fast - over 1000fpm. I know "Fi-fi" is NOT a Jetstream, but the A/P shouldn't climb to loose speed.for ref: the JS4100 in FSX and "fair weather".Thanks,Martin

... the A/P shouldn't climb to loose speed.

In IAS mode the AP will adjust rate of climb/descent to match the target airspeed - climbing if necessary.The solution is to bring back power, then come back slowly on the IAS setting so you maintain the descent rate you want.

As Tom said, this is perfectly normal. IAS mode will adjust pitch as necessary, even if it means climbing when you want to descend.The best technique is to set use VS mode, and set a VS that allows you to decelerate with idle power. Once you've bled airspeed down to your target speed, push IAS and continue to descend with idle power. Nice and smooth for the pax that way.Nick

When playing with the IAS descent feature during testing, I developed a method that works real smooth: Set up the ALT and ALTSEL, pull the power back from cruise power to descent (I prefer 40% Torque but any decrease will work) but still on ALT mode holding cruise altitude. When aircraft slows to desired IAS press the IAS mode button and down you go. I would descend at 200KIAS to allow me the flexibility of extending Flaps9 if I am descending straight down into an approach.