KA8 Flyer - I don't think Bantios' explanation is quite correct. In level flight if you close the thrust levers the airspeed will reduce to a minimum level then the autoflight system will trim the aircraft nose down to descend so as to maintain that speed. Left untouched the aircraft will descend into the ground at that speed. If you attempt to intervene by pulling the stick back you will reduce the airspeed further into the alpha-protection range, then the engines will go to full power to prevent the stall.