if one just 'lets go' of the controls. Causes of retreating blade stall Retreating blade stall is more likely to occur in a helicopter when the following conditions exist either alone or in combination: High gross weight High airspeed Low rotor RPM High density altitude Steep or abrupt turns Turbulent ambient air Recovery Recovery includes lowering the collective to reduce the blade angle of attack, followed by application of aft cyclic to reduce airspeed. References Rotorcraft Flying Handbook: FAA Manual H-8083-21.'', page 11-6. Washington, D.C.: Federal Aviation Administration (Flight Standards Division), U.S. Dept. of Transportation, 2001. . Helicopter aerodynamics Aviation risks