klos:
Would a Pro kindly explain the procedure for recovering from an uncommanded reverse thrust in the cruise.
Many thanks
Depends on the aircraft.
DC-8: Reverse Thrust Lever - FORWARD IDLE; Emergency Stow Pump - ON; If reverser fails to stow: Engine - SHUTDOWN
Other aircraft without an emergency stow pump: Thrust Lever - IDLE; If the reverser doesn't stow - Engine - SHUTDOWN
Essentially, select idle power and hope it stows. If not, engine shutdown is necessary to reduce asymmetry. Most airplanes these days don't have buckets that reverse core air. Only the fan air is reversed, so the drag increase and asymmetry is less.