Perhaps we should mention that it's mainly the breakdown in the aerodynamic properties of the wing (and tailplane) by ice (thereby decreasing lift and increasing drag) which creates potential control problems rather than the weight of ice.
As has been previously stated some a/c do not need to have de-icing systems fitted to the tailplane.
There have been previous cases in aviation history where control of the a/c has been lost when landing flap was selected with tailplane icing. Essentially the tailplane forces balance the a/c in the pitching plane. When flaps are extended this affects the trim which in normal conditions is not a problem but significant ice on the tailplane coupled with the trim change can lead to loss of control.