Originally Posted by
eckhard
.... What is remarkable, however, is that there were no handling or performance issues that worried us. Some time later I discovered that Boeing conducted tests using wooden shapes attached to the leading edges of the tail surfaces during certification, in order to show that TAI of these areas was not necessary..
Not just Boeing. That's precisely what the regulations require you to do - if you want to be approved for flight into known icing condition you, not surprisingly, have to show that the aircraft can in fact safely fly in those conditions. So everyone does it, one way or another.
However just because a part of the aircraft is not de-iced or anti-iced does not mean it's ok to take off with ice there. All critical surfaces need to be clean for takeoff, whether they have provision for de-icing or anti-icing in flight.