EW/C2016/03/02 On 4 March 2015, the flight crew of an ATR72 decided to depart from Manchester without prior ground de/anti icing treatment judging it unnecessary despite the presence of frozen deposits on the airframe and from rotation onwards found that manual forward control column input beyond trim capability was necessary to maintain controlled flight. The aircraft was subsequently diverted. The Investigation found that the problem had been attributable to ice contamination on the upper surface of the horizontal tailplane. It was considered that the awareness of both pilots of the risk of airframe icing had been inadequate.