By the end of the year HSA had submitted a proposal to the Ministry of Defence based on the design concept, and in early 1970 the RAF issued Air Staff Target (AST) 397 which formalised the requirement for new trainers of this type.
年底，HSA基于该设计理念向国防部提交了一份建议，1970年初，RAF签署了AST397，正式提出对这种新的训练机需求。