The creation of a new aircraft with a specific purpose is a highly labor-intensive and extremely costly challenge. It can be an overwhelming task even for companies with substantial resources. Therefore, modern aircraft manufacturing increasingly relies on developing successful products through the formation of modification parameters for both military and civil aviation purposes. Such developments shorten the time of operational deployment by years and reduce labor costs by millions of dollars. As a result, aircraft manufacturing companies are increasingly pursuing this path. The publication illustrates the way of decision-support models creation applicable at the design stage for dual-use aircraft. To achieve the objectives, such previously developed and proven methods were used as ensuring the aircraft’s weight balance, matching the required thrust with the selection of engines and estimating the cost per aircraft-hour. The effectiveness of using of these decision-support models is illustrated through the examples of aircraft modifications implementation like An-32 → An-132D, An-148 → An-178 and An-77 → An-188. The paper, for the first time, uses such economic indicators for the feasibility of designing dual-use transport category aircraft modifications as costs in monetary terms for the entire lifecycle, including design, prototype production and the entire operational phase, and specific costs as the ratio of total costs to all completed useful work.