Research has identified numerous determinants leading to the success of new product development (NPD) projects. However, which particular determinants carry more importance when developing high-novelty projects under tight time constraints have yet to be clarified. We study the development of ECJ-400 of Eclipse Aircraft Company, a highly innovative new jet airplane that was designed and built in a very aggressive 229-day timetable. Through an in-depth case analysis using interviews with members of the four companies involved in the design, manufacturing, and flight testing of the airplane, we enquire about the underlying factors that led to the successful creation of this product. Propositions were formulated and then depicted respectively through the development of a casual network diagram. Our study contributes to the NPD speed literature by highlighting the particular interrelationships between determinants that are influential toward highly novel time-pressured NPD projects.