Set in 1999, this case allows students to put themselves in the positions of both Airbus and Boeing as Boeing considered how to respond to Airbus's decision to announce its plans to proceed or not with the $10 billion development of the world's first commercial superjumbo jet, the Airbus A3XX. Boeing was considering a development effort to "stretch" its 747 jumbo jet into a larger superjumbo version, the 747-X. At the time, the two companies' widely available 20-year forecasts for jumbo- and superjumbo-jet demand were particularly divergent. In light of this very public "agreement to disagree," Boeing could pursue several alternatives, all of which were related to Airbus's decision about whether or not to develop the A3XX. This case presents an opportunity for students to make a real downstream decision. It was prepared as a final exam for an introductory decision analysis course involving subjective probability assessment, decision tree modeling, simulation, real options, and game theory. In the analysis of this case, a student is expected to utilize ideas from all five of these areas.