Although the C-141 Starlifter was being introduced, they believed that a much larger and more capable aircraft was needed, especially the capability to carry outsized cargo that would not fit in any existing aircraft.
Aínda que fora introducido o C-141 Starlifter, sentíase que se precisaba un avión máis grande e capaz, especialmente con respecto á capacidade de levar cargas non estándares que non se adaptaban a calquera avión.