the yc-15s completed a 600-hour flight test program in 1977. by this point, the seeds of the amst program's demise had already been sown. in march 1976, the air force chief of staff, gen. david c. jones, asked the air force systems command to see if it was possible to use a single model of the amst for both strategic and tactical airlift roles, or alternatively, if it was possible to develop non-stol derivatives of the amst for the strategic airlift role. this led to a series of studies that basically stated that such a modification was not easy, and would require major changes to either design to produce a much larger aircraft.