 The overland supply route to the base had been cut off , and airborne resupply by cargo aircraft became extremely dangerous due to heavy North Vietnamese antiaircraft fire . Thanks to innovative high @-@ speed " Super <unk> " , which utilized fighter @-@ bombers in combination with large numbers of supply helicopters , and the Air Force 's utilization of C @-@ 130 Hercules cargo aircraft employing the innovative <unk> delivery method , aerial resupply was never halted . 
