General Cushman's headquarters urged the installation of new radar beacons at Con Thien and KheSanh to improve accuracy when targets were within the 3-kilometer safety zone. Initially, the 3d AirDivision endorsed this concept but upon further study, General Wells decided against it. The beaconswould be vulnerable to enemy fire and could be masked by the towering hills of Quang Tri.
To the Marines, Con Thien still seemed a doubtful precedent, and General Cushman'sheadquarters remained wary of close-in B-52 strikes. If there was to be one test rather than aseries of strikes that gradually drew closer to Khe Sanh, the general suggested dropping thebombs close to one of the satellite outposts so there would be no "destruction of a vital area ifmiscalculation occurs." Even if the bombs were dropped near an outpost, the Marine commandwanted two evaluation runs, with a single bomb dropped each time, so that an aerial observercould radio any necessary adjustments before the bomber sent the remaining 106 bombsscreaming earthward.
A test mission took place on 26 February without benefit of either evaluation runs orsupplementary equipment. A single B-52, with a second Stratofortress as its backup, took offfrom U Tapao carrying 108 500-pound bombs. One Skyspot station checked to make sure theplane's electronic beacon was working properly, directed the bomber to the initial point for itsbomb run, and then monitored the run itself in case the second Sky-spot ground station, whichtook over at the initial point, should break down. No equipment failure occurred, however, andthe test proved that what had happened accidentally at Con Thien could be repeated successfullyat Khe Sanh.
Four close-in missions were flown the following day. As in the test, all bombs fell within thetarget boxes, and though the detonations shook the earth at Khe Sanh, there was neither injury tothe defenders nor damage to bunkers. The spectacle of hundreds of bombs exploding almostsimultaneously brought some of the Marines out of their shelters to cheer the B-52's. All theattacks caused secondary explosions or fires, lasting in one instance for 2 or more hours after theraid.
During March, close-in attacks by B-52's became routine. That month the 3d Air Division flew444 such sorties throughout South Vietnam. In April, with the siege of Khe Sanh broken, thenumber of close-in B-52 sorties declined to 48.
The B-52's and Skyspot proved their accuracy. “During the 589 close-in sorties, there was no USdamage.” 
Close-in bombing may have been a deciding factor in the battle:
General Abrams reported to Admiral Sharp that the Admiral's change in the Arc Light minimumseparation criterion "was quite possibly the deciding factor at Khe Sanh." Abrams added: "Itwas only after the B-52s dropped within 1,000 meters of the fence at Khe Sanh that the enemyshowed signs of crumbling. Prisoners revealed they had been briefed that B-52 aircrews wereprohibited from bombing within three kilometers radius of the fence to be safe." 
 Head, WAR FROM ABOVE THE CLOUDS, Air University Press, Maxwell AFB,
July 2002, pg. 32
 Matignetti, USAF, “To Bomb or Not to Bomb” (Air University, Maxwell AFB 2006 ) 12