the system, combined with a beacon, to guide helicop­ters to preselected landing zones in the field. The ap­plication of air support radar devices to helicopter operations enhanced the wing's ability to resupply ground units and move them when rain and fog had previously made helicopter support operations pro­hibitive. With the ASRT, the Marine Corps made a unique contribution to the air war; no other Service had facilities comparable in both accuracy and dis­placement ability.

At the beginning of 1970, MASS-3 had five ASRTs deployed, at Quang Tri, FSB Birmingham near Phu Bai, Da Nang, An Hoa, and Chu Lai. As part of the Keystone Robin Alpha redeployment in mid-1970, III MAP prepared plans to withdraw most of the person­nel of MASS-3 and all of its ASRTs except the one at Da Nang. This plan met strong objection from XXIV Corps, which relied heavily on the Quang Tri ASRT to support the 1st Brigade, 5th Infantry Division (Mech) and Birmingham ASRT to control air strikes for the 101st Airborne Division in northern MR 1. The Army so valued the AN/TPQ-10 that, according to General Armstrong, "If the Army commanders had had their way, our AN/TPQ-10 would have been out there until they left." After extensive discussions, the Marines agreed to remove MASS-3 from the Keystone Robin Alpha troop list and keep three ASRTs at Quang Tri, Birmingham, and Da Nang. These ASRTs con­tinued in operation until the final Marine redeploy­ment in May 1971.*62

* For the role of the Quang Tri ASRT in Operation Lam Son 719, see Chapter 11.