Air Support Operations Center located within the corps headquarters. As the number of U.S. and VNAF aviation organizations assigned to I Corps grew and the total number of missions multiplied, it became necessary to modify the system of coordination and control. In accordance with a ComUSMACV directive, I Corps headquarters created an Aviation Headquarters Operations Center (AHOC) to oversee the employment of Marine and Army aircraft in the CTZ. The AHOC, which was composed of a senior Army representative, a senior Marine representative, and an operations section, was to be directed by the Commander, Task Element 220.127.116.11. Formally stated, its primary mission was to "plan, direct, and control the employment of all Army and Marine Corps Aviation Units and aircraft operations in direct support of I Corps." The newly organized AHOC was also ordered to "participate in, and provide assistance to operational planning and the coordination of employment of USA/USMC Aviation with VNAF/USAF tactical air." 6 The AHOC, therefore, was formed to supplement rather than replace the older Air Support Operations Center, which continued to direct and control all U.S. Air Force and VNAF operations over the northern provinces. It was under this arrangement that U.S. Marine and Army aviation units operated after mid-1963.
HMM-261's Marines began encountering systematic Viet Cong resistance to their operations shortly after their first combat missions in early June. A 21-aircraft assault mission into the mountains west of Da Nang was aborted on 6 July when the Marine pilots discovered that the Viet Cong had obstructed the two available landing zones with upright stakes. While inspecting one of the landing zones on a low. pass, a helicopter was hit in the forward fuel cell by Communist small arms fire. The damage to the aircraft was not serious enough to force a landing, but the pilot of an escorting U.S. Army UH-1B was mortally wounded while attempting to suppress the ground fire.
Ten days after the enemy forced the cancellation of the assault mission west of Da Nang, HMM-261 suffered its first aircraft loss in Vietnam. The crash, which was later attributed to mechanical failure, occurred about 37 miles southwest of Da Nang while one of the squadron's helicopters was on a routine logistics mission. Six passengers, two American advisors and four ARVN soldiers, were injured in the accident. The squadron commander dispatched two other UH-34Ds to the scene of the crash to evacuate the wounded and insert a salvage team. The badly damaged aircraft was assessed as beyond repair and was destroyed.
In the second week of August, officers from HMM-261 and the task element's staff (under the command of Colonel Gomez) met with American and Vietnamese officers at I Corps headquarters to plan a large-scale heliborne retrograde movement. The planned helilift was to mark the culmination of Operation LAM SON XII, a three-week long offensive by several battalions of the 2d ARVN Division against Communist infiltration routes in Quang Nam Province along the Laotian border. Although not encircled, the ARVN battalions had encountered increasing Viet Cong pressure since early August. I Corps authorities feared that unless their units were withdrawn promptly they might be cut off from the few landing zones that existed in the rugged operations area.
As planned, the retrograde operation involved helilifting some 1,300 troops with their artillery and equipment to Thuong Due, a government-held town situated 30 miles southwest of Da Nang along the Song Vu Gia. The operation plan called for the commitment of 20 Marine helicopters, 18 of which would participate in the actual troop lifts. The two extra UH-34Ds would be used in the event it became necessary either to replace helicopters assigned to the troop lift or to conduct search and rescue operations for downed aircraft. Three VNAF UH-34s and two U.S. Army unarmed UH-lBs were designated by the I Corps headquarters to assist HMM-261 with the helilift.
The Da Nang Air Support Operations Center assigned a variety of other aircraft to support the operation. These included two VNAF T-28s, one FARM GATE B-26, and two U.S. Army UH-1B gunships. These aircraft would share the task of providing close air support for the troop lift. A Marine 0-1B was scheduled to perform weather reconnaissance missions.
The entire air operation was to be coordinated from two aircraft. An American forward air controller in a VNAF observation plane was to direct all air strikes while overall control for the multi-service, bilingual effort was to come from a U.S.