crews of the 0-1 B observation aircraft. Later in the month a photo lab was completed to facilitate the rapid processing of the photographs. By the end of the month the Marines were also being provided with high altitude photographic coverage of some objective areas taken by U.S. Air Force reconnaissance jets.
The tempo of Marine helicopter operations began to quicken in early April with the advent of sustained periods of clear weather. On 13 April, HMM-162 participated in a major heliborne assault in which 435 2d ARVN Division troops were lifted into a suspected Communist stronghold in the mountains along the Song Thu Bon, about 30 miles south of Da Nang. As in most troop lift missions, the Marine 0-lBs provided reconnaissance and radio relay support. For the first time in the war Marine transport helicopters were escorted by helicopter gunships, the UH-1B Iroquois (a single-engine, turbine-powered utility helicopter built by the Bell Helicopter Company). Five UH-lBs from a detachment of the Army's Da Nang-based 68th Aviation Company, armed with M-60 machine gun clusters and 2.75-inch rockets, joined the VNAF fighter bombers to conduct preparatory airstrikes on the landing zones.
The initial landing met no enemy resistance but later in the day action in the operational area intensified. A Marine UH-34D was hit by eight rounds of enemy small arms fire while attempting to evacuate wounded South Vietnamese soldiers and U.S. Army advisors from a landing zone near the point where the ARVN forces had been landed that morning. With the co-pilot, First Lieutenant John D. Olmen, wounded, the badly damaged aircraft force landed in the Vietnamese position.
Two other Marine helicopters were dispatched to the scene to pick up the Marine crew and complete the evacuation. They managed to evacuate Lieutenant Olmen, a wounded American advisor, and one dead and four wounded ARVN soldiers without incident. On a return trip to pick up more wounded, however, one of the two UH-34Ds suffered heavy damage from Viet Cong fire. In this incident the crew chief. Corporal Charley M. Campbell, was wounded in the thigh, chest, and back by small arms fire, and the aircraft was forced to land near the first downed helicopter. The accompanying UH-34D landed, picked up Campbell, and returned him to Da Nang for emergency treatment. Repair teams were helilifted to the position on the afternoon of the 13th, and began repairing both helicopters. One was able to return to Da Nang later that day but the other required extensive repairs and could not be flown to safety until the 15th.
While HMM-162 repair crews were working feverishly to extricate their aircraft from the predicament along the banks of the Song Thu Bon, another of their helicopters was shot down nearby while supporting the same operation. This aircraft was hit four times while approaching an ARVN landing zone located in a small valley about three miles south of the action in which the two helicopters had been lost earlier. After temporary repairs were made, its crew flew the damaged UH-34D to Da Nang where more detailed repair work was accomplished. The number of combat support sorties flown into the mountains by HMM-162's crews rose steadily as the weather improved. Near the end of April, the Marines helilifted three battalions of the 1st ARVN Division into the mountains of Quang Tri and Thua Thien Provinces near the Laotian border. These units were to participate in an extended multi-regiment drive against suspected Communist infiltration routes there. This operation, for which Lieutenant Colonel Leu's squadron provided daily support after the initial landing, taxed the durability of both the Marine crews and their aircraft. For 90 days task element helicopters flew into and out of hazardous landing zones located at elevations as high as 4,500 feet, The majority of these sorties were resupply and medical evacuation missions with the occasional exception being the heliborne displacement of infantry and artillery units when distance or terrain prohibited overland movement. Despite the dangers inherent in helicopter operations conducted over mountainous terrain, the squadron incurred no aircraft or personnel losses while supporting the offensive in western Quang Tri and Thua Thien Provinces.
While his squadron's support of the 1st ARVN Division's on-going drive near the Laotian border continued, Lieutenant Colonel Leu committed 21 UH-34Ds to support the offensive against the Do Xa base area along the southern edge of I Corps. On 27 April, Marine crews helilifted over 567 troops of the 2d ARVN Division into the