Much of I Corps began experiencing improved weather conditions during the first days of April. Relying on helicopter support, the ARVN resumed its offensives into the rugged mountainous regions. On the 6th a combined Allied helicopter flight lifted 42 ARVN soldiers from Tam Ky to a landing zone about 18 miles directly west of Quang Ngai. An Army UH-1B was shot down by Communist fire during the operation. Shortly after the crash, one of HMM-364’s helicopters landed to rescue the crew and strip the weapons from the downed aircraft. Marine mechanics then helped Army aviation technicians disassemble the UH-1B whereupon it was suspended beneath an Army UH-37 (a twin-engine, piston-powered, heavy helicopter manufactured by Sikorsky) in a specially designed sling and helilifted back to Da Nang for repairs. Lieutenant Colonel La Voy’s squadron suffered its first combat aircraft loss on 14 April. The incident occurred after one of HMM-364’s helicopters was hit in the engine by Viet Cong fire while attempting to evacuate wounded Vietnamese infantrymen from a hillside landing zone about 40 miles west of Da Nang near the Laotian border. Struck while taking off, the UH-34D plunged 150 feet down the steep hillside and crashed through the jungle into a stream bed. One Marine manning an M-60 machine gun suffered a broken leg in the crash. The other crew members and passengers, however, were able to carry him up the hill to the ARVN landing zone. Heavy thunder showers prevented rescue for two hours, but the weather finally broke and the men were helilifted to Da Nang. The aircraft was destroyed the next day. Four days after this incident, HMM-364 committed all available aircraft to a battalion-size heliborne assault into rugged northwestern Thua Thien Province. The ARVN’s objective was a mountainous area on the northern rim of the A Shau Valley, a 30-mile-long, two-mile-wide trough whose location adjacent to the Laotian border invited Communist infiltration. Although enemy activity would eventually force the government to abandon its string of outposts in the valley, the issue of control of the area was still unresolved in early 1964.