Marine helicopter support for government forces in I Corps encountered a brief interruption shortly after the new year began when HMM-163 was replaced by a fresh UH-34D squadron. Marine KC-130s shuttled between Okinawa and Da Nang for several days during the second week of January bringing the officers and men of HMM-162 to Vietnam and returning with members of HMM-163. The change-over of units was completed on 11 January when Lieutenant Colonel Rathbun officially transferred his squadron’s aircraft and maintenance equipment to the newly-arrived unit. In the five months and ten days since they initiated operations at Soc Trang, “Rathbun’s Ridge Runners” had amassed an enviable combat record. The squadron’s crews had flown a total of 10,869 hours, 15,200 sorties, and had lifted over 25,216 combat assault troops and 59,024 other passengers. In one month alone (August) they had established a Marine Corps record for medium helicopter squadrons by flying 2,543 helicopter hours. These records had not been set without risks, however. During the course of their operations in the Mekong Delta and in I Corps, helicopters operated by HMM-163’s crews had been hit on 32 occasions by Communist small arms fire.[9-2] Moreover, the squadron had become the first Marine unit to suffer combat casualties in the Vietnam conflict. HMM-162, led by Lieutenant Colonel Reinhardt Leu, the veteran Marine aviator who had commanded the squadron during the recent deployment to Thailand as part of the 3d MEU, began full-fledged combat support operations the same day that the last of Rathbun’s squadron departed Da Nang. HMM-162’s crews, many of whom had participated in similar operations around Udorn the previous summer, limited their early flights to routine resupply missions and a few medical evacuations. Such missions enabled the squadron’s personnel to become better acquainted with the terrain over which they would operate during the next six months. The new squadron participated in its first major combat troop lift on January 19, when a break in the monsoon allowed the 2d ARVN Division to execute a heliborne operation into the mountains about 15 miles west of Da Nang. Eighteen Marine UH-34Ds lifted 300 ARVN troops into three separate landing zones near a suspected Communist base area. The squadron’s pilots and crews encountered their first Viet Cong opposition during this troop lift. Upright bamboo stakes obstructed one of the landing zones while at another the enemy fired at the Marine aircraft with small arms. Although two UH-34Ds were hit, none were shot down and the mission was completed successfully.