Even though the Marine air-ground team had been shorn of much of its tactical aviation, what remained was well utilized. Helicopter troop operations had become commonplace by the end of April 1952. That month there were three exercises to further evaluate tactical concepts of helicopter employment. Operation PRONTO, conducted on 5 April, was the first major troop lift in the new I Corps sector. In this maneuver approximately 670 troops of 2/7 and 10,000 pounds of rations were transported by helicopter and truck from the Munsan-ni vicinity across the Han River to the Kimpo Peninsula. Here the reserve battalion served as a counterattack force in a hypothetical enemy landing. Due to the necessity for avoiding the neutrality zone in the Munsan area, round-trip flights averaged about 57 miles. The exercise combined the shortest notice and longest distance of any large-scale helicopter troop movement conducted by HMR-161. It pointed to the fact that a helicopter unit could successfully lift a troop organization virtually as an “on call” tactical tool and without the benefit of previous liaison. Operation LEAPFROG, on 18–19 April, transported one KMC battalion across the Han to the peninsula and lifted out another the following day. The purpose of this test was to determine the feasibility of a replacement movement conducted over water, with “consideration given to the language barrier existing between the troops and the transporting facility.”[53] The six-mile round trip was the shortest troop haul yet made by the transport chopper squadron. Consequently, it took the 12 HRS-1 single-engine Sikorsky aircraft only 3 hours and 26 minutes to complete the exchange of the 1,702 KMC troops. [53] _PacFlt EvalRpt_ No. 4, 10-73. Colonel McCutcheon’s HMR-161 pilots found that their helicopters could carry six combat-equipped Korean Marines instead of five American Marines, due to the smaller size and weight of the average Korean. Since the U.S. and KMC Marine battalions were the same size, the larger load factor for the Korean Marines enabled their unit to be moved faster. In LEAPFROG the language difference proved to be no handicap, since there were sufficient interpreters on hand and the troops were cooperative. Helicopter pilots could use landing sites close together because the terrain was open and the area of operations beyond the reach of Chinese artillery.