The Marines quickly learned the value of utilizing the OE-1 in conjunction with their helicopter operations. Three single-engine, two-man aircraft, a detachment from Marine Observation Squadron 2 (VMO-2), proved remarkably versatile in day-to-day operations over the delta. Primarily, they were used in daylight visual reconnaissance, usually to study objective areas and the approach routes which the helicopters would later use. Sometimes their crews were called upon to photograph proposed landing zones for briefing purposes. Often the aircraft’s radios were used to relay messages between various ARVN ground units which were operating beyond the range of their radios. Equipped with two frequency-modulated (FM) radios for work with ground stations and one ultra high-frequency (UHF) radio for communicating with other aircraft, the OE-1 was perfectly suited for controlling helicopter landings. The Marine aviators also found that, unlike their helicopters, the observation aircraft did not arouse suspicion in the area over which it flew. This advantage was due probably to several factors. First, the Vietnamese Air Force (VNAF) routinely operated similar aircraft over the entire region; secondly, the enemy could not readily determine whether the OE-1 was on a reconnaissance mission or merely flying from one point to another; and finally, the small aircraft made little noise. Given these characteristics it was no accident that the helicopter squadron relied on the observation aircraft more and more as the pattern of operations unfolded. [Illustration: _Vietnamese infantrymen disembark from HMM-362 helicopters and move toward treeline in one of the first helicopter assault operations attempted by a Marine unit in the Mekong Delta. (Photo courtesy of Lieutenant Colonel James P. Kizer, USMC)._] Shortly after their arrival in Vietnam, the Marines of HMM-362 began experimenting with one of the more imaginative techniques developed in the early stages of the intensified U.S.-GVN counterinsurgency effort. Marine air crews had noticed that the enemy often managed to elude the larger ARVN units by fleeing the operations area in small groups. Even the smallest breach between ARVN units seemed to allow large numbers of guerrillas to escape into covered or heavily populated areas where they became impossible to find. Colonel Carey and Lieutenant Colonel Clapp devised a plan to prevent escapes of this nature. Their idea was to have a flight of four Marine helicopters loaded with about 50 ARVN soldiers circle above the contested area. This so-called “Eagle Flight” would be on the alert for any Viet Cong attempting to evade the ground forces. Once the enemy was located, often by the OE-1 observation aircraft, the helicopters would land the Vietnamese soldiers at a position where they could block his escape. The Marine commanders felt that the adoption of such a tactic would increase the effectiveness of the ARVN’s helicopter assault operations.