Another adjustment--this one in the area of tactics--had been made during the task unit’s first two months at Da Nang. By November the Eagle Flight concept had been tailored to complement reaction force plans which already existed in I Corps at the time of SHUFLY’s relocation. ARVN authorities in the northern corps tactical zone had developed a system whereby their various infantry units were placed on alert for use as heliborne reaction forces. Designated the Tiger Force, the alert unit was staged at its base, ready to react to any tactical emergency. HMM-163 Marines executed one of their earliest Tiger Flights on 7 November in response to a train ambush sprung by the Viet Cong several miles northwest of the Hai Van Peninsula. Four Marine helicopters launched from Da Nang, made an airborne rendezvous with two other HUSs, and proceeded to Hoa My, four miles away, to pick up a 52-man ARVN Tiger Force. The Marines then helilifted the South Vietnamese into a suitable landing zone near the ambush site. The relatively short amount of time consumed in the reaction did not prevent the Communist attackers from vanishing into the surrounding jungle. Generally, however, the tactic was more successful, particularly when the reaction force was used to reinforce a threatened static position or to establish hasty blocking positions in support of ground offensive operations that were already underway. While the task unit encountered few major problems during the early operations from Da Nang, minor difficulties were commonplace. Most often these developed during the execution phase of combat support missions. One that particularly concerned the Marine commanders was the tendency of South Vietnamese units not to prepare properly for scheduled helilifts. To the dismay of the Leatherneck helicopter crews, ARVN activities at the pickup points were usually characterized by confusion. More often than not the Vietnamese unit scheduled to be helilifted had not been organized into heliteams prior to the arrival of the transport aircraft. Given the fact that heliborne operations were still somewhat of a novelty to most ARVN small unit leaders (and to many U.S. advisors) at this stage of the war, these circumstances were perhaps understandable. Nevertheless, lack of prior preparation at pickup points on the part of the ground units often threatened to disrupt the timing of preplanned operations.