The route, five air miles in length, amounted to a round trip of 13 miles because of the detours necessary for purposes of concealment. The aircraft were to take off from a dry river bed southeast of Hill 702 (Map 21) and land near the northwestern rim of the Punchbowl, where the troops would march a mile to their final assembly area. The infantry unit selected for Operation BLACKBIRD was Easy Company of 2/1, commanded by Second Lieutenant William K. Rockey. Lieutenant Colonel Nihart and Major Carl E. Walker, the battalion commander and his executive officer, supervised the daylight rehearsal on the morning of the 27th. Six helicopters lifted 200 men in the overall time of two hours and 10 minutes to a landing site of 50 by 100 feet cleared by a team of the 1st Shore Party Battalion. The troops were proceeding on foot to their assembly area when an antipersonnel mine wounded a man. Nihart called a halt immediately and investigation revealed that the area was filled with mines. Plans were changed to abandon the march, although the landing site remained the same. Operation BLACKBIRD got under way at 1930 on 27 September. The night was dark when the first HRS-1 took off with five combat-equipped men. Three-minute intervals were required between aircraft operating on a shuttle system, so as to avoid the danger of collisions. Different altitudes were assigned to outgoing and incoming helicopters which used running lights only two minutes before entering or leaving the debarkation zone. A total of 223 troops were landed in over-all time of two hours and 20 minutes instead of the nine hours a movement by foot would have required. Nevertheless, some of the results were not reassuring. Rotor wash blew out many of the flare pots lighting the embarkation area, and the battery-powered beach lanterns on the landing site proved inadequate. Pilots were temporarily blinded by the glare on windshields; and artillery flashes bothered them while making their way through three mountain passes. Fortunately, good radio communications aided pilots who had trouble in locating the landing site in spite of night rehearsals. Operation BLACKBIRD remained the only night helicopter troop lift during the war in Korea. “Present equipment,” said the Marine report, “indicates that under present conditions in Korea these night lifts should be limited to movements within friendly territory.”[311] [311] Type “C” Spec Rpt, “The Employment of Assault Helicopters,” Part II, 4. “_To Organize, Construct and Defend_” “The Division continued to organize, construct and defend positions along a 13½-mile front; patrol forward of the MLR and screen rear areas; and maintain one U.S. Marine regiment which could not be committed without authority from X Corps in a reserve area 17 miles behind the lines.”