Frozen Chosen: With the path to Hungnam blocked at Funchilin Pass due to the blown bridge, the US Air Force stood tall to deliver the means for the Marines to continue their fighting withdrawal. At 9 am on 7 December, eight C-119 Flying Boxcars flown by the US 314th Troop Carrier Wing appeared over Koto-Rl and were used to drop portable bridge sections by parachute. The bridge, consisting of eight separate 18 ft long sections, were dropped one section at a time, using two 48 ft parachutes on each section. Each plane carried one bridge section, weighing close to 2,500 pounds. The Marines needed only four sections, but had requested eight in case several did not survive the drop. The planes lowered to eight hundred feet, drawing fire from the Chinese on the surrounding hills, and the cargo masters began dumping their precious cargo. Each bridge section had giant G-5 parachutes attached to both ends for security if a single chute failed. A practice drop with smaller chutes at Yonpo airfield near Hungnam had failed, but there was no time for more experimentation. It was now or never for the 1st Marine Division. By 1530 on 9 December, four of these sections, together with additional wooden extensions, were successfully reassembled into a replacement bridge by Marine Corps combat engineers, led by First Lieutenant David Peppin of Company D, 1st Engineer Battalion, and the US Army 58th Engineer Treadway Bridge Company enabling UN forces to proceed.  Outmaneuvered, the PVA 58th and 60th Divisions still tried to slow the UN advance with ambushes and raids, but after weeks of non-stop fighting, the two Chinese divisions combined had only 200 soldiers left. The last UN forces left Funchilin Pass by 11 December.