With the field closed to C-130s, a U. S. Air Force innovation--the Low Altitude Parachute Extraction System or LAPES--was put into effect. This self-contained system, which had been used extensively during the renovation of the airstrip in the fall of 1967, enabled the aircraft to unload their cargo without landing. When making a LAPES run, the Hercules pilot made his approach from the east during which he opened the tail ramp and deployed a reefed cargo parachute. Prior to touchdown, he added just enough power to hold the aircraft about five feet above the ground. As the plane skimmed over the runway and approached the intended extraction point, the pilot electrically opened the streaming chute which was attached to the roller-mounted cargo pallets. The sudden jolt of the blossoming chute snatched the cargo from the rear hatch and the pallets came to a skidding halt on the runway. The pilot then jammed the throttles to the firewall, eased back on the yoke, and executed a high-angle, westerly pull-out to avoid ground fire while the Marines moved onto the runway with forklifts and quickly gathered in the supplies. The system was quite ingenious and allowed the aircraft to pass through the V-ring in a matter of seconds.[37] Even though the airmen could not control the skidding pallets after release, some pilots perfected their individual technique and were able to place the cargo on a 25-meter square with consistency. On one occasion, however, an extraction chute malfunctioned and the cargo rocketed off the western end of the runway; the eight-ton pallet of lumber smashed into a messhall located near the end of the strip and crushed three Marines to death.(120) Another technique--the Ground Proximity Extraction System or GPES--was also used but to a lesser degree than the LAPES. (15 GPES deliveries during the siege as compared to 52 LAPES.) Both utilized the low approach but with GPES the cargo was extracted by a hook extended from a boom at the rear of the aircraft. As the C-130 swooped low over the runway, the pilot tried to snag an arresting cable similar to the one used on aircraft carriers; only his hook was attached to the cargo bundles and not the plane. Upon engagement, the pallets were jerked from the rear hatch and came to a dead stop on the runway. With the GPES, the chance of a pallet skidding out of control or overturning was greatly reduced. The only problem that occurred was not with the system itself but with faulty installation. The Marines who initially emplaced the GPES were frequently chased away from their work by incoming mortar rounds and, as a result of the periodic interruptions, the cable was not anchored properly. The first C-130 that snagged the wire ripped the arresting gear out by the roots. After the initial bugs were remedied, the system worked so successfully that, on one pass, a load containing 30 dozen eggs was extracted without a single eggshell being cracked.(121)