Crash crew at Khe Sanh pours foam on a burning CH-46 helicopter following an enemy artillery attack. (USMC Photo A190350)
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)]
Most of the time, however, the low overcast precluded the use of either extraction system and the preponderance of supplies was delivered by paradrops. This technique called for close air/ground coordination and the C-130 pilots relied on the Marine Air Traffic Control Unit (MATCU) at Khe Sanh to guide them in to the drop zones. The Marine ground controller lined the aircraft up on the long axis of the runway for a normal instrument approach and when the Hercules passed a certain point over the eastern threshold of the field, the controller called "Ready, Ready, Mark." At "Mark," the pilot pushed a stop watch, activated his Doppler navigational system, turned to a predetermined heading and maintained an altitude of between 500 and 600 feet. The Doppler device indicated any deviation from the desired track to the drop zone, which was west of Red Sector, and the release point was calculated by using the stop watch--20 to 26 seconds from "Mark," depending on the winds. At the computed release point, the pilot pulled the C-130 into an 8-degree nose-up attitude and 16 parachute bundles, containing 15 tons of supplies, slid from the rear of the aircraft and floated through the overcast into the 300-meter-square drop zone. Under Visual Flight Rules (VFR), the average computed error for the drops was only 95 meters. Even when these missions were executed completely under Instrument Flight Rules (IFR), the average distance that the bundles landed from the intended impact point was 133 meters--well inside the drop zone. On a few occasions, however, the parachute bundles missed the zone and drifted far enough away from the base to preclude a safe recovery. In these rare instances, friendly artillery and air strikes were brought to bear on the wayward containers to keep them from falling into the hands of the enemy. During the siege, Air Force C-130 crews conducted a total of 496 paradrops at Khe Sanh.[38] [(122)]
Although the paradrops were sufficient for bulk commodities such as rations and ammunition, there were certain items which had to be delivered or picked up personally. Medical supplies, special ammunition, and other delicate cargo would not withstand the jolt of a parachute landing. In addition, there were replacements to be shuttled into the base and casualties to be evacuated. With the cancellation of all C-130 landings, this job was left up to the sturdy C-123 Providers of the 315th Air Commando Wing as well as MAG-36 and MAG-16 helicopters. The choppers could maneuver around areas of heavy ground fire, land, unload, take on medevacs, and depart very quickly but their payloads were limited. On the other hand, the C-123s had a larger cargo capacity but were restricted to a more rigid approach and provided better targets both in the pattern and on the ground.[39] [(123)] The Providers, however, required much less runway from which to operate than the C-130s and could land and take off using only 1,400 of the 3,900 foot strip. This saving feature enabled the pilots to make a steep approach, short roll-out, and rapid turnaround. The crews still had to undergo those frantic moments on the ground when the geysers of dirty-black smoke bracketed their aircraft. Nevertheless, the dauntless C-123 crews continued their perilous missions throughout the siege with great success.[(124)]
No discussion of the airlift would be complete without mention of the MAG-36 and MAG-16 helicopter pilots who flew in and out of Khe Sanh daily delivering supplies, delicate cargo, reinforcements, and evacuating casualties. The chopper crews were faced with the same problems that plagued the fixed-wing transports--low ceilings and enemy ground fire--but to a greater degree because of their slow speed and vulnerability. MAG-36 operated primarily from Quang Tri and Dong Ha, and was reinforced from the group's main base at Phu Bai. These valiant pilots and crewmen in their Huey gunships, CH-46 transports, and UH-34s flew long hours, day and night, in all kinds of weather to sustain the Marines in and around Khe Sanh. The CH-53s of Da Nang-based MAG-16, with their heavier payload, also made a sizeable contribution to this effort.[(125)]
C-130 Hercules conducts paradrops west of Red Sector. (USMC Photo A190803)
