Airdrop in Hiep Duc Valley

 Ben H. Swett, Colonel USAF (Retired)

I was a C-123 navigator in the 315th Tactical Airlift Wing, Phan Rang, Vietnam

19 May 1970 -- A crew from our wing got shot up while trying to airdrop supplies in the Hiep Duc valley. They came in straight and level, up the valley under the clouds, and ran into a flak-trap. The pilot and navigator were wounded slightly. Fortunately, no one was killed. They jettisoned the pallets short of the drop zone and climbed into the clouds. The FAC called in fighters to drop napalm on the pallets, to keep the enemy from getting the supplies.

I got a phone call at 8 p.m. saying I was scheduled to lead a flight in there tomorrow, and spent the next several hours studying maps and Intelligence reports. The Hiep Duc valley is oriented east-west, about 2000 feet deep, and only about a mile wide at the bottom. Monsoon clouds covered the tops of the mountains. There were known or suspected clusters of enemy guns both ways in the valley.

I wanted to minimize our exposure to both clusters of guns, and I knew that a C-123 could descend very steeply with full flaps extended, so I drew up a graph of distance and terrain elevations to come in from the south and descend through the clouds into the valley cross-wise. The number two aircrew (Major Walton) elected to come in from the south under the clouds through a gap in the mountains and do a descending S-turn to the drop zone.

20 May 1970 -- Airdrop mission. The pilot was Major Don Rice, and the copilot was 1st Lt. Scott Bohner. We departed Phan Rang at 0624 and went to Chu Lai.

Ground crews at Chu Lai loaded our aircraft with four 2000-pound pallets, each rigged with three large parachutes. I knew the troops were in trouble when I saw the pallets were packed with water bottles, food, medical kits, blood plasma, M-16 and machine-gun ammunition, and mortar rounds. The on-load chief said he was told to put only four pallets on each aircraft, because the drop zone wasn't long enough for more than that. He tied the pallets together with two turns of 80-pound break tape to "shorten the stick" (keep them from spreading out so far along our track).

Army Intelligence officers told us the drop zone was a small, isolated camp where 500 ARVN troops and their U.S. Special Forces advisors had been under siege for eight days, but they weren't sure which bump in that valley was the drop zone. I said I had to talk with the FAC to know exactly where the drop zone was located. He was flying over the valley, but he was due to refuel at Chu Lai, so we waited for him.

The FAC knew precisely which hill was the drop zone and pointed it out on the map. The entire camp was 75 yards east-west by 150 yards north-south, on top of a small hill near the north side of the bottom of the valley. At that point, the valley was too narrow for us to come in from the south, but to put all four pallets in the drop zone, the drop heading had to be north, so I planned to come in from the south-east and turn north when we were half-way down inside the valley. The drop sequence was to roll out of the turn and level off 10 seconds prior to release, 300 feet above the drop zone, aim just inside the south end of the drop zone, and then do a hard left climbing turn immediately after release to keep from running into the north wall of the valley. I briefed both crews and the FAC, and we discussed every step of the mission plan.

We took off and climbed to 8000 feet. After we leveled off, we couldn't see the ground from the cockpit because the tops of the clouds below us blocked our view from that angle. I climbed down in the cargo compartment, stuck my head out the side window, and looked straight down to see where we were. I took my last position fix over a  bend in a river and started my stopwatch, climbed back up in the cockpit, used dead reckoning to compute our flying time to the start descent point, and gave the pilots the heading, airspeed and rate-of-descent (1500 feet per minute). At the computed stopwatch time, I said, "Stand by to start descent ... ready ... ready ... now."

Coming down through the clouds took what seemed like a long time, but Major Rice flew the heading, airspeed and rate-of-descent precisely, and we popped out right where we were supposed to be, descending just inside the south wall of the valley. I said, "Start the smoke." The FAC put a white phosphorous rocket 200 yards south of the camp, and the Special Forces advisor in the camp started continuous red smoke on the aiming point. That piece of coordination eliminated the possibility that I might not see the camp, or not see it soon enough to complete the drop.

The Special Forces advisor said, "He's going the wrong way. Doesn't he see us?" The FAC said, "He planned for a turn. Stay off the radio." We rolled into the right turn to the drop zone about 45 seconds after we popped through the clouds.

We flew almost over a 14.5 mm heavy machine gun about 10 seconds before release. He fired a long burst, but he missed us because we came from a direction he didn't expect. He only had 80 seconds from the time we popped through the clouds to get his big gun turned around, or 35 seconds from the time we turned toward him, and at the time he fired, we were rolling out of the descending right turn and leveling off.

When I called, "Green light!" Major Rice fire-walled the throttles and pulled the nose up, Lt. Bohner toggled the jets to 100% and the loadmaster released the strap that restrained the pallets. We accelerated and pulled up so fast that I had to hold on to the pilots' seats with both hands to keep from falling out the back of the aircraft.

Three seconds after "Green light" the loadmaster said, "Load clear!" and Major Rice did the climbing left turn so tight and steep that the aircraft started shuddering and the stall warning sounded, but he eased the nose down a little and flew us out of there. We cleared the north wall of the valley by about 500 feet.

While we were still in the climbing turn, we heard the FAC say, "Do you want me to mark that gun?" Another voice said, "I saw it fire. I'm on it," and we watched a Navy A-4 put a cluster bomb on the machine gun. It didn't fire at our number two aircraft.

The FAC said we dropped our four pallets 50 yards beyond the aiming point, 100% recoverable, and the number two aircraft dropped his four pallets 25 yards left of the aiming point, 100% recoverable -- which meant that all eight tons of supplies were inside the camp.

A few days later, our headquarters received a letter from the Army that said our airdrops on 20 May were instrumental in saving the lives of 500 men and restoring their ability to fight off attacks, and that a relief force had reached them.

1970 Log