DEPARTMENT OF THE AIR FORCE

HEADQUARTERS PACIFIC AIR FORCES

APO SAN FRANCISCO 96553

 

PROJECT CHECO REPORTS

The counterinsurgency and unconventional warfare environment of Southeast Asia has resulted in the employment of USAF airpower to meet a multitude of requirements. The varied applications of airpower have involved the full spectrum of USAF aerospace vehicles, support equip­ment, and manpower. As a result, there has been an accumulation of operational data and experiences that, as a priority, must be collected; documented, and analyzed as to current and future impact upon USAF poli­cies, concepts, and doctrine.

Fortunately, the value of collecting and documenting our SEA experiences was recognized at an early date. In 1962, Hq USAF directed CINCPACAF to establish an activity that would be primarily responsive to Air Staff requirements and direction, and would provide timely and analytical studies of USAF combat operations in SEA.

Project CHECO, an acronym for Contemporary Historical Examination of Current Operations, was established to meet this Air Staff requirement. Managed by Hq PACAF, with elements at Hq 7AF and 7AF/13AF, Project CHECO provides a scholarly, "on-going" historical examination, documentation, and reporting on USAF policies, concepts, and doctrine in PACOM. This CHECO report is part of the overall documentation and examination which is being accomplished. Along with the other CHECO publications, this is an authentic source for an assessment of the effectiveness of USAF airpower in PACOM.

 

Roland A. Campbell, Major General, USAF

Chief of Staff

 

FOREWORD

On 19 December 1970 , a truck park/storage area was discovered on the Ho Chi Minh trail in Laos that led to some of the most significant air strikes of the war in Southeast Asia . From 19 December 1970 to 5 January 1971 , air strikes caused the largest number of secondary explosions from a single target complex in the history of air interdiction on the Ho Chi Minh trail. The loss of equipment and supplies adversely affected North Vietnam efforts to resupply their military forces in Southern Laos , Cambodia , and the Republic of Vietnam .

 

CHAPTER I

INTRODUCTION

On 10 October 1970 , the United States Air Force (USAF) started its northeast monsoon (dry season) interdiction campaign called Commando Hunt V^*. The primary objectives of Commando Hunt V interdiction campaign are to reduce the flow of personnel and material into the Republic of Vietnam and Cambodia to the lowest possible level and to make the enemy pay an increasingly greater cost for his efforts to dominate Southeast Asia (Ref 7AF OPlan-715, 14 Sep 70 , pg 6). Historically, the North Vietnamese intensify their resupply efforts during the northeast monsoon season, so that their combat units can operate with little or no material support from North Vietnam during the subsequent wet season when the enemy's logistic infiltration through Laos is severely affected by bad weather and muddy roads. _1/

Intelligence sources estimated that the North Vietnamese would substantially increase--as compared to Commando Hunt I and Commando III efforts--their supply activities through Laos during the 1970-71 dry season. The enemy logistic system in Cambodia had been severely disrupted by the loss of the port of Sihanoukville early in 1970 and the RVNAF/US crossborder operations in May-June 1970. This required the enemy to increase his logistic resupply efforts on his one remaining infiltration route to Cambodia and Southern RVN , the Ho Chi Minh trail through Laos . _2/

 

*  Commando Hunt I was the name for the dry season campaign of November 1968 through April 1969. Commando Hunt III covered the period November 1969 through April 1970.

 

The Ho Chi Minh trail complex begins at four mountain passes along the North Vietnamese/Laotian border, Nape, Mu Gia, Ban Karai, and Ban Raving. _3/

In October 1970, the North Vietnamese started to move supplies into Laos across the Mu Gia and Ban Karai passes, _4/ but traffic south of the passes remained light due to heavy rain and two tropical cyclones, Kate on 25 October and Louise on 28 October. _5/  As the enemy road maintenance crews repaired the road system and the rivers subsided, truck movements increased on the Ho Chi Minh trail. During November there was an average of 252 Igloo White sensor-detected truck movements per day but most of the traffic was in northern Steel Tiger. On 27 November, a high of 889 sensor-detected truck movements was counted. The total number of sensor-detected truck movements for November was 7564. During December 1970, the number of sensor-detected truck movements increased to an average of 665 per day. The highest daily total for the month of December was 1037 and the overall total for the month was 20,601. _6/

When flooded the Xe Kong River acted as a barrier to the continued movement of the supplies down the Ho Chi Minh trail system. The Xe Kong had flooded in October and continued to carry an unusually high amount of water during November. Reliable reports indicated the North Vietnamese were storing large quantities of supplies to the north of the river, awaiting a time the Xe Kong could be forded.

Studies of sensor-detected truck movement patterns, climatic conditions, and North Vietnamese supply procedures led 7th Air Force Intelligence to suspect that there was a major storage complex in the Ban Bak area. Similar indications had been noted during previous dry seasons. Between 1 September 1970 and 18 December 1970 , 25 items of intelligence relating to targets in the Ban Bak area were received. Two pertained to points within one kilometer of the storage area eventually uncovered at Universal Transverse Mercator Map (See Figure 2) coordinates XC855540. One was a reconnaissance photo showing bunkers and a large open area containing supplies on 4 September 1970 . The other was a 20 November 1970 report from a forward air controller of antiaircraft artillery fire and supplies on the side of the road. There were-forward air controller (FAC) and photo reconnaissance reports of truck revetments, supplies, possible truck parks and storage areas located from one to - seven kilometers away from the storage area with the majority being from two to five kilometers to the north. During November 1970, Igloo White sensors detected almost four times as many truck movements into the Ban Bak^* area from the north as departed it moving south. 7/  Intelligence signs indicated a major supply dump and storage area near Ban Bak and north of the Xe Kong River existed; the next task was to find it (See Figures 3 and 4).

* The village of Ban Bak was 2.8 nautical miles east of the truck park/ storage area and 85 nautical miles west of Da Nang Air Base, Republic of Vietnam .

CHAPTER II

MORNING, 19 DECEMBER 1970

Shortly after midnight on 19 December 1970 , an 0-2 Covey^* Forward Air Controller (FAC) from the 20th Tactical Air Support Squadron (20TASS), Da Nang Air Base (AB), crossed the mountain range that paralleled the border separating Laos and South Vietnam . The pilot of the aircraft was First Lieutenant John R. Browning, who in a few days would complete his 100th FAC mission over Laos , and the navigator was Captain Norman J. Monnig. Both men were experienced in night FAC missions. Lieutenant Browning's call sign was Covey 281 and Captain Monnig, as navigator, was Covey Zulu._8/  (See Figure 5){The original CHECO report included a picture of the FACs; the quality of my copy isn’t worth posting.}

 

* The name Covey was given to the unit as a radio call sign and held no particular significance

 

At approximately 0100, the 0-2 passed over the ford where Route 924 crossed the Xe Kong River. On the night before, Captain Monnig had sighted and directed a strike against a ferry operating near the ford. On the19th, there was no activity in the ford. _9/

The water level in the river had not dropped enough to allow trucks to cross by fording. The Covey FACs suspected that the river continued to act as a barrier complicating the movement of supplies further south by truck. Almost every night, Covey FACs counted 20 to 30 trucks moving south down the Ho Chi Minh trail through the "White Cliffs," a ridge area which served as an ideal land mark and interdiction point for air strikes. South of the White Cliffs the trucks seemed to disappear into a triple canopy jungle plateau. Between the triple canopy jungle and the Xe Kong River was a mile of road crossing a number of exposed ridge lines dropping from the plateau to the river. The number of trucks observed per night moving from the plateau to the river was 10 or less. _10/  Signs pointed toward a supply area and truck park between the White Cliffs and the Xe Kong River somewhere in the triple-canopy jungle plateau.

Picture of 1/Lt Browning and Captain Monnig Removed for lack of detail in the copies.

After surveying the ford on the Xe Kong River, Lieutenant Browning and Captain Monnig moved north following Route 924. Route 924 was one of the main roads in the Ho Chi Minh trail complex. It was dirt, approximately 20 feet wide and in excellent condition. Trucks could be driven at estimated speeds up to 25 miles per hour along the route and the truck drivers according to the FACs, had become "brazen" regarding the observations of the FACs. Large labor crews maintained the road and road cuts were repaired in a day. _11/

Captain Monnig sighted nothing between the Xe Kong River and the triple canopy jungle area. Upon leaving the triple canopy jungle area, Captain Monnig sighted nine to 12 trucks moving south down Route 924. It was difficult to determine the exact number of trucks because not all trucks had their lights on. _12/

The night was clear with a bright moon at 30 degrees above the horizon. The moon helped the FACs to find the trucks moving along the trail, but the angle of the moon acted as a detriment. The truck drivers could drive with a minimum of artificial light using the brightness of the moon to illuminate the road. The low angle of the moon also lengthened the shadows made by the tall trees along the side of the road, making it more difficult to locate parked trucks.

Captain Monnig notified the Airborne Battlefield Command and Control Center (ABCCC), code name Moonbeam, that he had a target and requested a strike. Moonbeam reported a flight of F-4 aircraft in the vicinity. _13/

Captain Monnig continued to track the trucks with a Model NVSF-040 Uniscope. The Uniscope had entered 20TASS supply about three weeks earlier supplementing the Starlight scope. The Starlight scope had the capability to amplify light 400,000 times. The new Uniscope amplified light about one million times._14/

The area where the Covey FACs worked was a high-threat area. On the plateau, the AAA fire was intense and the triangulation extremely accurate. Some hits were reported but there were no casualties and no downed aircraft. _15/

But before the F-4 aircraft could arrive, the trucks entered the triple canopy jungle plateau area and pulled east off the road into some trees. Captain Monnig raised the amplification of the Uniscope to full volume and instructed Lieutenant Browning to hold the aircraft steady and to disregard any AAA fire. The trucks continued through the jungle and all that Captain Monnig could pick out in the Uniscope were flickers of light as the truck headlights reflected off the foliage. Then the trucks turned  north moving to an area 700 meters east of Route 924. _16/

Then the trucks stopped, doused their lights, turned them on again, then doused them again. About this time two F-4 aircraft, Wolfpack 93 from the 8th Tactical Fighter Wing, Ubon Airfield , Thailand , were in position. Covey fired a smoke rocket to mark the target. The fighters were armed with Mark 82 hard bombs and CBU 24 cluster bombs. _17/  On the first pass there were no secondaries. Captain Monnig moved the fighters 100 meters to the southeast. On the second pass, a 23 millimeter (mm) AAA gun started to fire. On the third pass, "the sky seemed to open up." A huge orange ball of fire with black smoke climbed a thousand feet into the sky. _18/

Bomb damage assessment (BDA) for the strike was reported as four trucks destroyed and two probably destroyed. In addition, there were reported eight small, nine medium, and 11 large secondary explosions; four medium sustained fires (the trucks burning), and three extremely large sustained fires that were bright orange in color with flames rising 150 to 200 feet in the air accompanied by thick black smoke. One extremely large secondary explosion resulted from a fire and appeared to be petroleum, oil and lubricants (POL). The other explosions appeared to be ammunition and more POL storage. The secondary explosions continued for one hour while Lieutenant Browning and Captain Monnig orbited the target area. _19/

As the secondary explosions and fires continued, Lieutenant Browning contacted ABCCC, "Moonbeam, you're not going to believe this but you have never seen anything like this before."_ 20/

Moonbeam replied, "We believe you, Covey, and you are right. In fact we are directly above you right now watching the show." _21/

Three extremely large sustained fires and the four trucks continued to burn when Covey 281 and Zulu left the area and passed visual reconnaissance of the target to Covey 237 and Juliette. _22/

The area was hit again at 0400, but it was during the following day; after-the bombs had removed the triple canopy jungle, that the majority of secondary explosions and fires started. _23/

 

CHAPTER III

19 DECEMBER 1970

The first Covey FAC into the area during daylight was Major Donald N. Conn (See Figure 6) flying alone in an OV-10, and using binoculars instead of a scope. One of his first tasks was to confirm the previous night truck toll, extent of the road cuts, and bomb damage assessment (BDA). _24/

He confirmed two destroyed trucks and indicated that the long sought truck park, fuel, and ammunition storage area had been found.

"Everything seemed to fit," Major Conn said. "There was a stream for water, the topography was level enough so that trucks could navigate it with ease, and the triple canopy of vegetation hid activities." He also saw evidence of bamboo trellis work over the roads and trails. Where the trees had been knocked away by the previous night air strikes, he could see POL barrels and vehicular tracks. He noticed a ravine that ran off Route 924 into the truck park/storage area and saw evidence that the ravine must have been covered with a bamboo trellis in addition to the triple canopy of jungle. The triple canopy of jungle and the bamboo trellis apparently made the truck drivers confident that their movements would not be discernible to the FACs. _25/ (See Figure 7)

Another indication that the area was important to the North Vietnamese was the presence of intense AAA fire. From the time the AAA opened upon Wolfpack 93 until it stopped 36 hours later, the AAA batteries fired at any airborne target. Two 23mm AAA guns were on top of a hill at XC8556, two 23mm AAA guns were by the side of the road entering the "Bomb Dump,"* one 37mm AAA gun was firing from the vicinity of the "Bomb Dump," and numerous small arms fired in and around the dump. Tracers were not used by the AAA gunners. 26/                         

 

* Name given to area by 20TASS.

 

Major Conn could see trucks moving and ground activity indicating that the North Vietnamese were attempting to move supplies from the area. He notified the day ABCCC, Hillsboro , that the target continued to be lucrative and requested additional strikes. _27/

Two.F-4s, Wolfpack 21, answered Major Conn's request and struck his white phosphorus smoke mark. The aircraft were armed with Mark 82 fuze-extended bombs and CBU 24s. The first strike was a probe strike. In a probe strike, ordnance was placed off to one side of the target to explore the possibility of additional targets. By directing ordnance delivery in a probing pattern, a FAC could reconnoiter an area by observing the location of secondary fires and explosions emitted from supplies that might be otherwise covered from visual reconnaissance. In the "Bomb Dump," the area was continually expanded by the probing method until the size of it exceeded an area 1000 meters wide by 1500_.meters long.

 (See Figures 8, 9, 10, 11.)   {These diagrams aren’t included in this excerpt.}

Additional strikes were called. Aircraft from the 8th Tactical Fighter Wing, Ubon AB , Thailand , 366th Tactical Fighter Wing, Da Nang AB , South Vietnam , 35th Tactical Fighter Wing, Phan Rang AB, South Vietnam , 388th Tactical Fighter Wing, Korat AB , Thailand , and Carrier Task Force #77 pounded the area. _29/

After completing strikes on other targets aircraft would arrive at the "Bomb Dump" to fire the rest of their ordnance, usually 20mm, into the bunkers and exposed supplies. Then the aircraft would hold above the "Bomb Dump" to watch the secondary explosions and fires. _30/

"I couldn't believe it", said First Lieutenant Robert Hansen, of the 421 Tactical Fighter Squadron, 366th Tactical Fighter Wing. "Every area we hit caused fires and explosions. The stuff would blow sky high. Then as we were hurting them the AAA gunners would open up. We had about three 23mm guns firing at us, but they weren't too accurate. So we concentrated on storage areas and hurting them that way, because if we got their ammo they wouldn't have anything to shoot at us." _31/

Captain James H. Houck, Jr., of the same unit continued, "Everything we'd hit, the stuff would just blow up. The FAC told us that one went up about 3,000 feet -- just sky high -- blowing gasoline cans and boxes about 1500 to 2000 feet and then blowing up in the air." _32/

The view resembled a large Fourth of July spectacular. Fire balls rose 2000 feet in the air. Ammunition rounds exploded at 9000 feet. There were red, orange and white fires from ammunition, POL and hard ordnance, respectively. The ravine where the trucks left the road to move into the storage area became a river of fire for a time as burning POL ran down it. _33/

There was so much debris flying in the air that the FACs worked in pairs; a practice called 'capping'. One FAC would hold near the target and direct strikes while the other FAC would stand off to the side and read AAA. To avoid the AAA fire, the pilot dipped, dove, climbed, and circled his aircraft. If a FAC suspected that he had been hit or flew through a heavy concentration of flak, the second FAC would make a visual survey of the aircraft for damage._34/

After 36 hours, the AAA began to lessen and then stopped all together _35/

The air strikes continued throughout the day. As one aircraft completed its strike and cleared the area, another aircraft was preparing to begin its strike. Fire and smoke could be seen 20 miles away._36/  Bunkers exploded. One F-4 strike hit a bunker right in the entry way. A large fire ball erupted out of the bunker rising to an altitude of about 300 feet out of which came two 50 gallon POL barrels that exploded approximately 350 feet further in the air._37/ On the ground, trucks were trying to move out of the area. A FAC fired a smoke rocket to mark a truck for a fighter, and hit the truck in the windshield destroying the truck before the fighter could complete the strike. _38/

For 19 December, reconnaissance photos revealed 14 trucks destroyed. There were 1,277 secondary explosions and 64 secondary fires._39/  A total of 41 sorties struck the target, 19 F-4s, 18 F-100s, 2 A-7s, and 2 B-57s. 40/   (See Figures 12 and 13).

Picture removed that wasn't detailed in the copying.

CHAPTER IV

 AFTERMATH

After 19 December 1970 , the operation continued to be one of destroying the supplies and hampering enemy recovery efforts. _41/  On 20 December, secondary explosions and fires numbered 3,318 and 53, respectively. _42/   Twenty F-4 aircraft and four F-100 aircraft struck the target. _43/         On 21 December, 25 sorties were flown against the target, _44/ but the BDA dropped to 174 secondary explosions and 40 secondary fires. _45/

Sorties were flown against the complex from 22 December to 25 December in a decreasing number each day, _46/  then on 26 December, another large number of secondary explosions and fires (2,520 and 33, respectively) was observed._47/  On that date a new high in sorties was flown against the target: 27 F-4s, 6 F-100s, and 10 A-7s, for a total of 43._48/  Twenty-eight sorties, including three B-52s, struck the target on 27 December, with 326 secondary explosions and 16 secondary fires. _49/ On 2 January 1971, 43 strike sorties were flown against the "Bomb Dump" resulting in_. 2273 secondary explosions, most of which were attributed to hitting a cache of artillery shells._50/      (See Figures 12 and 13).

Even with all of the strikes, enemy truck drivers continued to use the truck park and storage area. By 5 January 1971 , it was estimated that there had been 10,097 secondary explosions, 435 secondary fires, 43 trucks destroyed, and 11 damaged. _51/

Even using established standards for measuring BDA, the actual amount of supplies destroyed in the dump was difficult to determine. Estimates were obtained by counting the number of secondary explosions, fires, destroyed and damaged trucks and POL barrels. When a large number of secondary explosions occurred, the aircrews estimated the number of explosions per minute and multiplied by the number of minutes the explosions continued. FACs and fighter pilots timed the explosions on their wristwatches. To correct for duplication, Headquarters Seventh Air Force compared times and coordinates submitted by the units and adjusted final BDA estimates. Secondary fires varied in size very large, large, medium, and small; but for evaluation purposes all fires, size notwithstanding, were grouped together. The method used to estimate supplies destroyed in secondary explosions was to multiply the number of explosions times 1,000 pounds for the total number of pounds of supplies destroyed.

 

SECONDARY EXPLOSIONS, FIRES, AND TRUCKS DESTROYED AND DAMAGED

DATE                        Sec. Explosion              Sec. Fires Trucks Destroyed Trucks Damaged

19 Dec 70                            1,277                        64                  14                             3

20                                        3,318                        53                  17                             -

21                                           174                        40                  -                                -

22                                             19                           1                  -                                -

23                                             17                           7                  -                                -

24                                             10                        17                  -                                1

25                                               1                        19                  6                               2

26                                        2,520                         33                  3                               3

27                                           326                        16                  -                                2

28                                               6                        12                  1                               -

29                                               2                           5                  -                                -

30                                             14                           6                  -                                -

31                                               -                           1                  1                               -

1 Jan 71                                       -                         -                    -                                -

2                                          2,273                       141                  1                               -

3                                               15                        13                  -                                4

5                                             125                           7                  -                                -

TOTAL                             10,097                       435                  43                             15

SOURCE: Special Computer Listing of BDA, 7AF Int, XC 8440, 19 Dec 70 to 5 Jan 71 . SECRET/NF DOC 4.

FIGURE 13