Page Contents:

• Propst Research
• Marine Helicopter Transport Squadron 161 - Operation Mousetrap 1952
  • Mission
  • Purpose
  • Planning Phase
  • Execution Phase (No 1)
  • Execution Phase (No 2)
  • Discussion
  • Conclusions
  • Recommendations
  • Operation Mousetrap Statistics

Back to Page Contents

Propst Research

[KWE Note: The following article was written by Major Rodney R. Propst, USMC.  It was copied to the KWE from the USMC Combat Helicopter Association website at
http://www.popasmoke.com/korea/chronology.html with the permission of Wally Beddoe.]

In August of 1945 the world entered the Atomic Age at Hiroshima, Japan. The atomic bomb created a new era in warfare and as a result of it the Marine Corps began to concentrate on ways to increase dispersion and reduce vulnerability to this new and very lethal weapon. In the years immediately following World War II, the Marine Corps pioneered and developed a new concept in the mobility of assault troops and logistical re-supply with the advent of the helicopter. Vertical envelopment was conceived at the Marine Corps base in Quantico and proven during the Korean War.

In 1946, Lieutenant General Roy S. Geiger, Commanding General, Fleet Marine Forces, Pacific viewed the atomic tests at Bikini Lagoon. General Geiger felt strongly that atomic weapons would impact on how the Marine Corps conducted amphibious operations. In a letter dated 21 August, 1946 that General Geiger sent to the Commandant he stated, "It is quite evident that a small number of atomic bombs could destroy an expeditionary force as now organized, embarked, and landed..." [General Geiger urged the Commandant to] "consider this a very serious and urgent matter" [and that the Marine Corps] "use its most competent officers in finding a solution to develop the technique of conducting amphibious operations in the Atomic Age."

The Commandant, General Alexander A. Vandegrift, acted by referring General Geiger's letter to a special board of General officers with instructions to "...propose, after thorough research and deliberation, the broad concepts and principles which the Marine Corps should follow, and the major steps which it should take, to wage successful amphibious warfare at some future date..."

On 16 December, 1946 the special board submitted an advanced report to the Commandant recommending that parallel programs be initiated to develop a transport seaplane and a transport helicopter. The board further recommended that an experimental Marine helicopter squadron be organized to train pilots and mechanics and that the Marine Corps Schools develop a tentative doctrine for helicopter employment.  General Vandegrift concurred with the special board's results and began the actions to make Marine helicopters a reality. General Vandegrift visualized the Vertical Assault Concept as:

"With a relatively unlimited choice of landing areas, troops can be landed in combat formations and under full control of the flanks or rear of a hostile position. The helicopter's speed makes transport dispersion at sea a matter of no disadvantage and introduces a time-space factor that will avoid presenting at any one time a remunerative atomic target. It should also be noted that transport helicopters offer a means for rapid evacuation of casualties, for the movement of supplies directly from ship to dump and for subsequent movement of troops and supplies in continuing operations ashore."

The Commandant's goal for 1947 was to organize one developmental helicopter squadron with 12 helicopters in order to study helicopter employment in amphibious operations.

On 10 March, 1947 the Marine Corps Schools' Committee of the Academic Board headed by Colonel Robert E. Hogaboom submitted its report on "Military Requirements of Helicopter for Ship-to-Shore Movement of Troops and Cargo". The report stated: "... it is more realistic to approach the problem in increments, establishing initially the characteristics for a purely assault conveyance. . . "

The Mogaboom report went on to list the specifications for the assault helicopter as:

1. 5,000 pound payload
2. 200 to 300 nautical mile range (500 miles with an auxiliary fuel tank)
3. 100 knot cruising speed
4. 4,000' hover ceiling
5. external hook and hoist
6. self-sealing fuel tanks
7. overall dimensions to be able to fit on the hangar deck and elevators of the aircraft carrier.

On 1 December, 1947, in compliance with the Commandant's goal, Marine Helicopter Squadron One (HMX-1) was commissioned at MCAS Quantico, Virginia. Colonel Edward C. Dyer, who had been instrumental in establishing the Marine helicopter program, was the Commanding Officer. HQMC established the mission for HMX-1 as:

1. Develop techniques and tactics in connection with the movement of assault troops in amphibious operations, and
2. Evaluate a small helicopter as a replacement for the present OY aircraft.

On that first day of December 1947 Colonel Dyer was the sole member of HMX-1 and the squadron would not receive any aircraft until 9 February, 1948 when two Sikorsky HO3S-1's would arrive. At the request of Lieutenant Colonel Victor H. Krulak, the Assistant Director of the Senior School of the Marine Corps Schools, HMX-1 participated in Operation Packard II during May of 1948. This operation was an amphibious command post exercise developed and planned by the Marine Corps Schools. The operational plan was prepared by the student staff and provided for an element of the landing force, the staff of a regimental combat team (RLT), and HMX-1 to be embarked on escort aircraft carriers. Utilizing 5 HO3S-1s, HMX-1 flew a total of 35 flights carrying 66 Marines and a considerable amount of communications gear ashore from the ship. Operation Packard II provided the framework that proved helicopters could play an integral part in amphibious operations.

The Marine Corps Schools, by November 1948, had developed the world's first manual entitled Amphibious Operations--Employment of Helicopters (Tentative). This book was numbered 31 in a series of publications on amphibious operations.9 Phib-31 detailed many of the advantages of the helicopter and vertical assault, but more importantly it projected the concept of vertical envelopment well into the future, far outreaching the current capabilities of the helicopters the Marines were flying in 1948. Lieutenant Colonel Krulak describes the approach that the Marine Corps Schools used in preparing Phib-31, "...a prospective military philosophy. It consists of thinking in terms of the next war instead of the last.  This means starting with ideas, when you have nothing more tangible, and developing them into the concepts, procedures and weapons of the future."

Although, the Marine Corps was the last American military service to have helicopters, it became the first to institute a long-range program of working out helicopter combat techniques. (Phib-31 was copied by the U.S. Army, almost word for word, in its first helicopter manual.)

The months between 1948 and August of 1950 saw HMX-1 and the Marine Corps Schools continue to work on both the concept of vertical envelopment and the machines used to fly it. There were more Packard Operations, new helicopters like the HRP-1 and HTL-3, continued test and evaluation, and a Marine Air Ground Task Force demonstration for President Harry S. Truman and the members of Congress.

On 25 June, 1950, eight divisions of the North Korean People's Army (NKPA), crossed the 38th Parallel brushing aside patrols of the army of the Republic of Korea (ROK) and rapidly moved south in order to unify the Korean peninsula into a Communist state. In response to the Republic of Korea's request, on 28 June 1950, the United Nations ordered military sanctions against the North Korean invaders and by 7 July the U.S. Marines were ordered to activate a Regimental Combat Team. The 1st Provisional Marine Brigade was activated under the command of Brigadier General Edward A. Craig and was built around the 5th Marine Regiment and the 33rd Marine Air Group (MAG-33) of the 1st Marine Air Wing. 6,534 officers and men prepared to go to Korea.

HMX-1 was ordered, on the 7th of July, to send 8 officers and 30 men to the 1st Provisional Brigade for assignment to Marine Observation Squadron 6 (VMO-6) of MAG-33. These Marines would fly and maintain four HO3S-1 helicopters and would be the first helicopter unit organized for combat.  14 July, 1950 saw VMO-6, commanded by Major Vincent J. Gottschalk, embarked on the USS Badoeng Strait (CVE-116) bound for Korea. After only 31 months of evaluation for both the concept of helicopter employment and the aircraft themselves the Marines were on their way to war for the first time with helicopters.

The 1st Provisional Marine Brigade landed at Pusan, Korea on 2 August, 1950. The next morning General Craig made a reconnaissance of the area in a HO3S-1. This flight began a new era in command and control. General Craig eventually came to call the helicopter the "emergency weapon" of the Brigade command and staff. The Brigade maneuvered rapidly with the intent of counterattacking and stopping North Korean penetrations. The helicopters of VMO-6 proved their worth.  General Craig said of them:

"Marine helicopters have proven invaluable. They have been used for every conceivable type of mission. The Brigade utilized them for liaison, reconnaissance, evacuation of wounded, rescue of Marine flyers downed in enemy territory, observation, messenger service, guard mail at sea, posting and supplying of out guards on dominating terrain features and re-supplying of small units by air.

General Joseph L. Stewart recalled the use of the helicopter when he was a Lieutenant Colonel and the G-3 of the 1st Provisional Brigade at Pusan, Korea:

"I was the G-3 of the brigade in Korea that employed the first helicopters in combat. It was really dramatic to observe those who hadn't seen a helicopter operate before, to see the reactions and expressions of those who saw for the first time how the helicopter could be of such great assistance to us in planning these fast moving, put-out-the-fire type of operations."

Major Gottschalk, the Commanding Officer of VMO-6, stated, with historical significance, that the helicopter brought back a personal element to command and control on the battlefield that had not been seen in modern times:

"Perhaps the most important use of the helicopter in the early months of the Korean War concerned command and control. The flexibility provided the Brigade Commander to control his forces, change direction of movement, give personal instructions to subordinate commanders, and observe the resultant battlefield movement in a dynamic fast moving situation provided a new dimension to tactical control of the battlefield in a difficult terrain setting."

Major Gottschalk said, speaking of medevac flights, that, "The availability of the helicopter to pick up wounded from units that were cut off some distance from the main body improved the morale of the men in the lines." [He added that rescue missions also] "helped the morale of the fighter pilots in support of the Marine brigade."

The night of August 8th found Captain Victor A. Armstrong flying the first night medevac by lifting a wounded regimental surgeon to safety. The HO3S proved to be a rugged aircraft that could continue to fly regardless of hard landings in rough terrain and taking enemy small-arms rounds. Lieutenant General Lemuel C. Shepherd Jr., Commanding General, FMFPac, after observing the helicopters operate in Korea, said, "Later in Korea I saw helicopters come in with a dozen bullet holes in their wings and bodies--unless they are hit in a vital part, they will continue to fly." During the month of August 1950, the helicopters of VMO-6 logged 580 flights and a total of 348 flight hours with their HO3S's.

General Craig was such an advocate of the use of helicopters he wrote the following regarding their use in Korea and in future conflicts:

"VMO-6 was flown to Pusan from Japan. These aircraft have been invaluable in reconnaissance and the helicopters are a Godsend in this type of terrain, not only for reconnaissance but for supporting of combat patrols in mountainous terrain; for supply of food, water, ammunition; but also for the evacuation of casualties. . By separate dispatch to you.. .a request has been made to bring out elements of the Helicopter Transport Squadron. It is believed that this innovation will meet with outstanding results in combat in this mountainous terrain for the landing of patrols on top of mountain ranges.. .The helicopters presently available have been invaluable beyond expression ...[However] I feel they will not be able to sustain all the demands."

In September, 1950 VMO-6 prepared for the amphibious assault at Inchon. The helicopters of VMO-6 would play no part in the landing because there were not enough of them to lift the assault troops. On 16 September, D+3, Captain Armstrong landed his HO3S at the newly captured Kimpo airfield with General Shepherd and Colonel Krulak as his passengers. VMO-6 relocated to the airfield at Kimpo and began flying a dawn-to-dusk schedule in support of the 1st Marine Division as it fought its way across the Han river and on to northwest approaches to Seoul.  Seoul was officially liberated on September 29, 195O and on 12 October the Marines of the 1st Marine Division were back-loaded on ships at Inchon to be moved to the other side of Korea for a new adventure.

After a non-contested landing at Wonsan, Korea the 1st Marine Division, in November of 1950, was so extended that it had units at Hagaru, some 50 miles from the division CP at Hungnam. Major General Oliver P. Smith, the Division Commander, realized that he had unusual command and staff problems. General Smith ordered that the Main Supply Route to the Chosin Reservoir be strengthened and that an airstrip be constructed at Hagaru. As a result of Chinese Communist Forces (CCF) attacks in late November the 1st Marine Division was divided into five self-contained perimeters. The helicopters of VMO-6 provided the only means of contact between these isolated groups.

The night of December 1st saw the Marines come out fighting their way from Yudam-ni to Hagaru, 14 miles that would take 59 hours to cross. On 6 December, 1950 the 1st Marine Division began its breakout attack from Hagaru to Koto-ri. By the evening of the 7th of December with the 7th Marines leading and the 5th Marines covering the division fought its way to Koto-ri. From there the division marched to Hamhung with the lead elements reaching the sea late on the 10th of December. Every day of the breakout from the Chosin Reservoir the aircraft of VMO-6 were on call. Although the altitude reduced payloads and the bitter cold added to the difficulties of upkeep and repair, the helicopters of VMO-6 saved lives by flying medevacs and bringing in medical supplies.  From October 28 to December 15 VMO-6 flew 1,544 flights for a total of 1,624.8 flight hours.

The 1st Marine Division was back-loaded from Hungnam, between 10 and 24 December, by the Navy ships of TF-9O. The division was taken back to Pusan, which had been the first assembly area of the Brigade. In five months the Marines had managed to fight all around the Korean peninsula.

The spring of 1951 saw VMO-6 continuing to support the 1st Marine Division as it had in 1950. General Shepherd again spoke of helicopters by saying, "Due to the rugged terrain it would have been most difficult to operate in Korea without helicopters. They were a Godsend to the Marines."

In the summer of 1951, as the first year of Korean operations drew to a close, Marine helicopters had flown every mission except the one that had been envisioned for them--vertical envelopment during an amphibious assault. The remedy for this lack was to be filled by Marine Transport Helicopter Squadron (HMR) 161. HMR-161 was commissioned 15 January, 1951 at MCAS El Toro, under the command of Lieutenant Colonel George W. Herring.

With 43 officers, 244 men and 15 Sikorsky HRS-1 helicopters HMR-161 sailed for Korea on 15 August, 1951. The HRS-1 was a transport helicopter capable of carrying five or six combat Marines. HMR-161 arrived at Pusan, Korea on 2 September, 1951 as the 1st Marine Division launched an attack in the Punchbowl area in eastern Korea. HMR-161 moved to the front and shared Field X-83, near Chondo-ni, with VMO-6. The observation pilots of VMO-6 briefed the transport pilots of HMR-161 on the flying conditions in Korea.

On 12 September, 1951 HMR-161 indoctrinated the Marines of the 1st Shore Party Battalion in the techniques of loading and giving landing instructions to the large transport helicopters. The next day, in preparation for Operation Windmill I, supplies were sorted into 800 pound loads. At 1550 that day seven HRS-1 helicopters lifted with supplies suspended below each aircraft to fly a seven mile route in order to re-supply the 2nd Battalion, 1st Marines. Upon landing each helicopter picked up battle casualties and the wounded Marines were admitted to a hospital facility only 30 minutes after being wounded.  Operation Windmill I consisted of 28 flights for a total of 14.1 flight hours. 18,848 pounds of cargo were lifted and 74 casualties were medevaced.

On 20 September, 1951 the first helicopter-borne landing of combat Marines took place in Operation Summit. Despite dense fog, HMR-161 lifted 224 fully equipped Marines to the objective--Hill 884. The HRS-1's also transported 17,772 pounds of cargo in support of Operation Summit. The entire operation consisted of 65 flights, 31.2 flight hours, and took a total of four hours overall.30 The official report of Operation Summit, read in part:

"These initial efforts have demonstrated strikingly the great contribution to tactical and logistical flexibility that the assault helicopter offers ...[The report went on to say that]...helicopter functions will be progressively enlarged as time passes, and that the aircraft type must be recognized as a requisite component of a balanced military force."

On 27 September HMR-161 conducted the first night troop lift of combat Marines in Operation Blackbird. The HRS-1's lifted 200 Marines of "E" Company, 2nd Battalion, 1st Marines to the Punchbowl, on a night with no moonlight, in two hours and ten minutes. Operation Blackbird was not an unqualified success but many lessons were learned. The official report stated, "...night troop lifts in mountainous terrain are feasible provided a daylight reconnaissance of the landing zone together with the avenues of approach and retirement can be effected. Present equipment indicates that under present conditions in Korea these night lifts should be limited to movements within friendly territory."  Operation Blackbird was the only large scale night lift of combat Marines in the Korean War.

11 October, 1951 saw HMR-161 make history and headlines again. Operation Bumblebee began that morning at 1000 when the lift of 3rd Battalion, 7th Marines and it equipment commenced. The statistics tell the story of Operation Bumblebee:

• Number of helicopters: 12
• Number of flights: 156
• Total flight time: 65.9 hours
• Over-all time: 5.5 hours
• Number of Marines lifted: 958
• Average weight per man: 240 lbs
• Total weight lifted: 229,920 lbs

HMR-161 continued to support the 1st Marine Division in operations like Bushbeater, Rabbit-Hunt, Switch, Farewell, and logistical support in Muletrain. As 1952 passed HMR-161 grew both tactically and in their ability to respond to the needs of those they supported.

On 23 February, 1953 the Marines of HMR-161 began Operation Haylift II. This operation proved that the helicopter was destined to have a unique place in logistical support of combat Marines. Over a four day period, an average of 12 HRS-1's, flew from dawn to dusk carrying a combined total of 31,589 pounds per hour. Each aircraft made 27 round trips of the 15-mile leg and carried 11 tons of supplies. It would have taken a large fleet of trucks to provide this type of support and it would have taken four times as long.  Again HMR-161 and the helicopters from VMO-6 continued to provide tactical and logistical support to the 1st Marine Division in 1953 until the armistice was signed on 27 July, 1953.

Helicopter pilots and aircrewmen suffered a total of nine operational deaths in Korea, proving that their machines were not overly vulnerable.

HMR-161, from the first landing in Korea to the Armistice in 1953, flew a total of 18,607 flights, 16,538 flight hours, lifted 60,046 people, and transported 7,554,336 pounds of cargo. The transport squadron also evacuated 2,748 casualties in its 23 months in Korea. VMO-6 flew out 7,067 casualties during its 35 months in combat.

As a newcomer to Marine aviation, the helicopter proved to be a valuable tactical weapon in Korea. It met and exceeded the expectations the pioneers of vertical envelopment had for it. The tactical technique of hit and run had proved most effective when used in major troop movements and not when used in small lifts. The concepts developed at Quantico, Virginia in the late `4Os by HMX-1 had stood the test of war and had been proven in Korea. Amphibious operations of the future would owe much of their success to the pilots and men of VMO-6 and HMR-161 who flew in Korea.

Back to Page Contents

Marine Helicopter Transport Squadron 161 - Operation Mousetrap 1952

- Under Construction -

Headquarters
Marine Helicopter Transport Squadron 161
10 February 1952

From:    Commanding Officer, Marine Helicopter Transport Squadron 161
To:       Commanding General, First Marine Division
Subj:     Operation Mousetrap

Back to Page Contents

Mission

To airlift two (2) companies of the 2nd Battalion, 5th Marines, from their Corps Reserve position at Camp Tripli (DT 298-205) to positions in rugged mountainous terrain seven (7) miles to the South-East (DT 374-133 and 386-139).

Back to Page Contents

Purpose

a. To expedite the movement of these troops to positions from which they could rapidly deploy and form a tactical pattern designed to contain and capture an estimated 200 to 300 guerrillas.

b. To determine the feasibility of employing helicopters in anti-guerrilla operations and to develop tactics and techniques for such employment.

Back to Page Contents

Planning Phase

a. At 0100, 14 January 1952, a telephone call was received from the S-4, 5th Marines, who had been cleared by the Chief of Staff, First Marine Division, to effect direct liaison with HMR-161, and establish plans necessary for the movement of one (1) Battalion plus one (1) Company from Camp Tripoli to certain designated rear areas.  The following agreements were reached:

1. That the operation would commence at 1030, 14 January 1952.

2. That approximately 1,180 troops would be airlifted from Camp Tripoli to DT 374-133 and DT 386-139.

3. That further liaison would be effected as soon as additional information became available and more complete plans formulated.

b. At 0730, 14 January 1952, liaison was again established between this squadron and the S-4, 5th Marines, and the following plan agreed upon:

1. That the number of troops to be airlifted would be reduced from the original 1,180 to approximately 500, since the distance from Camp Tripoli to the desired tactical location was relatively short and trucks could transport the remaining troops to within a few miles of their destination.

2. That two (2) loading sites and two (2) refueling sites would be established at Camp Tripoli by the 5th Marines; one (1) loading and one (1) refueling site would be outlined by red panels, and the other loading and refueling site would be outlined with yellow panels.

3. That the troops scheduled to be airlifted to DT 374-133 would load aboard the aircraft t the red loading site, and the troops scheduled to be airlifted to DT 386-139 would load aboard the aircraft at the yellow loading site.

4. That an aircraft would reconnoitre the landing zone and select the most suitable positions within it for landing sites.

5. That the improvement of these landing sites would be the responsibility of the Commanding Officer, Air Delivery Platoon.

6. That two (2) 800 gallon refuelers would be dispatched from X-83 to Camp Tripoli and that one (1) refueler would be assigned to each refueling site.

7. That nine (9) aircraft would be assigned for the operation.

8. That the normal payload for the aircraft would be five (5) combat equipped troops, or four (4) combat equipped troops plus equipment organic to the unit.  It was further decided that as gas was burned, an additional passenger or equipment would be added.

9. That an officer from the Squadron would be present in the loading zone during the operation.

10. That ground crews from the Squadron would be present in the loading zone during the operation.

11. That the FAC of the 2nd Battalion, 5th Marines, would provide communications at both the loading and landing zones on an assigned frequency of 142.02.  The call sign for the loading zone would be "Family 14", and the call sign for the landing zone would be "Wholesome 14".

12. That the operation would require approximately four (4) hours to complete.

c. After completing the above mentioned plans with the S-4, 5th Marines, the Commanding Officer, Air Delivery Platoon was contacted and the following decisions reached:

1. That four (4) members of the Air Delivery Platoon would be assigned to the aircraft making the reconnaissance of the landing zone.

2. That when two (2) landing sites were selected within the landing zone, two (2) members of the Platoon would be landed on each site to perform the following:
   (a) Effect improvements on the landing sites.
   (b) Mark the sites with the assigned panels.
   (c) Act as signalman for the aircraft during the operation.
   (d) Expedite the unloading of troops at the landing site.

3. That two (2) members of the Platoon would be assigned to each loading site at Camp Tripoli and that they would be passengers in the first two (2) aircraft departing from X-83 for Camp Tripoli at 1000.

4. That the duties of the men at the loading sites would be as follows:
   (a) Direct aircraft in the approach to the loading site.
   (b) Expedite the loading of troops.

d. Upon completion of plans with the Commanding Officer, Air Delivery Platoon, the following decisions were made within the Squadron:

1. That two (2) 800 gallon refuelers would be dispatched at 0900 from X-83 to Camp Tripoli.

2. That an engineering crew of 20 men plus maintenance equipment would be assigned to the aircraft departing from X-83 to Camp Tripoli.  The duties of this crew would be to effect minor repairs and to refuel the aircraft.

e. Pilots were briefed at 0915 on the following points:

1. That two (2) pilots would be assigned to each aircraft.

2. That approximately 500 troops were to be airlifted from two (2) loading sites at Camp Tripoli to two (2) landing sites, one (1) at DT 374-133 and the other at DT 386-139.

3. That one (1) loading site was designated red and that all troops loaded at this site would be transported to the red landing site (DT 374-133).

4. That the other loading site was designated yellow and that all troops loaded at this site would be transported to the yellow landing site (DT 386-139).

5. That aircraft would be refueled at Camp Tripoli and that the refueling sites were located approximately 100 yards in front of the loading sites.

6. That five (5) aircraft would be assigned to the red pattern and four (4) aircraft would be assigned to the yellow pattern.

7. That as gas was burned the pilot would signal to the Air Delivery man at the loading site to add an additional passenger or equipment.

8. That the maximum gross weight of the aircraft would be 6,900 pounds.

9. That the first aircraft in each pattern would refuel after completing two (2) round trips and the second aircraft in each pattern would refuel after completing three (3) round trips.  That the remaining aircraft would make as many trips as possible before refueling.

10. That 425 pounds (71 gallons) of fuel would be carried in the rear tanks.

11. That aircraft would return to the loading site for refueling with a minimum of 75 pounds of fuel.

12. That the first aircraft would take off from X-83 at 1000 and proceed to Camp Tripoli with four (4) Air Delivery personnel, a crew chief, and first mechanic.  This aircraft would check on last minute details at the loading site.

13. That the second aircraft would take off at 1015 and proceed to Camp Tripoli, land its passengers on the red loading site, pick up troops and proceed to the red landing site.

14. That the remaining aircraft committed to the operation would take off at one (1) minute intervals and proceed to Camp Tripoli, land their passengers, pick up troops at the assigned landing site and proceed to the corresponding landing site.

15. That the route of approach and retirement would be governed by the terrain; aircraft would fly on the left hand side of valleys and in the event of an autorotation, a right turn would be effected to the floor of the valley.

16. That the assigned frequency for the operation was 142.02, Channel red, and the call sign at the loading site would be "Family 14."  The call sign at the landing site would be "Wholesome 14."

17. That an Operations Duty Officer would be assigned to the loading site to coordinate th operation.

Back to Page Contents

Execution Phase (No. 1)

a. The operation commenced as scheduled and was routine in every respect except for the following:

1. One (1) aircraft was downed because of mechanical failure and another aircraft was dispatched to X-83 to obtain the necessary parts to effect the repair.  This aircraft was detained at X-83 due to mechanical difficulty of its own, but eventually returned to the loading zone with the needed parts.  Because of these mechanical difficulties the services of these two (2) aircraft were lost for a period of approximately two (2) hours.

2. As the operation reached its final stage, a request was made by the S-4, 5th Marines, to airlift an additional 86 men from Camp Tripoli to the following locations:
   (a) DT 365-164
   (b) DT 416-103
   (c) DT 385-106
   (d) DT 372-108

3. These troops were assigned to designated loading sites and as aircraft landed to pick them up, the pilots were given the coordinates of their destinations.

b. The lift was completed at 1540.

Back to Page Contents

Execution Phase (No. 2)

a. On 15 January, at the request of the S-3, 5th Marines, five (5) helicopters were flown to the 2nd Battalion, 5th Marines C.P. located at DT 380-130.  These aircraft were requested to support, in conjunction with the guerrilla mop-up operations, the troops airlifted to this area on the previous day.  Upon reporting at 0730 it was decided that two (2) aircraft would be sufficient to handle the utility assignments requested and three (3) aircraft were returned to X-83.  A relief system for the two (2) remaining aircraft was established whereby two (2) helicopters with crews reported to the C.P. at two (2) hour intervals throughout the day.

The two (2) aircraft that remained at the C.P. were employed by the Commanding Officer of the Battalion to reconnoitre his positions, to regain contact with elements that had no radio contact, to make supply runs between the battalion dump and the C.P., to evacuate casualties from the C.P. to Camp Tripoli, to pick-up prisoners taken in the guerrilla operation and to return them from the Company C.P.'s to the Battalion C.P., carry prisoners from the Battalion C.P. to Camp Tripoli, and to lift certain critically needed equipment from the Battalion C.P. to positions on the line.  In most cases it was not possible to land the helicopters when supplying units on the line because the ridge positions occupied by troops were too uneven and were generally too densely forested to permit landings.  Supplies were lowered by rope while the helicopters hovered over troops positions.  In most instances this involved hovering out of ground effect at an altitude of 3,000 to 4,000 feet and was only made possible by the fact that there was a wind of approximately 20 knots.

The following day at 1130 an airlift was commenced to return the entire Battalion to Camp Tripoli.  Two (2) loading sites were selected and marked by panels in the vicinity of DT 408-137 and two (2) landing sites that had been used for the previous day's operation were established at Camp Tripoli.  After all personnel had been lifted from these sites, aircraft were diverted by the FAC to two (2) loading sites at the Battalion C.P. where the remaining troops were located.  The operation continued until 1700 and approximately 442 troops were returned to Camp Tripoli.  The operation was commenced again at 0730 on 17 January lifting the remaining troops from the Battalion C.P. to Camp Tripoli and was completed at 1230.

Back to Page Contents

Discussion

a. A unique aspect of this operation was the unusually brief planning stage.  The first word of the operation was received at 0100, 14 January 1952, and take-off time was established at 1000 the same day, therefore, most of the liaison between the 5th Marines and this squadron was accomplished over the telephone.  It was not possible to establish the close personal liaison essential for finely polishing the plans of the operation and in addition there was a limited time available to select and prepare the sites where the troops were to be landed.  A thorough reconnaissance of the objective area could not be made and landing sites had to be chosen hastily.

b. Prior to the initial take off the time interval between aircraft in each traffic pattern was set at one minute; however, since the distance between the loading and landing zone was approximately seven (7) miles and only four (4) or five (5) aircraft were in each circle, it soon became apparent that the pilots could take adequate interval by visual means alone.  In addition, aircraft downed for refueling or mechanical adjustments made the time factor less important in maintaining a safe interval between aircraft.  At one time, for example, there might only be two (2) aircraft flying in the pattern between the yellow sites; therefore, in the interest of expediting the operation, aircraft were allowed to depart from the loading zone with little regard for interval.

c. Relatively congested conditions at the loading zone introduced an element of danger not heretofore encountered in this squadron's airlift operations.  It was necessary for the airlift to make most approaches and departures from the loading zone over tents and congested areas bordering the field.  Wires at both ends of the field, a 50-foot flag pole at one site, and at times several aircraft in various stages of approach and departure, required alert flying and extreme caution.

d. Three (3) spare pilots were flown from X-83 to Camp Tripoli when the operation began.  When aircraft were landed for refueling, one of the spare pilots would be assigned to replace one of the incoming pilots and the relieved pilot would then standby for re-assignment.  In this manner, pilots were rotated and given an opportunity to take a brief rest.

e. The troop landings made in the vicinity of DT 385-106 were interesting; these zones had not been previously reconnoitered and no prepared landing sites existed.  Two of the landing zones were located in such a position that little or no wind could be counted upon for additional lift and since the aircraft were operating at a gross weight of approximately 6,900 pounds at an altitude of 2,500 to 3,000 feet, sufficient forward speed had to be maintained to insure adequate lift until the aircraft was over the intended landing spot.  Landing conditions were further made difficult by the fact that the ground was snow covered which made obstacles difficult or impossible to detect.  Once committed to the landing, there was no alternate maneuver.

Back to Page Contents

Conclusions:

a. Operation Mousetrap illustrated that a relatively large number of troops can be moved by helicopter on very short notice.  Experiences gained from similar problems proved invaluable in this operation.  With a minimum of planning and briefing, necessitated by the lack of time, the entire operation was completed with only minor difficulties.

b. This operation demonstrated the desirability of refueling, either at the loading zone, or between the loading zone and the landing zone.  Much time was saved by the fact that it was unnecessary for aircraft to return to X-83 to refuel.

c. The employment of helicopters in anti-guerrilla operations is highly feasible.  However, plans for their use should be more closely integrated with the ground troops scheme of maneuver.

d. It is believed that following the airlift much of the utility work performed during the guerrilla operation could have been more economically and efficiently accomplished by the use of the HTL type helicopter.

e. The helicopters could have been more effectively utilized had ground personnel and particularly the FAC been more fully aware of the capabilities and limitations of the aircraft.

f. Special attention should be given to the thorough indoctrination of FAC's in transport helicopter operations.

g. FAC's should be utilized more extensively in the planning as well as the execution stage of all airlifts.  They should screen all requests for helicopters and assign each approved request a priority.

h. Communications with and identification of troop elements was not positive during this operation and some means of air-ground communications and identification must be established.  Colored panels could be used to mark company positions or the positions of separate patrols, colored smoke grenades could also be used for this purpose.  Mirrors could be issued to individuals for signaling purposes and a definite panel pattern or colored smoke combinations could be used to mark casualty pick-up sites.  Portable electric (bull horn) speakers could have been very useful in establishing one-way communications with the ground elements from the airborne helicopters.

i. Padded drop bags similar to those used by the 1st Air Delivery Platoon could have been utilized to drop critically needed supplies to units located in terrain unsuitable for landing or hovering.

j. Patrols and small troop elements should be airlifted and landed in mass.  On this operation, individual patrols at times experienced difficulty in assembling because the aircraft were dispatched in singularly and sometimes landed 200 to 300 meters apart.  Because of rough terrain and the additional handicap of fairly deep snow, the rapid organization of personnel essential in this type of operation was delayed.

k. Pre-designated supply points might be useful in the support of patrol operations and helicopters would be used to stockpile supplies  at them.  If this system is feasible from an infantry commander's viewpoint, locating and identifying patrols by helicopter would be simplified.

Back to Page Contents

Recommendations:

a. That the closest liaison possible exist between the ground unit and the helicopter squadron and the helicopter commander be informed of the ground troop commander's scheme of maneuver.

b. That the HTL type helicopter be more fully utilized in utility work and the transport type helicopter be employed only when the HTL is unable to perform this mission.

c. That all FAC's be thoroughly schooled in the capabilities and limitations of helicopters and that this program be conducted by HMR-161 and coordinated by the Division Air Office.

d. That a study be made of an air-ground communications system so that the helicopters can communicate with units down to the squad level.

e. That a suitable portable electric bull horn be manufactured and included in the T/E of all helicopter squadrons.

f. That patrols in an operation of this nature be equipped with colored panels and colored smoke grenades.

That patrols or small troop elements be airlifted and landed in mass.

[signed] K.B. McCutcheon

Back to Page Contents

Operation Mousetrap Statistics

14 January 1952

• Number of Flights = 122

• Number of Troops carried = 638

• First Aircraft Take-off = 1000

• Last Aircraft Landed = 1540

• Total Time to Complete the Operation = 5 hours 40 minutes

• Total Flight Time = 41.5 hours

• Total Fuel Consumed = 1,350 gallons

• Average Refueling Time = 7 minutes

• Number of Aircraft Participating

  • 9 = 2 hours 40 minutes

  • 8 = 45 minutes

  • 7 = 2 hours 15 minutes

16 January 1952

• Number of Flights = 85

• Number of Troops Carried = 442

• First aircraft Took-Off = 1145

• Last Aircraft Landed = 1715

• Total Time to Complete the Operation = 5 hours 30 minutes

• Total Flight Time = 32.3  hours

• Total Fuel Consumed = 1,400 gallons

• Average Refueling Time = 7 minutes

• Number of Aircraft Participating

  • 7 = 2 hours 40 minutes

  • 6 = 2 hours 50 minutes

17 January 1952

• Number of Flights = 101

• Number of Troops Carried = 511

• First Aircraft Took-Off = 0720

• Last Aircraft Landed = 1230

• Total Time to Complete the Operation = 5 hours 10 minutes

• Total Flight Time = 40.1 hours

• Total Fuel Consumed = 1,600 gallons

• Average Refueling Time = 7 minutes

• Number of Aircraft Participating

  • 10 = 2 hours 5 minutes

  • 9 = 3 hours 5 minutes