COMBAT LOAD REPORT
LCDR Demetri Economos USN Marine Corps Combat Development Command Materiel Requirements Division Quantico, Virginia
31 DEC 2003
1. Purpose. To provide Director, Materiel Requirements Division the current anthropometrical data for height and weight, the optimum combat load in assault, march, and existence scenarios (as a function of % body weight for the average Marine), and recommend a combat load weight and balance figure for future combat systems based on the optimum loads calculated for the USMC.
2. Background. Overloading causes fatigue, heat stress, injury, and performance degradation.
Figure 1. Estimated load weights carried on the march by various infantry units throughout history (modified from Knapik et. al., Ref #21).
a. The problem of overloading the infantryman with equipment can been seen throughout history (Figure 1). Although not indicated in figure 1, the armies of antiquity traveled with loads equivalent to modern day armies; however, they offset their loads utilizing auxiliary transport (carts, animals, porters) in order to maximize combat effectiveness. Despite modern technologies (aircraft, wheeled vehicles), the infantryman continues to carry ever-increasing loads. Identifying the correct load for the infantryman to carry is essential for optimum performance effectiveness and mission success.
b. SLA Marshall’s book “Soldier’s Load and the Mobility of a Nation” is the most often cited document regarding combat loading of the infantryman. The premise of his analysis combines average body weight of soldiers and the percentage of that mean weight for the optimum load to be carried by the soldier. At the time of his book (1950) he estimated the average soldier weighed 153.6 pounds and (from his analysis, moderate experimentation, and experience) concluded that 33% of the body weight of an average soldier could be carried optimally (equates to 50.7 pounds).
c. More scientific anthropometrical studies have been performed and indicate that military personnel have increased in size and weight since the time of Marshall’s book. The last known study of this type for the Marine Corps was the 1971 MCDEC (Marine Corps Development and Education Command) evaluation of components of the 1970 MARCES (Marine Combat Electronic System) Report (Project 30-69-07). In parts of its conclusions, it stated that the mean average body weight and height for the USMC as 158 pounds and 68.7 inches, respectively.
d. Up-to-date anthropometrical values become an important factor when contemplating the development of future combat systems where weight and occupancy volume become essential variables in the design and lift capabilities of these future systems. To that end, the MCCDC-MRD commissioned a study to:
(1) determine the current 50%-ile body weight and height the Marine Corps.
(2) review the current load scenario definitions for accuracy.
(3) recommend load weights for the load scenarios.
(4) recommend a combat load weight and balance figure for combat development.
3. Study Method.
a. Exhaustive literature review covering DoD publications, military standards, military doctrine publications, scientific research publications, and commercial periodicals on the issue of combat loading.
b. Collect height and weight data from the Marsh Center USMC Manpower database, Quantico, VA and crosscheck with PFT rosters from commands in Quantico, Virginia, and the School of Infantry-East Coast, Camp LeJeune, N.C.
c. Calculate the USMC mean average for height and weight.
d. Calculate the optimum load weight for the load scenarios.
e. Calculate load weight and balance figure.
4. Results. All literature reviewed arrived at the same conclusion: the infantryman is overloaded.
a. Current Army doctrinal publications FM 21-18 (Foot Marches) and FM 7-10 (Infantry Rifle Company) prescribe weights of 48 and 72 pounds for the fighting and approach march loads, respectively. In a scenario defined as Emergency Approach March Load, higher loads of up to 120 pounds are allowed in conditions where approach marches are through terrain impassable to vehicles, or ground/air transport are not available, or when the mission demands that soldiers be employed as porters (note: enemy contact should be avoided at the higher load). Although the rationale behind the numbers was not indicated, it can be assumed that either Army science or published military standards influenced the Army’s doctrine.
b. In order to identify the source of the Army’s numbers, the Department of Defense Design Criteria Standard: Human Engineering (MIL-STD-1472F) was reviewed. This standard establishes general human engineering criteria for design and development of military systems, equipment and facilities. It recommends no more than 30% of body weight for close combat, and no more than 45% for marching. Comparing the percentage of body weight recommended for the load scenarios versus the actual loads recommended by the Army leads to the conclusion that the Army based its loads from the MIL-STD and that it assumed an average soldier weight of 160 pounds (160 x 30% = 48; 160 x 45% = 72). The MIL-STD-1472F does not define a standard for the emergency approach march load scenario, but it can be calculated from the Army’s publication as 75% of the soldier’s body weight, assuming the 160 pound solider as the average.
c. The next question is how did the Army arrive to its conclusion that the average soldier weighs 160 pounds? Review of the Military Handbook: Anthropometry of U.S. Military Personnel (DOD-HDBK-743A) found a listing of every conceivable anthropometrical measurement for military personnel of which stature and body weights are included. Table 1 highlights the last known weight and height measurements for the military:
Table 1. Highlight of weight and height averages for the services (modified from the DOD-HDBK-743A).
(*) Note that the 1988 average soldier weighed 173 lbs yet in the Army’s FM 21-18 it assumes a 160 lbs weight. It is concluded that the pub actually reflects 1966 data but other sections of the pub have been updated as of 1990. (†) The MCDEC evaluation indicated 158 lbs for the USMC in 1971, but in actuality it derived its data from the same 1966 study that composed this section of the DOD-HDBK.
d. As can be seen in Table 1, there is a need to update the weight and height data for all the services. The current study updated the body weight and stature parameters for the Marine Corps by collecting data from the Marsh Center Manpower database and by cross-checking that data with a smaller sample from the local commands of Quantico, VA and the School of Infantry, Camp LeJeune, N.C. The results in Table 2 show the averages by gender and rank and the results from the cross-check.
Table 2. USMC Weight and Height Data.
e. With an objective of defining optimum loads for the USMC in the various scenarios, the current study evaluated the current load scenario definitions for the USMC. USMC definitions of assault load, approach march load, and existence load are defined in the Improved Load Bearing Equipment (ILBE) ORD:
(1) Assault Load - The assault load is the load needed during the actual conduct of the assault. It will include minimal equipment beyond water and ammunition. From the human factors perspective, the maximum assault load weight will be that weight at which an average infantry Marine will be able to conduct combat operations indefinitely with minimal degradation in combat effectiveness.
(2) Approach March Load - The approach march load is defined as that load necessary for the prosecution of combat operations for extended periods with access to daily re-supply. The approach march load is intended to provide the individual infantry Marine with the necessities of existence for an extended period of combat. From the perspective of human factors, the maximum weight of the approach march load will be such that the average infantry Marine will able to conduct a 20-mile hike during a time frame of eight hours with the reasonable expectation of maintaining 90% combat effectiveness.
(3) Existence Load - The existence load is defined as that load taken from the point of origin into the assembly area. The existence load, for planning purposes, will be intended to support the individual from their pack when immediate re-supply is impossible. From the perspective of human factors, the maximum weight of the existence load will be such that the average infantry Marine will be able to conduct limited movement within the confines of Naval shipping, embark and debark aircraft or amphibious craft, and limited marching from the landing zone into a secured area.
f. To obtain the correct load weights to be carried in the load scenarios mentioned in 4.e., the current study searched for the optimum percentage of body weight recommended for the various load scenarios. All the literature (pubs, standards, and scientific research) indicates 30% and 45% of body weight as optimums in the assault and approach march load scenarios. There was no defined % for existence load in the literature:
Table 3. Optimum load carriage percentages versus load scenarios.
5. Discussion and Conclusions. The object of the current study was to: update USMC anthropometrical measurements for weight and height and derive a 50%-ile (mean) weight and height from the measurements, review the current load scenario definitions for relevancy, determine the optimum weight the average Marine should carry for the various load scenarios, and recommend a load weight and balance for future lift assets. These objectives were accomplished by data collection, review of standards, discussions with military scientists, and data calculation. The conclusions drawn from the results of the study reflect:
a. The average weight of a Marine is 169.0 pounds (male only), and 130.3 pounds (female only).
b. The average height of a Marine is 69.6 inches (male only), and 64.5 inches (female only).
c. Careful review of the literature and contact with military scientists for determining the optimum percentage of body weight the infantryman should carry in the various load scenarios have resulted in the conclusion of 30% and 45% of body weight for the Assault Load and the Approach March Load.
d. The Marine Corps definition of Assault Load is current and accurately reflects the load scenario.
e. The Marine Corps definition of Approach March Load is current and accurately reflects the load scenario.
f. The US Army FM 21-18 (Foot Marches) doctrinal publication indicates an Emergency Approach March Load scenario for mission coverage over a 72-hour period where air/ground transport is not available. There is no Marine Corps definition for the Emergency Approach March Load. This is a potential deficiency. It is suggested that the Marine Corps consider adopting a modified version of the Army concept. The following definition for a Sustained March Load is offered as an intermediate between Approach March Load and Existence Load:
(1) Sustained March Load - that load which may be necessary to accomplish the mission, including items necessary to sustain or protect over a period of approximately 72 hrs when air and ground transport are not available. Larger packs must be carried and contact with the enemy should not be expected as the heavier packs could negatively affect combat effectiveness. From the human factors perspective, well-conditioned Marines can easily carry the Sustained March Load.
g. Assuming the addition of a Sustained March Load definition, it is suggested the Marine Corps modify the current definition of Existence Load to the following (modification is italicized and bolded):
(1) Existence Load - defined as that load taken from the point of origin into the assembly area. The existence load, for planning purposes, will be intended to support the individual from their pack when immediate re-supply is impossible. Due to the heavier loads carried, enemy contact should be avoided. From the perspective of human factors, the maximum weight of the existence load will be such that the average infantry Marine will be able to conduct limited movement within the confines of Naval shipping, embark and debark aircraft or amphibious craft, and limited marching from the landing zone into a secured area.
h. Careful review of the literature and contact with military scientists gave no indication that an optimum percentage of body weight had been defined for a Sustained March Load or an Existence Load. This is a deficiency. In lieu of concrete experimentation, it is suggested that the Marine Corps consider 60% and 75% as the optimum percentage of body weight for carriage in the Sustained March Load and Existence Load (respectively). These numbers are based on data extrapolation from Army load carriage experiments and derivative conclusions from the Army doctrinal publications.
i. Given the conclusions from 5a. – 5h. that the average Marine weighs 169 pounds and the optimum percentage of body weight for the loading scenarios are 35, 45, 60, and 75%, the following table is recommended for approval for combat loading in the in the defined loading scenarios:
Table 4. Optimum load weights for the load scenarios
j. Using the figures from the table above, the following is suggested as the representative load list in the defined scenarios as adopted and modified from the FEB 2003 ILBE ORD (numbers are derived from actual weight of gear projected to be carried by the Marine in those scenarios and are not necessarily prescriptive):
* Considered as part of the tear weight and not included in the weight of combat load.
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