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RSR and CSR: Why the Confusion?

Army personnel ordering ammunition sometimes confuse the required supply rate and controlled supply rate terms used in determining the amount of ammunition a unit will receive. The author explains how each is determined, how the rates are used, and how they affect the amount of ammunition a unit receives.

Both the concepts and the meanings of “required supply rate” (RSR) and “controlled supply rate” (CSR) continue to be misunderstood and misapplied in our Army—often by people who should know better. These concepts are worth understanding because their application is essential to success in many operating environments. The fundamentals are simple, the players are relatively few but critical, and the application is relatively straightforward.

First, let me put this discussion into context. This article is written primarily from an Army perspective, using Army doctrine and some nondoctrinal publications and tools. It also takes a brief look at the RSR-CSR issue from a joint perspective, addressing what joint doctrine says about it. Other service components have similar issues to deal with, and similar ways to cope with them. The Marine Corps generally employs the same process as the Army because they share basic ammunition distribution principles and train jointly, even if they use significantly different organizations and equipment to execute their missions. Because they use many common weapon systems, a class V (ammunition) supply problem for the Army is usually a problem for the Marine Corps as well. This supply challenge is particularly relevant in an operational- or strategic-level context.

What is RSR?

RSR indicates how much class V is needed for an operation. This is an expression of operational requirements—what the warfighter says he needs. It is a logistics issue, but it is an expression of warfighting requirements, not logistics capabilities. The S–3s and G–3s of the world should be vitally interested in RSR because it expresses what they believe they need to accomplish the mission. Field Manual (FM) 4–30.1, Munitions Distribution in the Theater of Operations, explains it as follows—

To sustain tactical operations for specific periods, units determine their munitions requirements and submit a RSR. The RSR is the amount of ammunition that a maneuver commander estimates will be needed to sustain tactical operations without ammunition expenditure restrictions over a specified time. The RSR is expressed as rounds per weapon (on-hand) per day, or as a bulk allotment per day or per mission. RSR computations and routing are performed by unit S3s/G3s. As such, it is not a logistics function, but the S4/G4 should assist in the process. RSRs can be computed using manual or automated procedures. Weapon density (WD) and mission are key to determining the RSR.

Who Computes the RSR?

So who usually computes the RSR for an organization? The logistician. This is probably the first step in a long process that causes RSR and CSR to be misunderstood and misapplied. Why does the logistician compute the RSR? Because he knows how. The logistician is the person with the tools and the information to do the initial computations and to consolidate the results as the information is passed up to higher levels of the organization.

Is this bad? Not necessarily. The logistician needs to understand logistics requirements, and RSR is clearly an expression of operational logistics requirements. However, the tactical operators and logisticians should have a truly common understanding in this area. Their points of view are different. The tactician must understand why he needs to express the needed ammunition in the RSR in order to accomplish his mission, and the logistician needs to understand how much the tactician needs in order to ensure that requirements do not exceed capabilities.

How is the RSR Computed?

How does the tactician estimate how much ammunition he needs? What does the logistician use to compute RSR? This can be accomplished in one of two ways: generate an estimate based on historical experience, or use an estimation tool.

An organization that has conducted a similar operation has a historical reference that can be an excellent resource. How much was needed for a similar operation last time? This figure can be used as a baseline and adjusted based on mission analysis.

When no recent similar experience is available for reference, some automated tools are available that can help. The Logistics Estimate Worksheet (LEW) and Operations Logistics (OPLOG) Planner are two that are often mentioned as possibilities. Each has strengths, weaknesses, and limitations. The class V workbook in the “Rates Portal” at https://www.cascom.army.mil/private/cdi/
can also be used.

An in-depth discussion of automated ammunition consumption planning tools is beyond the scope of this article and will be the subject of a future article. In the meantime, use caution when using automated planning tools; make sure to give the results a “common sense” test. LEW provides a good level of detail, but it is complex and fragile, requires significant operator skill, and is useful only up to about the battalion level. LEW is also an unofficial product—it is not supported by the Army. OPLOG Planner is supported by the Army, but it is not suitable for computing an RSR because it is primarily a transportation planning tool. OPLOG Planner does not provide sufficiently detailed information for accurate munitions consumption to identify a true RSR. The problem is that OPLOG Planner, at least in its current form, embeds the weight and cube requirements for the components of separate-loading ammunition (155-millimeter howitzer, for example) but does not list the components, such as propelling charges, fuses, and primers. It also does not compute requirements for ancillary ammunition items, such as grenades or pyrotechnics. If the answer does not make sense, cross-check the results.

At the tactical level, RSR is normally expressed in rounds per weapon per day or rounds per system per day. RSR is a bottom-up fed estimate; at each successively higher headquarters, the requirements are consolidated until they ultimately reach the theater level. This is probably the second step on the path of misunderstanding RSR and CSR. As the quantities of class V requirements are consolidated, “each” starts to disappear from the unit of issue column. Requirements are expressed in terms of short tons rather than individual rounds. It is a convenient and absolutely necessary shorthand for expressing quantities when individual numbers get too large. When ammunition quantities are expressed in terms of short tons, the figure generally includes packaging, which can be a significant contribution to the total weight and a real issue when calculating transportation requirements.

Ultimately, at either the Army force (ARFOR), joint task force (JTF) headquarters, or combatant command (COCOM) level, the RSR totals for an operation are consolidated. This consolidation is usually expressed as the number of short tons required per unit of time. High-value, low-density munitions, such as guided missiles, may be expressed in terms of individual rounds. The unit of time may be per day, per phase of the operation, or for the operation as a whole, which provides the macro look that is essential for planning.

A micro look, which is normally invisible to all but a few key people, is also required. That micro look is a close examination of every ammunition type individually. Totals may be expressed in short tons or as each (high-value, low-density munitions). Even when expressing the RSR in short tons, an understanding of the total number of rounds in each short ton is essential. For example, 1,000 short tons of linked .50-caliber ammunition sounds like a lot of ammunition. But is it enough to ensure that every system employed in the operation is supplied with enough ammunition to accomplish the mission? This question prompts a comparison of requirements and capabilities in terms of class V supply and distribution.

What is CSR?

If there is a shortfall in the ability to supply any ammunition type, that shortfall needs to be quantified and expressed in a way that is understood clearly and easily. That expression is the CSR. At its most basic level, CSR means, “this is what I can give you.” A CSR is expressed when the requirements (RSR) exceed the capability of the logistics system. CSR is driven by logistics constraints, but it is still an operational consideration. Here is why: the logistician says to the commander, “Sorry, sir, but this is all we have to work with, and it’s less than what your operational guys say they need.” It is up to the commander, advised by his staff, to determine how best to deal with the shortfall. CSR also communicates to subordinates, “Heads up, folks. We are not going to be able to give you everything you say you need. Here’s where we’re short.” CSR is a way of expressing command regulation of a critical supply item and defining how tightly regulated the item will be so subordinates can plan for the constraint.

FM 4–30.1 specifies who establishes a CSR and why as follows—

RSRs are developed by maneuver commanders and submitted to the next higher HQ [headquarters]. HQ at each level reviews, adjusts, and consolidates RSR information and forwards it through command channels. The ARFOR determines the CSR by comparing the total unrestricted ammunition requirements to the total ammunition assets on hand or due in. Several factors limit the amount of ammunition available for an operation (such as stockage or lift capabilities). Accordingly, ammunition issues are controlled by CSRs. The ARFOR establishes the CSR, which is based on the amount of munitions available for issue. When a munitions item is in short supply, the CSR is low. The commander determines who receives the ammunition.

Who Develops the CSR?

While RSR is a bottom-up expression of requirements, CSR is the commander’s top-down expression of what he is able to provide to subordinates and how he will distribute these assets. CSR may identify some hard and fast constraints, but it also allows the commander to provide weight to his designated main effort by providing different CSRs to main and supporting efforts. The expression of CSR is therefore part of the weighting of main and supporting efforts.

One would expect the main effort to receive more of everything, but that may not necessarily prove to be the wisest use of assets. It depends on an analysis of the mission and the risks of subordinates. For example, the logistics distribution system is not likely to be the main effort of an operation, but air defense units providing coverage for key logistics nodes may receive a higher CSR than those that are directly supporting maneuver units. Likewise, a key supporting effort, even a deception operation, might receive more of a specific ammunition type than the designated main effort if that type of ammunition is crucial to the success of the overall effort. For example, a supporting effort might use artillery-delivered smoke to mask its movement or strength in order to prolong the effectiveness of a deception operation.

How is CSR Computed?

CSR might be computed and expressed early in the planning phases, even before an RSR has been calculated. In what cases might this take place, and why would this action be important? When the availability of a particular type of ammunition is already a concern, early expression of constraints, including CSR, may be vitally important to subordinate planners. If the shortage is in Hellfire missiles, for example, during the development, comparison, and selection of courses of action (COAs), planners may want to think carefully about making AH–64 Apache helicopters their prime killer of enemy armor. Likewise, if 120-millimeter tank ammunition is constrained, COA development needs to include options that rely less heavily on M1A2 tanks as the primary enemy armor killer.

CSR normally applies to individual items of ammunition rather than to ammunition as a class of supply, so it is typically expressed in terms of rounds per weapon (or system) per day. CSR could be expressed in terms of short tons or applied to the entire class of supply, but it would not have much meaning, except at higher echelons. Theater ammunition requirements tend to be consolidated into manageable terms like short tons.

Early in an operation, especially in the theater opening phase, the ability to deliver ammunition may be constrained. Commanders must make difficult decisions to ensure that the logistics system concentrates on delivering the ammunition types that are most critical in the opening phases of an operation. Service component perspectives may differ here and create significant friction among the components of a joint force. For example, the air component commander is likely to put air-to-air missiles high on his list, while the land component commander is likely to place surface-to-air, air-to-surface, and surface-to-surface munitions first in his priorities. In this situation, it is up to the joint force commander to listen to the rationale of his service or functional component commanders and decide how transportation assets will be allocated to deliver munitions designed to meet the perceived threats.

This example of joint-level decisions also points toward an interesting match of Army and joint doctrine. As discussed previously, FM 4–30.1 states that the ARFOR commander establishes a CSR if one is needed. Interestingly, joint doctrine says almost exactly the same thing. A search of joint doctrine reveals that CSR is described only in the context of an Army component or a joint force land component. Joint Publication (JP) 3–31, Command and Control for Joint Land Operations, and JP 3–09, Joint Fire Support, both mention CSR, but only to describe where to place CSR information in an operation plan or operation order (OPORD). JP 4–09, Joint Doctrine for Global Distribution, discusses CSR, but only as an Army component commander issue. Joint doctrine apparently does not address a joint CSR, in which distribution of available ammunition is allocated among service or functional components. Such a case would be rare, but it could happen, and we must assume that it would be resolved by the joint force commander, based on input from his staff and component commanders.

Except in the very first days of an operation, ammunition is unlikely to be in short supply across the board. Specific types of ammunition are more likely to be in short supply. New items in the inventory are likely candidates; everyone wants the latest, greatest, longest-range ammunition available. New ammunition types with enhanced or special capabilities also are likely to be in high demand and short supply. Older ammunition types also may be the culprits, especially if a weapon system has been designated for phase out but has been pressed back into service.

The simplest, most effective way to state limitations in class V availability is to express the CSR in terms of rounds per weapon (or system) per day. When expressed in these terms, it is easy for anyone at any level to understand what the CSR means in terms of fighting the battle throughout all the phases of a campaign. Expression in short tons tends to limit comprehension of the true meaning of a CSR. Expression in rounds per weapon per day provides a much more meaningful and easily understood expression for the fires and maneuver folks who will actually plan and execute an operation. Any good logistician can use CSR numbers to compute what will actually be coming through the supply pipeline in order to plan for transportation and storage requirements.

Where Is CSR Found?

If you are reading an OPORD to find out if a CSR will affect you, where should you look? On the other hand, if you are writing an OPORD, where is the best place to put CSR information? The answers to these questions may be unclear because different sources of doctrine contain some inconsistent or conflicting information.

FM 5–0, Army Planning and Orders Production, does not help much. The only references to CSR, other than in the glossary, are brief references in two of the annexes. FM 4–0, Combat Service Support, describes CSR development but does not specify where it should be found in an OPORD. FM 4–30.1 provides some real guidance. It states, “The CSR is disseminated to units through the OPORD. The CSR should appear in the OPORD in paragraph 4, or in either the service support or fire support annex.”

Some, but not all, Army doctrinal publications say CSR information should be in the fire support and engineer annexes of the OPORD. However, all say CSR should be in Annex I, Service Support. Put CSR information there (Annex I), for sure. CSR information should be considered optional in the engineer and fire support annexes. If you are writing an OPORD that includes CSR information, put a reference to Annex I in paragraph 4 of the basic OPORD. Do the same in Annex D, Fire Support, and Annex F, Engineers. These references help simplify the crosswalk effort of OPORD review and analysis and prevent having to update multiple sections of the OPORD during its development if information changes. If a CSR is in effect, it always should be found in Annex I; this should be the one-stop, always-reliable answer for all information relating to CSR. For a joint order produced in the Joint Operations Planning and Execution System, the equivalent is Annex D, Service Support.

Why Are RSR and CSR Important?

RSR is an estimate of what will be required to accomplish a particular mission. As an estimate, it can be calculated at any level, but in its ideal form, it is a bottom-up estimate that is consolidated for commanders at each higher level of an organization, all the way to the joint force or theater level. CSR is an expression of what can or will be provided to subordinate units. Both RSR and CSR are operational issues—the commander’s business—even though the necessity of having to impose a CSR is driven by logistics constraints.

Commanders, advised by their staffs, are the decisionmakers who determine whether or not a CSR will be imposed and how it will be distributed to subordinates. CSR need not be a fixed number across a given level of command; different subordinates may be given different CSR values in order to weight main and supporting efforts. The imposition of a CSR may have a significant effect on COA development, analysis, and selection. The CSR may also be the factor that drives a need for an operational pause or a culmination point. If units expend ammunition at their RSR estimate rate when a CSR is in effect, they eventually will reach a zero-balance condition or be constrained to an expenditure rate that matches the CSR.

The basic concepts of RSR and CSR are simple, but their execution is complex. The complexity generally derives from the need to consolidate and aggregate RSR information as it goes up the chain and then de-aggregate CSR information and express it in terms that make sense at the user level as it goes back down the chain. It can be a challenge, especially when the conversion from short tons to rounds per weapon (or system) per day involves enormous numbers. Still, the process works. It is a crucial result of mission analysis and a key element of running estimates that are used to generate OPORDs.

Dr. Thomas E. Ward II is an assistant professor in the Department of Logistics and Resource Operations at the Army Command and General Staff College at Fort Leavenworth, Kansas. He holds a B.A. degree in political science from the University of Oklahoma, an M.B.A. degree from Florida Institute of Technology, and a Ph.D. degree in organization and management from Capella University.