Moving U.S. Forces: Options for Strategic Mobility Section 4 of 12
February 1997

Chapter Two

Strategic Airlift Forces

Transport aircraft can move a load of military equipment almost anywhere in the world at more than 400 nautical miles per hour. Because of their speed and the worldwide access they pro-vide, airlift planes are an important means by which the Department of Defense can project its forces.

But planes are also much more expensive than ships or prepositioned sets of equipment, particularly when the United States needs to move large forces. One way that DoD lowers the cost of airlift is by planning to use planes owned by the private sector in the event of war. In the past, DoD has also purchased some planes for its own fleet that are based on civil designs, which tend to be less costly to build than more specialized military aircraft.



The Current Strategic Airlift Fleet

Today's airlift fleet is made up of both planes that are dedicated solely to military missions and commercial aircraft that are part of the Civil Reserve Air Fleet (CRAF). If mobilized fully, the combined fleet would have a total theoretical airlift capacity of almost 50 million ton-miles per day (see Box 2 for a definition of the units of measure used in airlift analysis). Nearly two-thirds of that amount comes from the military's own planes, with the rest contributed by civil carriers (see Figure 2).


Figure 2.
Theoretical Capacity of the Strategic Airlift Fleet Under the Administration's Plan, 1996-2007

SOURCE: Congressional Budget Office based on Department of the Air Force, 1997 Air Mobility Master Plan (Scott Air Force Base, Ill.: Air Mobility Command, October 11, 1996).

NOTE: Theoretical capacity is based on standard planning factors of the Air Force's Air Mobility Command. Based on a 1995 study of mobility needs and later analysis, the Department of Defense set a requirement of 49.7 million ton-miles per day (MTM/D) for theoretical capacity. To reach that level, the Air Force plans to supplement military planes with Civil Reserve Air Fleet capacity, which would amount to 20.5 MTM/D or less over the 1996-2007 period.


 
 
Box 2.
 Basic Units of Measure and Terms in Airlift Analysis
Tons:  The amount of cargo that the Air Force moves by airlift is usually described in terms of its weight in short tons (2,000 pounds).  Because of their physical dimensions and shape, however, individual pieces of cargo may not fit on certain aircraft even if they meet the plane's weight limitations. 

Ton-miles:  A unit of measure that takes into account both the weight of cargo and the distance over which it must be carried.  For example, airlifting a 5-ton truck over the 3,500 miles from Dover, Delaware, to Germany would amount to a workload of 17,500 ton-miles.  Moving the same truck to Saudi Arabia would take about 32,500 ton-miles. 

Millions of ton-miles per day (MTM/D):  The standard unit of measure of theoretical airlift capacity.  One can think of 49 MTM/D (a recent Defense Department goal) as the ability to move 7,000 tons of cargo over 7,000 nautical miles in a day's time—roughly the equivalent of moving less than one light infantry brigade to the Persian Gulf in one day.  

Theoretical capacity:  A measure of what, in theory, all airlift planes could carry when fully mobilized.  Because theoretical capacity is calculated using average measures of each plane's performance, it does not reflect constraints that the Air Force might face when deploying to a specific conflict.  As a result, actual airlift deliveries tend to be lower than theoretical capacity.  At the start of Operation Desert Shield, for example, the theoretical capacity of U.S. military and Civil Reserve Air Fleet planes was 48 MTM/D.  However, some aircraft were withheld for other missions or suffered from maintenance problems; not all commercial planes in the Civil Reserve Air Fleet were called into service; and reserve aircrews were only partially mobilized.  In addition, at the start of airlift operations, the United States had access to a limited number of airfields in Saudi Arabia, some of which lacked trucks and other equipment to refuel planes quickly.  As a result, actual deliveries averaged only 11 MTM/D during the first month of operations, or 23 percent of theoretical capacity.  

Outsize cargo:  Cargo that is so large or bulky that it can fit on only two types of U.S. cargo planes—C-5s or C-17s.  Airlift planners categorize cargo as outsize, oversize, or bulk.  Oversize cargo is smaller than outsize and can fit on some military and commercial transports, whereas bulk cargo fits on a standard-size pallet and can be accommodated on all types of airlift planes. 

Maximum on the ground (MOG):  An average measure of the number of planes that a particular airfield can service at any given time.  MOG values can vary over time.  They reflect both the physical limitations of an airfield —such as ramp space, refueling capabilities, and availability of equipment to load and unload planes—and the competition for its use.

 
Department of Defense Aircraft

DoD's current fleet of strategic airlifters includes three types of cargo planes and two varieties of tanker aircraft (see Figure 3). Tankers are generally used to refuel other aircraft while in flight, but DoD needs fewer planes for that role today than it did during the Cold War because there is less call for long-range missions by strategic nuclear bombers. Thus, military officials plan to use some tankers for airlift missions.

Military cargo planes such as the C-141, C-5, and C-17 have special features that make them particularly well suited to moving military equipment. For example, they have wings that are high on the fuselage and ramps that are low to the ground so military personnel can move equipment on and off quickly. The C-5 and C-17 also have large doors and unobstructed cargo compartments that can carry the largest or most awkwardly shaped pieces of military equipment, such as tanks and helicopters. Military transports also have multiple sets of electrical and mechanical systems and other safety features so they can continue to operate even if damaged in battle.

By contrast, KC-10 and KC-135 tankers are modified versions of civil planes. Because of intense competition in the market for commercial airliners, civil transports are designed to carry loads of passengers, baggage, and cargo as cost-effectively as possible. With narrower cargo holds and smaller doors, civil transports are better suited for moving bulk cargo on standard-size pallets. On the down side, they require special elevators for loading and unloading since their cargo doors are higher off the ground. They also need longer runways than may be found in some parts of the world. But modern civil transports such as the Boeing 747 are very reliable and can carry larger payloads over a longer range without refueling than most types of military airlift planes. And because civil planes are pro-


Figure 3.
DoD's Strategic Airlift Planes

 
 
 The C-141 can carry an average payload of 23 tons. It is the primary plane the Air Force would use to air-drop personnel and supplies over long distances. First built in the 1960s, the average C-141 is nearly 30 years old. The Air Force plans to retire the planes from service by 2007.
 
 
 
 
 With an average load of 65 tons, the C-5 is the largest of DoD's military airlift planes. Unlike the C-141, the C-5 was built to carry the biggest pieces of military equipment (called outsize cargo), such as M1 tanks. It has doors and ramps at both nose and tail so cargo can be loaded more quickly.
 
 
The C-17 is DoD's newest transport plane. Like the C-5, it can carry outsize cargo. However, it is closer in length to the C-141, so its average payload is smaller than the Galaxy's--45 tons. DoD says the C-17's size and maneuverability on the ground give it an advantage over larger planes when airfields are congested.
 
 
The KC-10 is a military version of the McDonnell Douglas DC-10 and can carry an average payload of 40 tons. Although the KC-10 was designed as a tanker, DoD plans to use 37 of them to carry standard-size pallets of cargo in the event of a conflict. As with all civil-style planes, the KC-10 needs special equipment to load and unload its freight.
 
 
The KC-135 is a military version of the Boeing 707 that is used to refuel aircraft while in flight. DoD modified a small number of KC-135s to carry an average of about 10 tons of cargo apiece. In the event of a conflict, DoD plans to use 26 of its nearly 500 KC-135s for airlift missions. 

SOURCE: Congressional Budget Office.


duced in larger quantities for the commercial market, they tend to cost less to purchase than military transports.

With about 190 operating, the C-141 is the most common type of airlift plane in the military fleet.(1) Those aircraft provide nearly 9 million ton-miles per day (MTM/D) of theoretical capacity--slightly less than a third of the total for military airlift planes in 1996. The Air Force considers the C-141 its core airlifter because the plane can be used not only to deliver cargo but also to conduct special military missions such as air-dropping Army paratroopers and their equipment.
 
But the C-141 is reaching the end of its service life, and recent experience has led military leaders to question its reliability. In 1993, an Air Force advisory board recommended restricting the weight of cargo that each one can carry. Inspection of the C-141 fleet revealed cracks in the weep holes where fuel circulates within the plane's wings and in some wingboxes that secure the wings to the fuselage. The Air Force repaired some of its C-141s to retain fleet capacity over the next few years, but it also decided to accelerate the plane's retirement. Current plans call for withdrawing the C-141 from active forces by 2003 and from reserve components by 2007.

Because of the sheer number of C-141s in service, that plane has been considered the workhorse of the military's strategic airlift fleet. But nearly 50 percent of the military's theoretical airlift capacity comes from C-5s (see Figure 2 on page 11). Seventy-six A model aircraft were built during the early 1970s and were retrofitted with new wings during the mid-1980s. Beginning in 1986, the Air Force took delivery of 50 new C-5Bs.

Unfortunately, the C-5 (the older A model in particular) has been plagued by low rates of reliability and maintainability. During the Persian Gulf War, an average of more than 30 percent of the Air Force's C-5s were unavailable because they needed maintenance, lacked spare parts, or both.(2) As it is flown and operated today, a C-5A requires about 56 hours of maintenance for every hour of flight, and the B model needs 29 hours per flight hour. The Air Force is considering retiring its C-5As beginning in 2007--even though the average C-5A has just 15,000 flight hours on its airframe out of an expected service life of 30,000 hours.(3)

The Administration plans to use 120 C-17s (102 primary aircraft authorized, or PAA) as the replacement workhorse for more than 200 C-141s. As of December 1996, the Air Force had contracted for 48 C-17s. Twenty-four of those are already operating and contribute about 3 MTM/D of DoD's theoretical airlift capacity. The C-17 has a system of thrust-reversers, flaps, and slats that allows it to land on short or ill-equipped airfields much as the C-130 (the Air Force's primary tactical airlift plane) does. Some military planners would like to use the C-17 to deliver cargo from the United States directly to airfields at the battlefront, rather than transferring equipment from main operating bases by means of ground transportation or on C-130s.

During the mid-1980s, the Congress appropriated funds to purchase 60 KC-10 aircraft (54 PAA), which can be used as either aerial refueling tankers or airlift-ers. More than two-thirds of those planes are dedicated to an airlift role and provide nearly 4 MTM/D of DoD's theoretical airlift capacity. In the event of a conflict, the Air Force also plans to use a few of its many KC-135 tanker aircraft to carry logistical supplies between military bases, thereby reducing the demand for other military transports.

The Civil Reserve Air Fleet

CRAF is a voluntary partnership between DoD and commercial air carriers designed to provide additional passenger and cargo planes and aeromedical evacuation services to the military during times of crisis. Both cargo and passenger air carriers participate in one of three stages of the program, which reflect the priority with which planes might be called into service (see Box 3). Planes in Stage I would be called into service most quickly, whereas those in Stage III would be activated only in the event of a national emergency.

As of January 1997, 11 passenger and 16 cargo airlines had enrolled a total of 508 long-range international aircraft in CRAF. If a national emergency occurred today, commercial passenger planes would carry the vast majority of all military personnel who would be deployed to a major conflict. If fully mobilized, cargo carriers who participate in the program would contribute up to 27.8 MTM/D. However, since participation in CRAF has fluctuated over time, the Air Force counts on only about 20.5 MTM/D of cargo capacity from CRAF in its long-term planning, although it prefers to enroll more than that in the program.(4) Defense officials argue that if DoD used much more than that level in a major conflict, civil aircraft would congest airlift operations and make it difficult to complete deliveries of outsize cargo on military transports. (See Appendix B for more information on CRAF participation.)

Those numbers demonstrate the importance of CRAF: buying enough military planes to make up that capability would be expensive and might crowd out funding for other types of forces in the defense budget. DoD also avoids paying for most of the costs of operating and supporting those planes during peacetime. According to one study, the cost of replacing CRAF capacity with military transport planes over the past 30 years would have run to about $3 billion annually.(5)

On August 17, 1990, DoD called up Stage I of CRAF for the first time ever to support deployments for Operation Desert Shield. Even before that call-up, a number of air carriers had volunteered planes for the operation. Stage I provided the Air Force with 17 international passenger aircraft and 21 international cargo
 

Box 3.
 Activating the Civil Reserve Air Fleet
The Civil Reserve Air Fleet program was created under a plan issued in March 1952.  President Truman put forth the initial directive for CRAF by executive order.  From its inception, the program's main objective has been to provide for a quick transition of the existing civil air fleet from commercial operations to supporting military airlift in times of crisis.  

Today's program maintains a three-stage activation plan, introduced in 1963.  With the approval of the Secretary of Defense, the Commander in Chief of the U.S. Transportation Command (USTRANSCOM) initiates Stage I of CRAF (called Committed Expansion) when the military airlift fleet cannot meet deployment and other airlift requirements simultaneously.  Stage II, Airlift Emergency, is also activated by the Commander in Chief of USTRANSCOM with the approval of the Secretary of Defense.  That stage provides additional airlift beyond the Stage I amount when required for a major airlift emergency that does not warrant full mobilization of most of the nation's civil aircraft.  Stage III, designated a National Emergency, is the highest level of CRAF activation.  The Commander in Chief of USTRANS-COM activates Stage III with the approval of the Secretary of Defense in time of war or a defense-oriented national emergency declared by the President, in a national emergency declared by the President, in a national emergency declared by the Congress, or in a national security situation before the declaration of a defense-oriented national emergency.

 
planes. On January 17, 1991, Secretary of Defense Dick Cheney activated Stage II of CRAF, providing 77 international passenger and 39 international cargo planes and their aircrews. In addition, at various times air carriers volunteered another 16 to 36 cargo aircraft. In total, U.S. airlines transported nearly two-thirds of the military personnel and one-quarter of the cargo airlifted during the Persian Gulf War. Air carriers also flew additional missions, delivered mail, and transported cargo on the ground between airports.

Although the activation of CRAF during the Persian Gulf War was generally considered a success, some air carriers--particularly larger airlines--fear that if many of their planes are called away from their commercial routes in the future, U.S. companies might lose market share to foreign rivals and never regain it. Those and other concerns about the program led some carriers to leave CRAF after the 1991 war.

In recent years, DoD and the General Services Administration have made participation in CRAF a prerequisite for firms bidding on the federal government's passenger air travel. That program, known as City Pairs, has expanded the amount of peacetime passenger business associated with CRAF from about $345 million a year to more than $1.5 billion. In addition to that business, DoD awards about $270 million a year to commercial carriers for cargo transportation services. DoD also plans to expand the federal government's small-package air transportation business to CRAF, and under certain circumstances, it is making military airfields available for use by commercial airlines.

CRAF participants generally cite two motives for taking part in the program: patriotism and peacetime business. Although the first motive is certainly important, the amount of peacetime business tied to CRAF has a strong effect on participation. With the end of the Cold War, some carriers anticipate a decline in the need for peacetime airlift and have expressed concern that the Air Force will no longer offer adequate incentives for them to remain in the program. Analysts, however, note that by replacing C-141s with a smaller number of C-17s, the Air Force will have fewer planes in its airlift fleet. Thus, DoD may actually need more airlift services from the commercial sector.

Can DoD continue to count on CRAF for the future? Today, most analysts would say yes; participation in the program is generally regarded as strong. The relative health of the U.S. airline industry is the foundation for that strength. But participation in CRAF will fluctuate over time. Financial downturns within the industry, such as those that led to the bankruptcy of Pan Am, may affect the future supply of aircraft to CRAF. And changes within the airline industry, such as international code-sharing alliances between airlines in different countries, could reduce the number of U.S. long-range international aircraft or their flexibility to participate in CRAF. That could happen if domestic carriers depended on foreign carriers (who are ineligible to participate in CRAF) to operate international routes.



Plans for Modernizing Military Airlift

For over a decade, DoD's plans to modernize its airlift fleet have focused on the C-17. When it began developing the plane in 1979, the military planned to buy 210 C-17s. That number was scaled back to 120 in 1990, however, following a review of the aircraft program. In December 1993, Administration officials limited C-17 purchases to 40 and put the program on probation for two years because of its significant cost growth and difficulty achieving performance goals.(6)

The two-year probationary period gave the plane's producer, McDonnell Douglas, a chance to show whether it could control costs, meet the delivery schedule, and improve quality. During the period, Mc-Donnell Douglas reduced its estimate of production costs and lowered the number of defects on planes coming off the manufacturing line. And in a monthlong evaluation in July 1995, the Air Force and McDonnell Douglas demonstrated that the C-17 can operate at its planned wartime rate of 15.2 hours per day.

After observing how the initial squadron of C-17s operated and reviewing the costs and capabilities of two alternative airlift planes, the Administration announced in November 1995 that it would plan and budget for 80 additional C-17s--for a total of 120 planes. The Congressional Budget Office (CBO) estimated that at the annual rates of production considered at the time, ac-quiring 80 more C-17s would cost $25.4 billion (in current dollars).(7) Defense officials subsequently proposed buying C-17s at a faster pace than that used in CBO's estimate: McDonnell Douglas now plans to build a maximum of 15 aircraft a year, with the final five planes in 2003.

In February 1996, DoD's Defense Acquisition Board recommended a plan to buy those planes under a multiyear contract, which the Congress authorized in April. Under the multiyear arrangement, the Air Force will apply $300 million in appropriations from previous years to finance additional cost-reduction initiatives for the C-17 production line and to buy large quantities of parts. CBO estimates that acquisition costs under that plan will total $23.8 billion (in current dollars) over the 1997-2004 period (see Table 3).

The Administration estimates that the average procurement cost per plane under the multiyear plan will be $225 million (in 1997 dollars). That figure includes the cost of associated support and initial spare parts for the 80 planes. By itself, accelerating C-17 production to a rate of 15 per year lowers the program's total acquisition costs by over $800 million (in current dollars) as a result of efficiencies in production. Multiyear contracting saves an additional $1 billion, or 5.6 percent.

Although it would help achieve greater efficiencies in production, multiyear procurement for the C-17 does have some drawbacks. Most notably, the long-term plan could lead to higher costs if competition for funding from other areas of the budget led future Congresses to decide to buy fewer than 80 more C-17s or to procure the planes at a lower rate than 15 per year. If the program was stopped before the 80 additional planes were built, the government would lose any funding that the Congress had already appropriated for advance procurement, and DoD would have to pay some costs for discontinuing the production line. It would also have incurred costs associated with building up an inventory of C-17 parts, some of which would never be used. If the Congress chose to buy 80 more C-17s but over a longer period of time (that is, fewer each year), DoD would have to renegotiate a higher annual purchase price with McDonnell Douglas.



Missions That Determine DoD's Requirements for Strategic Airlift

DoD officials base their numerical requirements for strategic airlift planes on two types of capabilities: the ability to deploy cargo, both during peacetime and to a



 
Table 3.
Procurement of C-17s Under the Administration's Plan, 1997-2004
(Costs in millions of current dollars)
Total,
1997-
1997 1998 1999 2000 2001 2002 2003 2004 2004
Quantity Previously Under
Consideration 8 8 8 10 12 12 12 10 80
Acquisition Costs a 2,760 2,820 2,840 3,210 3,600 3,590 3,570 2,960 25,350
Quantity in the Administration's
Current Plan 8 9 13 15 15 15 5 0 80
Acquisition Costs b 2,550 2,840 3,820 3,990 4,100 3,970 2,100 420 23,790
SOURCE: Congressional Budget Office based on data from the Department of Defense.
NOTE: Acquisition costs include procurement; research, development, test, and evaluation; military construction; and procurement of equipment for modifications.
a. Estimates based on annual-procurement contract strategy.
b. Estimates based on multiyear-procurement contract strategy.


major regional conflict; and the ability to perform special military missions such as air-dropping forces after traveling long distances. Although civil-style planes can help meet the first need, the Administration contends that DoD requires large numbers of military aircraft for the second. But historically, DoD has conducted airdrops only rarely.

The Administration's recent recommendation to buy 80 more C-17s was based in part on the design features of the plane that allow it to perform special missions. Those C-17s are expected to cost significantly more than alternative airlift planes or other types of strategic lift. Ultimately, the Congress's decisions about spending extra resources on C-17s depend on whether the United States might need to conduct special airlift missions in the future and on how much it is willing to pay for the plane's capabilities.

Cargo Deliveries to Major Conflicts

Military planners divide airlift loads into three sizes: bulk loads that fit on a standard pallet, oversize loads that are larger than bulk loads but will fit in a C-141, and outsize loads that can fit only in a C-5 or C-17. Since the military uses many heavy vehicles and awkwardly shaped pieces of equipment, having transport planes that can accommodate that cargo is important.

The mix of equipment DoD would airlift to a major regional contingency today differs from what it planned to send for a conflict with the Soviet Union. According to a 1981 study of mobility requirements, 27 percent (by weight) of the equipment that DoD planned to send to a NATO/Warsaw Pact conflict within the first two weeks was outsize. By comparison, DoD's more recent simulations of deployments to Korea and the Persian Gulf region suggest that 15 percent to 18 percent of airlift deliveries over a similar period would be outsize. Official data for the first two weeks of Operation Desert Shield are unavailable, but during the first month of deployments, approximately 10 percent (by weight) of the cargo loads were outsize and half were bulk.(8)

The decline in the relative need to carry outsize cargo is an important issue in deciding how many military planes like the C-17 are necessary. One advantage of C-17s and C-5s over civil-style planes is their ability to carry such cargo. However, if a large proportion of the equipment that DoD plans to send can fit on modified civil-style planes, DoD might need fewer C-17s.

In 1995, the Pentagon evaluated two alternatives to the C-17: the C-5's D model and the C-33, a military version of Boeing's 747-400 freighter.(9) Both planes were expected to cost less than the C-17, and each could carry a much larger average payload. Air Force analysts used detailed simulations to estimate how much cargo various combinations of C-17s and either C-33s or C-5Ds could deliver in the first two to three weeks of major conflicts in Korea and the Persian Gulf. They then compared the performance of those alternatives with that of an airlift fleet containing 120 C-17s.

The results of their analysis showed that various mixtures of planes were capable of handling deliveries to major regional contingencies, although not quite as well as a fleet with 120 C-17s. Consider a conflict on the Korean Peninsula--a scenario that defense officials argue would be the most taxing on airlift because of congested airfields. Under crowded conditions, one might expect fleets with large planes such as the C-33 or C-5 to deliver substantially less cargo than fleets made up entirely of the smaller and more maneuverable C-17.

In fact, the Air Force analysis showed that although combinations of C-17s and C-33s or C-5s could not deliver as much outsize equipment as 120 C-17s, some alternatives came close. For example, a combination of 58 C-17s and 42 C-33s would deliver 97 percent or more of the amount that 120 C-17s could provide. That mix of planes would complete its deliveries to the Korean Peninsula about one to two days later over a two- to three-week period. According to DoD's estimates, that fleet would cost $11.5 billion less (in 1996 dollars) than 80 more C-17s over the course of the planes' service lives.

If ramp space is limited at airfields in a theater of operations, the C-17's advantage is more pronounced. When the Air Force analysis constrained ramp space at Korean airfields by an additional 15 percent, the fleet of 120 C-17s increased the margin by which it could deliver more outsize cargo than mixtures of C-17s and C-33s. Nevertheless, fleets containing as few as 72 C-17s and 30 C-33s would be able to transport 94 percent or more of the amount of outsize cargo delivered by 120 C-17s, but would cost at least $8 billion less over their projected service life. Since the Air Force expects that more ramp space would be available for airlift planes in the Persian Gulf, combinations of C-17s and C-33s performed better in that scenario than in the Korean case.

To summarize, various combinations of C-17s and C-33s could deliver nearly as much cargo during the first two to three weeks of a conflict on the Korean Peninsula as an airlift fleet with 120 C-17s. The slower pace of deliveries with those mixed fleets could add one or two days to the time needed to finish delivering U.S. forces to the region, and perhaps a week if airfield space was constrained by an additional 15 percent. But DoD officials emphasized alternatives that precisely matched the capability of 120 C-17s rather than options that were slightly less capable at delivering cargo to a major conflict but were much less costly.

Cargo Deliveries to Smaller Operations

Although major conflicts would be the most demanding, smaller deployments could also tax airlift forces because DoD might not call up reserve aircrews or activate the Civil Reserve Air Fleet. Thus, fewer planes-- civil or military--would be available for peacetime missions. If the United States needed to conduct operations in regions with short runways or poorly equipped airfields, DoD officials argue, a larger number of C-17s would allow them to deploy forces more quickly.(10) For example, in the recent deployment of U.S. forces to Bosnia for Operation Joint Endeavor, the Air Force flew only C-130s, C-141s, and C-17s into Tuzla airfield because of its small width and limited ramp space.

But how many C-17s would be needed for smaller cargo deliveries? In many cases, the answer appears to be 40 or fewer. In a 1995 study of the tactical utility of various airlift fleets, the Secretary of Defense's Director for Program Analysis and Evaluation looked at what the Administration considers representative cases of four types of smaller missions: a peacekeeping operation, a humanitarian assistance mission, an evacuation of noncombatants from a foreign country, and a peace enforcement operation. The specific assumptions for each scenario were taken from the Administration's Defense Planning Guidance and from intelligence information. The analysis did not examine cases in which the United States conducted several such missions at once, which would most likely raise requirements for airlift.

For peacekeeping missions, the United States would deploy forces to maintain an existing truce, such as in current United Nations operations in the Sinai. Defense officials believe that airlift fleets with as few as 40 C-17s could conduct deployments to a representative peacekeeping operation with little risk of failing to achieve DoD's military objectives. DoD leaders reached the same conclusion for the representative humanitarian mission, which was similar to the delivery of food, medicine, and desalination equipment to Rwanda in 1994, and for an evacuation of noncombatants, similar in nature to the recent evacuation of U.S. citizens from Liberia.

However, one type of mission for which DoD might need more C-17s is a peace enforcement operation, in which U.S. forces would help keep regional foes from fighting one another. (Operation Joint Endeavor in Bosnia is an example of a current peace enforcement operation.) That sort of mission would require deploying heavier forces in order to protect U.S. troops from artillery fire, snipers, and the like.(11) DoD officials concluded that airlift fleets with 72 or 86 C-17s could complete deliveries to such an operation in a short enough time that U.S. forces would face moderate risk of failing to achieve their military objectives. If U.S. airlift forces included 100 or more C-17s, defense officials believe, they could complete deliveries quickly enough to keep the risk at a low level.

But the amount of gross tonnage that an airlift fleet can deliver to major conflicts or smaller missions was not the only basis for the Administration's November 1995 decision to buy a total of 120 C-17s. According to press accounts, DoD's tactical requirements for conducting special airlift missions were the key reason that Administration officials made that recommendation.(12)

Special Airlift Missions

If DoD needed to prepare for other, more specialized types of airlift operations, it might require larger numbers of C-17s. One such mission is an airdrop operation in which airlift planes would deliver paratroopers and equipment from the air after traveling intercontinental distances. Shortly after the initial airdrop, DoD would deliver additional equipment the traditional way by landing cargo planes.

The Air Force now relies on the C-141 and C-130 as the principal platforms for air-dropping paratroopers and equipment. (Most C-130s cannot be refueled in flight, so only the C-141 can be used in situations involving airdrops over intercontinental distances.) Despite some difficulties in airdrop tests, the Air Force and Army have committed themselves to using C-17s as the replacement for C-141s in that role.(13)

Without the C-141, DoD officials believe, the Air Force would need at least 100 C-17s to air-drop a "medium force package" consisting of 2,552 Army paratroopers and the equipment for the lead brigade that would deploy first from the airborne division. Since each C-17 can drop 102 paratroopers, DoD would need 25 planes simply to air-drop personnel. The remaining C-17s, along with 50 C-5Bs, would air-drop equipment and then deliver additional cargo to support those troops by conventional operations. (The Army does not use C-5Bs to air-drop troops because of concerns about their safety.) A fleet that included 120 C-17s could conduct such a mission with low risk of failure, according to defense officials.

The Secretary of Defense's Director for Program Analysis and Evaluation also examined how many airlift planes would be needed today to conduct airdrop operations like those for the 1989 U.S. deployment to Panama known as Operation Just Cause. Since Panama lies within the range of the C-130, the Air Force could use those tactical airlift planes to support such an airdrop. However, defense officials concluded that the Air Force would need at least 86 C-17s in its fleet to conduct a similarly sized airdrop with moderate risk within the time frame laid out by military planners. Fleets with 100 or more C-17s might allow the Air Force to air-drop more forces or conduct the mission with lower risk of failure. The Army believes that it would need at least 120 C-17s to meet its requirements for a brigade- size airdrop over strategic distances.

Should the United States buy enough C-17s to conduct long-range airdrops of brigade-size forces? Military planners argue yes, since doing so would give the United States the ability to enter countries forcibly anywhere in the world. But the United States has rarely air-dropped paratroopers in actual missions. Airborne forces were dropped during Operation Urgent Fury in Grenada in 1983 and in 1989 during Operation Just Cause in Panama. And arguably, DoD's preparations in September 1994 for a parachute assault into Haiti helped convince that country's military rulers to accept the more peaceful introduction of U.S. forces.

However, in all of those cases shorter-range C-130s could be used. A brigade airdrop over an intercontinental distance would be considerably more demanding on paratroopers: before conducting their jump, they would have to fly long stretches on planes designed primarily to move cargo, conduct a parachute assault to seize and secure an airfield, and then prepare to receive reinforcements from traditional airlift deliveries. The complexity of such an operation has led some analysts to suggest that it is an unlikely event. Other analysts, however, argue that retaining such a capability would deter potential aggressors.

Another type of special airlift mission is delivering cargo from the United States directly to the front of a conflict in the midst of major strategic deployments, such as to forward bases near the border of North and South Korea. A 1995 DoD study found that a fleet with as few as 72 C-17s (when combined with C-33s) could provide the capability to deliver units directly to the front. But such a fleet would complete those deliveries more slowly than one with 120 C-17s, and thus DoD officials characterize the risk of failure associated with that slower pace as moderate.

Dedicating one or two squadrons of strategic airlift planes to moving cargo within a theater of operations is another mission that could require larger numbers of C-17s. Since it can carry outsize pieces of equipment, the C-17 could be used to move some high-priority cargo within a theater that C-130s cannot, such as batteries of Patriot missiles or multiple-launch rocket systems.

Defense officials believe a fleet with 86 C-17s and 30 C-33s could complete strategic deliveries for a major conflict in a timely manner. If military commanders chose to use C-17s to move equipment within a theater, however, fewer C-17s would be available to deploy forces from the United States, and thus deployments would take more time and involve higher risk. Military leaders recommend buying at least 14 additional C-17s for intratheater deliveries, although the Office of the Secretary of Defense has not yet endorsed that idea.

Some analysts would question the importance of using C-17s in that way, however. Today, military commanders use trucks or railcars to transport outsize cargo within a theater of operations, and those modes would still be available in future conflicts. Given the high cost of C-17s, some policymakers might consider dedicating one or two squadrons of them to that role as unaffordable.


1. That number represents primary aircraft authorized, which excludes planes that are undergoing depot maintenance or being held as reserves against attrition.

2. John Lund, Ruth Berg, and Corinne Replogle, An Assessment of Strategic Airlift Operational Efficiency, R-4269/4-AF (Santa Monica, Calif.: RAND, 1993), pp. 53-55.

3. According to a General Accounting Office study, the Air Force might be able to make more of its C-5s available if it improved its process for supplying spare parts and conducted a readiness evaluation similar to that completed for the B-1B aircraft. See GAO, Strategic Airlift: Improvements in C-5 Mission Capability Can Help Meet Airlift Requirements, GAO/NSIAD-96-43 (November 1995).

4. The passenger planes that carried troops would also deliver a significant amount of cargo at the same time, but the Air Force does not include those deliveries in its calculations of theoretical airlift capacity for cargo.

5. Jean R. Gebman, Lois Batchelder, and Katherine Poehlmann, Finding the Right Mix of Military and Civil Aircraft: Issues and Implications, vol. 2, Analysis, MR-406/2-AF (Santa Monica, Calif.: RAND, 1994), p. 44.

6. For a discussion of the cost and performance issues in the C-17 program, see Congressional Budget Office, The C-17: Costs and Alternatives, CBO Paper (August 1993); and General Accounting Office, C-17 Aircraft: Cost and Performance Issues, GAO/NSIAD-95-26 (January 1995).

7. Congressional Budget Office, Options for Strategic Airlift, CBO Memorandum (October 1995), p. 22.

8. Gebman, Batchelder, and Poehlmann, Finding the Right Mix of Military and Civil Aircraft, p. 26.

9. For a discussion of the costs and capabilities of three alternative airlift purchases, see Congressional Budget Office, Options for Strategic Airlift.

10. The C-17 was designed to land on runways as short as 3,000 feet, whereas the only other plane in the Air Force's inventory that can carry outsize cargo, the C-5, typically requires a runway of nearly 5,000 feet. In considering both runway length and the weight-bearing capacity of runways around the world, DoD estimates that the C-17 can land on approximately 3,700 airfields outside the United States, compared with 2,300 for the C-5.

11. For Joint Endeavor, U.S. military leaders originally planned to deploy a peak of 20,000 troops to the region over an eight-week period, including an aviation brigade, two brigades from the 1st Armored Division, and support and sustainment forces.

12. Elaine M. Grossman, "Tactical Utility Analysis Proved to be Key Factor in DAB's C-17 Decision," Inside the Pentagon, November 16, 1995, pp. 3-4.

13. Tony Capaccio, "C-17 Still Can't Perform Crucial Army Airdrop Mission," Defense Week, November 4, 1996, p. 1.


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