NAVY AIRCRAFT CARRIERS|
Cost-Effectiveness of Conventionally and Nuclear-Powered Aircraft Carriers
GAO/NSIAD-98-1 -- August 1998
Appendix VII COMMENTS FROM THE DEPARTMENT OF DEFENSE ========================================================== Appendix VIIThe following are our comments on DOD's letter dated March 30, 1998. GAO COMMENTS 1. We note that conventionally powered carriers have been upgraded with new features. During their midlife modernization periods, the carriers received extensive rehabilitation and upgrading of their hull, propulsion, auxiliary machinery, electrical and piping systems, improved radars and communications equipment, and aircraft launch and recovery systems. Kevlar armor was added to vital spaces. As part of the Navy's Fleet Modernization Program, the fleet is continuously upgraded with new weapons and electronics systems, as well as other features. For example, one of the conventionally powered carriers, the U.S.S. Constellation (CV-64), has received several upgrades to its aviation maintenance equipment; intelligence, combat, engineering, and navigation systems; and habitability, and it embarks the newest and most capable aircraft that exist in the Navy. At the time of our visit to the U.S.S. Kitty Hawk (CV-63), the commanding officer told us that it had the most modern systems installed in the command, control, communications, computers, and intelligence (C4I) area and that its joint force air component commander (JFACC) is the model for West coast carriers. Another conventionally powered carrier, the U.S.S. John F. Kennedy (CV-67), was the first carrier to operationally deploy with two state-of-the-art intelligence systems, the Battle Group Passive Horizon Extension System and the Common High Bandwidth Data Link. The conventionally powered carriers also are scheduled to receive cooperative engagement capability\1 along with their nuclear-powered counterparts. We disagree that a new design conventionally powered carrier would necessarily result in a larger and heavier ship. The assumptions underlying this statement disregard the space and weight made available through adopting new technologies and the reduced personnel requirements for the ship and its air wing. Personnel reduction goals for the next carrier ship's force are about 50 percent. Potential air wing reductions can be illustrated by the personnel savings expected in replacing F-14A squadrons with two-seat F/A-18E/F squadrons. An F-14 squadron generally requires 275 maintenance personnel, while an F/A-18E/F squadron will require about 180, a reduction of about 35 percent. For an air wing of 2,480 persons, this could result in a reduction of about 870 persons. Cumulatively, these reductions are expected to require less demand for hotel services such as mess halls, berthing, laundry, and food stores and free up space and weight for aviation fuel and ordnance. 2. We believe the measures of effectiveness we chose are appropriate for comparing the two types of carriers. Our methodology for evaluating the effectiveness of conventionally and nuclear-powered carriers uses performance-based mission outcomes (national security objectives) as its metric and is not engineering requirements derived (maximum speed or load carrying capacity). We coordinated our measures of effectiveness with Joint Staff, Office of the Secretary of Defense, and Navy officials. In fact, some senior Navy officials said that they believed that our methodology was sound. 3. We do not state that carriers operate exclusively with battle groups. Rather, we state that a battle group's composition can vary depending on the mission need. For example, figure 1.1 and related text shows a CVN ¹surgingº from the Mediterranean Sea to the Gulf, with elements of its battle group, including a supporting fast combat support ship. The carrier left five of its battle group ships in the Mediterranean Sea, including a nuclear-powered cruiser. 4. Our analysis of the ship deck logs for the U.S.S. Nimitz does not support DOD's statement. According to the logs, ships of the U.S.S. Nimitz battle group passed through the Strait of Hormuz around 6:00 p.m. on March 12, 1996, while the U.S.S. Nimitz exited the Strait of Hormuz around 10:00 a.m. on March 14, 1996, approximately a day and a half later. We note that while the U.S.S. Nimitz and one escort remained in the Gulf, several other ships of the separate Middle East Task Force operated in the Gulf. The average transit speed of the U.S.S. Nimitz to the South China Sea was less than 20 knots. 5. While we agree that conventionally powered carriers are more dependent on battle group logistics support than nuclear-powered carriers, we do not agree with DOD that fuel consumption concerns limit conventionally powered carriers to the slower speeds of logistics ships. We note that the AOE-class battle group supply ship can sustain speeds of 30 knots and thus will not limit the transit speed of the battle group. In situations where an AOE is not available, the Combat Logistics Force can resupply fuel oil with its worldwide network of prepositioned oilers. Logistics force planners and operators told us they knew of no time when a conventionally powered carrier could not obtain Combat Logistics Force support during peacetime or crisis. Recently, the conventionally powered carrier U.S.S. Independence (CV-62) traveled from its homeport in Yokosuka, Japan, to the Arabian Gulf at an average speed of 24 knots. During the transit, the ship sustained speeds of at least 27 knots over two-thirds of the time. 6. We added information on more recent carrier deployments to appendix IV. 7. Our report states that the maintenance strategy, along with propulsion type, affects the length of a carrier's employment cycle. Although the Navy's guidance for accomplishing ship depot-level maintenance availabilities nominally sets depot intervals, durations, and mandays by ship class, the Navy has deviated from this guidance for conventionally powered carriers and nuclear-powered cruisers that have been grouped by type for at least the last 8 years. We note that nuclear propulsion maintenance requires exacting and stringent environmental, health, and safety standards. Our analysis shows that, under the Navy's current strategy, nuclear-powered surface ships have longer depot-level maintenance periods than their conventionally powered counterparts. For example, the typical post-deployment maintenance period for a nuclear-powered carrier lasts 6 months and about 62 percent of the work is related to the propulsion plant. The typical post-deployment yard period for a conventionally powered carrier is about 3 months. The nuclear-powered carrier spends more time undergoing propulsion plant work than the conventionally powered carrier does for all its maintenance, repairs, and modernization. A similar relationship exists between conventionally and nuclear-powered surface combatants. Our analysis also shows that a conventionally powered Aegis cruiser or Kidd-class guided-missile destroyer spends about one-fourth the maintenance mandays per deployment as a nuclear-powered cruiser. Furthermore, our analysis shows that a conventionally powered surface combatant spends about 16 percent of its time in depot-level maintenance compared to around 25 percent for a nuclear-powered cruiser. As shown in table VII.1, the nuclear-powered cruiser maintenance cycle is more like a conventionally powered carrier than a conventionally powered cruiser in terms of the time spent in maintenance (about 25 percent) and mandays of work to perform the maintenance (about 38,000 mandays after a typical deployment and over 300,000 mandays for a complex overhaul). Table VII.1 Maintenance Period Characteristics of Conventionally and Nuclear-Powered Surface Combatants and Aircraft Carriers Typical post- deployment depot maintenance period Complex overhaul -------------------- -------------------- Cycle time in Mandays Mandays maintenance (thousands (thousands Ship type (percent) Months ) Months ) ------------------ ---------------- -------- ---------- -------- ---------- Surface combatant -------------------------------------------------------------------------------- Conventionally 16 2-3 10 8.0 48 powered Nuclear-powered 24 3-4 38 18.0 350 Aircraft carrier -------------------------------------------------------------------------------- Conventionally 25 3 45 12.0 376 powered Nuclear-powered 29 6 162 10.5 289 -------------------------------------------------------------------------------- Source: Our analysis of Navy data. 8. The September 1997 Chief of Naval Operations memorandum stated that to prevent confusion and misunderstanding, the OPNAV Notice 4700\2 is being revised to reflect these comments. The OPNAV Notice 4700 has not been revised to reflect that information. 9. We included information on the arguments that led to the use of nuclear propulsion for surface ships in the 1960s to provide important historical context for the debate. We did not discuss the arguments that culminated in approval of nuclear propulsion for the Nimitz-class because DOD was unable to provide us with supporting documentation. However, we understand that many of the arguments in favor of nuclear propulsion were the same as those presented in the 1960s. 10. While DOD said that the risk and cost associated with developing the new Aegis capability in parallel with the new design nuclear propulsion plant were factors in its choice of choosing conventional power for Aegis cruisers, it provided no evidence to support this belief. The Secretary of Defense's assessment was that ¹the military value of an all nuclear-powered Aegis ship program does not warrant the increased costs or, alternatively, the reduced forced levels.º DOD was unable to provide support for its rationale for deciding to retire the nuclear-powered surface combatants at an average age of 17 years. Instead, it provided Navy point papers that noted adding the New Threat Upgrade (NTU) will provide extremely capable anti-air warfare for 10 plus years--combat system capabilities comparable to AEGIS ships and an engagement range greater than AEGIS (until introduction of the Standard Missile (SM2) Block 4 to AEGIS cruisers). The point papers also stated that the nuclear-powered surface combatants are (1) superior to all surface combatants in tactical mobility and (2) the only combatant escorts that do not constrain a CVN battle group's mobility, flexibility, and rapid surge capability--¹an essential element of the future force structure.º 11. We were asked to assess the cost-effectiveness of conventionally and nuclear-powered carriers and did not perform any comparisons of the advantages and costs of using nuclear power in surface ships versus aircraft carriers. 12. Our congressional mandate was to review the cost-effectiveness of conventionally versus nuclear-powered carriers, not to develop potential designs for a new carrier or to evaluate the cost-effectiveness of such designs. We do not agree that a cost-effectiveness analysis should assume that the next conventionally or nuclear-powered carrier would have the same capabilities and features, nor do we agree that the highest end technology should be assumed in the analysis. Rather, the goal of designing a new carrier is to build a system with the capability necessary to meet U.S. national security objectives. We also note that the Center for Naval Analyses used a methodology similar to ours in some preliminary work it did for the Navy as the Navy began to assess its future carrier needs. This historical perspective covered a wide range of peacetime forward presence, crisis response, and war-fighting scenarios that both types of carriers have faced for over two decades. We believe this provides a sound foundation for evaluating the relative cost and effectiveness of these two ship types. Although DOD said that the current assessment of a new carrier design would include various features, including new fossil fuel and nuclear-powered designs, we note that in the 1998 Navy Posture Statement, the Secretary of the Navy and the Chief of Naval Operations state, ¹This next generation nuclear-powered aircraft carrier is scheduled to begin construction in 2006. . .º and ¹CVX will be the most technologically advanced nuclear-powered carrier the Navy has ever developed.º 13. We believe the report adequately addresses the support required for both types of carriers. For example, it specifically states that nuclear-powered carriers can transit long distances faster because, unlike conventionally powered carriers, they do not need to slow for underway replenishment of propulsion fuel. It also included a table comparing nuclear and conventionally powered carrier transit times that highlights refueling requirements for conventionally powered carriers. We note that DOD's comment that operational commanders task the closest or next-to-deploy carrier rather than selecting a particular carrier is consistent with our finding that the carrier's type of propulsion is not a critical factor in making employment decisions. We also note that the vast majority of Navy ships are fossil fuel-powered, thereby necessitating a continuous logistics presence. In fact, the Navy has specifically designed and strategically located its logistics infrastructure to provide continuous support to peacetime and wartime naval operations. Elements of the logistics infrastructure include naval depots, inventory control points, distribution centers and bases in the United States; advanced overseas support bases located in or near the theater of operations; and a highly mobile fleet of Combat Logistics Force ships that carry a broad range of supplies. Logistics planning to provide that support is a continuous, organized process, performed in parallel with naval operations planning. A recent example that we believe demonstrates the timeliness and effectiveness of the Navy's worldwide logistics infrastructure was the unanticipated deployment of the conventionally powered U.S.S. Independence from Japan to the Persian Gulf in January 1998, during a confrontation with Iraq, to relieve the U.S.S. Nimitz. On January 21, 1998, the Secretary of Defense ordered the U.S.S. Independence to depart for the Persian Gulf. The carrier got underway on January 23, 1998, and conducted a high-speed transit to the Persian Gulf, arriving on February 5, 1998. During the voyage, the carrier was replenished by three separate Military Sealift Command tankers, already prepositioned in the western Pacific and Indian Ocean areas. Crisis logistics planning enabled the tankers to rendezvous with the carrier to provide needed replenishment without hindering the carrier's ability to respond in a timely manner to fulfill its tasking. 14. Our analysis shows that a conventionally powered carrier steaming at 28 knots would cover 6,740 nautical miles (a distance equivalent to that from Norfolk to the Red Sea) in about 9-1/2 days and arrive with 77 percent of its propulsion fuel remaining. We project that the AOE-6 would still have over 11,700 barrels of DFM remaining to give to other ships. (Our analysis assumed that the AOE-6 had a maximum capacity of 93,600 barrels of DFM. Of this amount, 30,950 barrels would be needed for the AOE-6's own propulsion, leaving 62,650 barrels available to refuel other ships--the carrier would need 50,893 barrels.)\3 Our calculations were based on published fuel consumption rates from the ships' engineering manuals, fuel capacities from ship manuals, and the distances cited in the example. We calculated burn rates based upon the more demanding 28-knot transit vice DOD's 26-knot rate and we assumed that the carrier would be refueled when its DFM levels reached 70 percent of its capacity. Our analysis is very conservative because our burn rates assumed all eight boilers being on-line when only five boilers need to be on-line to sustain a 28-knot speed for the U.S.S. John F. Kennedy (CV-67). 15. Subsequent to providing written comments on our draft report, DOD provided adjusted maintenance data that showed conventionally powered carriers were in depot- level maintenance about 32 percent of the time (26 percent when adjusted for the Service Life Extension Program (SLEP) and the Nimitz-class ships were in depot-level maintenance about 27 percent of the time. After receiving DOD's comments, we re-examined our methodology but could not replicate DOD's results. Our original results remained--each carrier type spent about 30 percent of its ¹unadjustedº time from October 1, 1984, to December 31, 1996, in depot-level maintenance availabilities.\4 We also examined two other time periods to gauge the variability of the results. According to our calculations, from October 1, 1982, through December 31, 1996, conventionally and nuclear-powered carriers were in the shipyards for depot-level maintenance 31 percent and 30 percent of the time, respectively, while accounting for 30 percent of the time for both carrier types from October 1, 1983, through December 31, 1996. In our draft report, we stated that, after adjusting for the time they spent in SLEP, the conventionally powered carriers collectively would have spent about 23 percent from October 1, 1984, through December 31, 1996, in depot-level maintenance--about 7 percent less than the nuclear-powered carriers. After receiving DOD's comments, we re-examined and modified our methodology for making the SLEP adjustment. According to our revised calculations, the conventionally powered carriers would have spent about 24 percent of their time in depot-level maintenance, about 6 percent less than the nuclear-powered carriers. Our adjustments have been incorporated into the report, and our methodology for adjusting SLEP time is discussed in appendix I. We also examined the effect that refueling overhauls would have on the time that the nuclear-powered carriers would spend in depot-level maintenance. According to current maintenance schedules, starting in mid-1998 and ending in mid-2007, one of the Nimitz-class carriers will be almost continually undergoing a refueling overhaul, a situation analogous to the conventionally powered carrier SLEPs in the 1980s and early 1990s (the notional durations of both a refueling overhaul and a SLEP is 32 months). We found, that from October 1, 1997, through December 31, 2007, the nuclear-powered carriers will spend about 32 percent of their collective time undergoing depot-level maintenance in a shipyard--about 2 percent more than during the original time period. The two operating conventionally powered carriers will spend about 19 percent of their time undergoing depot-level maintenance in a shipyard during this period. 16. We agree that, within the time period we examined, six of nine conventionally powered carriers were inactivated or were within 5 years of inactivation and that these ships would have received less maintenance and modernization. However, because of the timing of the inactivation decision and the actual inactivation, there would have been insufficient time to significantly decrease the amount of maintenance and modernization on the ships prior to their inactivation. For example, the decision to inactivate the Forrestal (CV-59), the Saratoga (CV-60), and the Ranger (CV-61) was first reflected in documents supporting DOD's Fiscal Year 1992 Future Year Defense Plan. The Forrestal and the Ranger were decommissioned in 1993 and the Saratoga was decommissioned in 1994. These three ships underwent regularly scheduled, and in some cases, extensive maintenance. For example, the Saratoga, underwent a comprehensive 15.9 month overhaul starting in January 1988 that lasted about 1-1/2 months longer than the average overhaul for all conventionally powered carriers. It also underwent SRAs that were longer than average SRAs in 1991 and 1993. Also, the Navy has approved modernization on carriers that are within 5 years of inactivation. For example, as we reported in 1997, the Navy plans to install an improved ship self-defense system on the U.S.S. Kitty Hawk in 2003, 5 years before its inactivation.\5 According to a carrier maintenance planning official, modernizations necessary for safe and effective operation can be and are applied to a carrier within 5 years of its inactivation, and the ship must be maintained so that it can complete its deployments. We agree that the Kitty Hawk/Kennedy-class carriers were older and may have required more maintenance. Those carriers were, on average, three times as old as the ships of the Nimitz-class, over the actual maintenance periods we examined. Because older ships require more maintenance, the data for the Kitty Hawk/Kennedy-class ships may reflect a lower availability than would the same ships if they were of similar age to the Nimitz-class. 17. Our work shows that nuclear-powered carriers spend more time in maintenance than do conventionally powered carriers. A key reason for the difference is propulsion plant work. According to the Navy's standard maintenance planning factors, a nuclear-powered carrier requires about 613,000 mandays of depot-level maintenance to complete three deployments, about 32 percent more than the 466,000 mandays a conventionally powered carrier requires. A carrier maintenance planning official said propulsion plant maintenance accounts for about 44 percent of the total repair mandays on both conventionally and nuclear-powered carriers. Moreover, according to a Puget Sound Naval Shipyard carrier maintenance report, in a nuclear-powered carrier's predominate post-deployment major maintenance period of 6 months, about 100,000 of the 162,000 notional mandays of work would involve nuclear propulsion plant work. Additionally, a document discussing the factors that must be considered when planning aircraft carrier maintenance ranked propulsion type as the second most important factor, after operational requirements. 18. DOD's assessment of the role maintenance schedules play in a ship's employment cycle relates more to conditions in a crisis situation vice normal peacetime operations. To illustrate, Navy doctrine, as outlined in Naval Warfare Publication 1, Strategic Concepts of the U.S. Navy, states that the length of the employment cycle for each ship class is based on the depot-level maintenance requirements for that class of ship. A regular maintenance program is essential so that operational commanders have ships with the material condition and capabilities to fight and win wars. Furthermore, Navy guidance contained in the Chief of Naval Operation's OPNAV Notice 4700, which provides definitive guidance concerning depot-level maintenance availabilities, states that ships shall accomplish depot maintenance availabilities at the notional intervals, durations, and repair mandays set forth. It also states that the durations specified provide the best notional estimates for long-range programming. To ensure compatibility with the ship's employment schedule and to facilitate depot work loading, it authorizes minor deviations from the notional depot availability interval. Commenting on the challenges of providing peacetime presence requirements and the relationship of ship maintenance and deployment schedules, the Commander in Chief, U.S. Pacific Fleet, recently stated, "The degree of attention required to manage many operational variables--maintenance, training, operating tempo (OPTEMPO), personnel percentage of time in homeport (PERSTEMPO), personnel rotation, new contingencies--is growing, and we are often forced to make tradeoffs...If scheduled maintenance for a ship gets delayed it directly impacts the maintenance, training, or PERSTEMPO of other ships." \6 The Eisenhower's experience during Desert Shield illustrates the degree of coordination between deployment needs and scheduled maintenance periods. The Eisenhower was not retained in the theater during the initial stages of uncertainty after the 1990 Iraqi invasion of Kuwait, but it returned to Norfolk for a previously scheduled maintenance period. 19. DOD's conclusion that the Navy will maintain a force of 12 carriers is based on an analysis of naval force structure options that it performed during its Quadrennial Defense Review (QDR). Using the Navy's Force Presence Model, DOD analyzed various aircraft carrier force structure options and compared them to the forward presence currently provided in the U.S. European Command, U.S. Central Command, and U.S. Pacific Command areas of responsibility. DOD concluded that a force of 11 active aircraft carriers plus one operational Reserve/training carrier was necessary to satisfy current policy for forward deployed carriers and accommodate real world scheduling constraints. Our analysis of the comparative number of conventionally and nuclear-powered carriers needed to meet overseas presence requirements was based on the Navy's Force Presence Model, which was also used in the QDR. Specifically, we used standard assumptions relating to carrier type maintenance cycle, average speed of advance, distance, PERSTEMPO restrictions, and length of deployments. We did not postulate what future carrier type maintenance cycles may or may not be in terms of mandays or durations. Although the maintenance strategy for conventionally and nuclear-powered carriers can be similar, the actual maintenance requirements for nuclear-powered carriers are very different than those for conventionally powered carriers. For example, carrier maintenance experts have told us that if an oil-fired steam boiler carrier were moved from its existing maintenance strategy, the EOC to an IMP type cycle, its profile would probably consist of two 4-month PIAs followed by a 8-month DPIA compared to the two 6-month PIAs followed by a 10.5-month DPIA for the nuclear-powered carriers. 20. Our analysis was intended to present a notional comparison of the differences in time between the two carrier types to cover the same distances at the same speeds when factoring in the impact of underway replenishment. We recognize that neither type would sustain high speeds during an entire long-distance voyage. Both types of carriers adjust their speed to control for the proper amount of wind-over-the-deck for air operations; accomplish underway replenishment; conduct propulsion plant drills, and rudder swing checks; and adjust to weather conditions. Nevertheless, both types of carriers can steam at high speeds and have demonstrated this capability for extended periods of time for many consecutive hours and even days. 21. We do not agree with DOD's figures on the amount of propulsion fuel and AOE fuel capacity that would be required for a conventionally powered carrier on a 4,800- and 12,000-nautical mile transit at 28 knots. Based on fuel consumption rates that the Navy provided to us, we found the following. -- A conventionally powered carrier steaming at 28 knots on a 4,800-nautical mile transit would require approximately 1.9 million gallons of replenishment fuel if it were refueled when its propulsion fuel reached 60 percent of its usable capacity. When the AOE fuel requirements (1.4 million gallons) for this voyage are added, a total of 3.3 million gallons of propulsion fuel would be required. This is the equivalent of 0.6 of an AOE based on an AOE's total usable ship propulsion fuel (DFM) capacity of 5.2 million gallons. If the carrier and the AOE were accompanied by a battle group of six fossil-fueled escorts (2 CG-47/52s, 2 DD-963s, and 2 DDG-51s), a total of about 7 million gallons of fuel would be required, the equivalent of 1.3 Sacramento-class ships. -- A conventionally powered carrier on a 12,000-nautical mile transit steaming at 28 knots would require approximately 4.75 million gallons of replenishment fuel if it were refueled when its propulsion fuel reached 60 percent of its usable capacity. When the AOE's fuel requirements (3.3 million gallons) for this voyage are added to the carrier's, a total of 8 million gallons of propulsion fuel would be required. This is the equivalent of 1.5 AOE ships. If the carrier and the AOE were accompanied by a battle group of six fossil-fueled escorts (2 CG-47/52s, 2 DD-963s, and 2 DDG-51s), a total of about 17.6 million gallons of fuel would be required, the equivalent of 3.4 Sacramento-class ships. 22. We based our transit time and fuel consumption comparisons on the assumption that the conventional carrier would have eight boilers on line for speeds of 28 knots or faster and four boilers for speeds below 28 knots. This produced conservative estimates of transit time and fuel consumption. However, as a Navy-provided document shows, the Kennedy, for example, can maintain a speed of 28 knots with only five boilers on line and 29 knots with six boilers on line, with sufficient steam to operate the catapults in both cases. We believe that such operations over an extended period of time would be more stressful than normal. However, under these conditions, not all boiler rooms would have to be continually manned and operating. Thus, boilers could be rotated off-line for routine preventive or emergent maintenance. Additionally, the boiler maintenance information DOD provided in response to our request that it amplify its comments indicates substantive scheduled maintenance actions are generally only required at quarterly intervals or longer. While the watch-standing requirements would be greater when only four boilers are operating, carriers are supposed to be manned at a sufficient level that their endurance at a peacetime cruising level of readiness is not constrained.\7 Additionally, Fleet officials familiar with the operation of conventional carriers told us that conventional carriers can operate for extended periods at high speeds. We also noted that they have done so in the past. For example, logs maintained by the Independence during its January/February 1998 transit from Japan to the Arabian Gulf indicated that the ship sailed at 27 knots or faster, generally on six boilers, for over 70 percent of the voyage. The Saratoga, when responding to Iraq's invasion of Kuwait in 1990, sailed at 25 knots or faster for extended intervals again, generally with six boilers on line. As noted elsewhere in this report, this was considered to be the fastest Atlantic Ocean crossing since World War II. 23. We agree that conventionally powered carriers normally refuel when their on-board fuel level reaches 50 percent to 60 percent of capacity. However, the 30-percent minimum fuel level we used is consistent with the provisions of various fleet operating instructions and is greater than that allowed in some instances by those instructions. Therefore, we believe that, in a time of crisis, it is reasonable to expect that reaching the intended theater of operations would have priority over maintaining a high fuel level. 24. For a slightly different perspective, compare the crisis response transits of the U.S.S. Nimitz (CVN-68) and the U.S.S. Independence (CV-62) in late 1997 and early 1998 (see app. IV). 25. We added information on more recent carrier deployments to appendix IV, as noted in comment 3. Further, our independent review of Navy records in some cases differed from the facts the Navy provided. For example, the Navy reported that "In May 1992, EISENHOWER left the Arabian Gulf and transited to the Norwegian Sea steaming 7000 miles at 30 knots average speed. As part of a joint exercise, EISENHOWER sprinted ahead of schedule and launched simulated strikes into northern English air bases earlier than anticipated. The Royal Air Force was taken by complete surprise thinking the battle group was 300-400 miles further south." Our review showed that in May 1992, the U.S.S. Eisenhower was at its homeport of Norfolk, Virginia, having completed a 6-month deployment on April 2, 1992. Navy records also show that the Eisenhower transited the Strait of Hormuz on February 4, 1992, and proceeded to operate in the North Arabian Sea for 10 days before entering the Gulf of Aden on February 15th. The ship operated in the Red Sea for 4 days, spent 3 days in port in Jeddah, Saudi Arabia, then operated in the Red Sea for another 3 days. The ship transited the Suez Canal on February 27, steamed through the Mediterranean, and spent 5 days in port at Palma de Mallorca, Spain. The Eisenhower passed through the Straits of Gibraltar on March 7th and began operating in the exercise in the Norwegian Sea on March 11. The actual period of time for the Eisenhower to travel from the Arabian Gulf to the Norwegian Sea was approximately 35 days. Had the ship averaged 30 knots, it would have covered 7,000 miles in 10.7 days, including a day to transit the Suez Canal. The Navy also said that "On 1 October 1997, NIMITZ was ordered to proceed from the South China Sea (Hong Kong) to the Arabian Gulf at best speed. This 5500 nm transit was completed in 11 days for an average SOA [speed of advance] of about 21 knots. Since NIMITZ was able to conduct flight operations for 6 of the 11 transit days, NIMITZ arrived on station with its airwing fully qualified on 11 October 1997." Our analysis of this transit indicated that the U.S.S. Nimitz averaged 24 knots for the trip. As discussed earlier, the U.S.S. Independence (CV-62) averaged the same speed when it made a similar voyage about 3 months later. The Nimitz spent 30 percent of the voyage at 30 or more knots (38 percent at 27 knots and above), while its longest sustained period of high-speed sailing was 9 hours. In another example, the Navy stated that "In March 1996, the NIMITZ battle group was ordered to move from the Persian Gulf to the western Pacific (Taiwan Straits). The increased self-sustaining capability of a CVN allowed NIMITZ to remain on-station in the Persian Gulf with only one of its (fossil fueled) escorts, while the remaining ships in the battle group began the transit toward east Asian waters. Five days later, NIMITZ departed the Gulf and while en route, refueled her remaining escort and conducted proficiency flight operations prior to overtaking the rest of her battle group as they entered the Taiwan Straits." Our analysis of this transit indicated that ships of the battle group passed through the Strait of Hormuz approximately 40 hours (1.7 days) before the U.S.S. Nimitz and its escort the U.S.S. Port Royal. The Nimitz averaged 19.8 knots for the transit while spending less than 5 percent of the time at speeds of 27 knots and above. The ship sustained speeds of 28-30 knots one time for a 6.5-hour period. In another instance, the Navy stated: "On 23 January 1998, U.S.S. INDEPENDENCE (CV-62) was ordered to transit from Japan to the Arabian Gulf to replace U.S.S. NIMITZ (CVN68), a transit similar to the October 1997 NIMITZ transit. INDEPENDENCE transited 6800 nm with USNS GUADALUPE (TAO 200) at an SOA of about 20 knots, arriving in the Straits of Hormuz on 6 February 1998. INDEPENDENCE did not conduct flight operations en route. Therefore, upon arrival in the Arabian Gulf, INDEPENDENCE required over 3 days of flight operations to qualify her airwing." Our analysis of Navy transit data showed that the U.S.S. Independence averaged over 24 knots for the entire voyage and spent over 70 percent of the time at 27 knots and above. During various parts of the transit, the ship sustained 27 or more knots for several lengthy periods of time, including 42, 31, and 27 hours continuous hours. The U.S.S. Independence refueled three times during the voyage from three separate T-AO-187-class oilers. Since these oilers have a top speed of 20 knots, and the Independence steamed at 27 knots most of the time, it is unlikely that any of the oilers remained with the carrier during the entire voyage. Our review of ship logs and other data indicated that Independence aircraft flew during at least 5 days of the transit, with the last period ending after 11:00 p.m. on February 4th, the night before the ship reached the Strait of Hormuz. Our records indicate that the Independence passed through the Strait of Hormuz shortly before noon on February 5, 1998. 26. We agree that the ability to surge is dictated by the scope and complexity of the maintenance to be performed, which varies from availability to availability. In fact, based on discussions with Navy officials directly responsible for maintenance and actual maintenance data, we found that due to the complexity of its maintenance, a nuclear-powered carrier's maintenance period cannot be shortened to the same degree as that of a conventionally powered carrier. The report provides an example for which the data show that a conventionally powered carrier would require less time to surge from maintenance. We based our analysis on data provided by the Naval Air Force, U.S. Pacific Fleet, and developed by the Navy's aircraft carrier repairs, maintenance, and modernization planning organization. Officials from the Naval Air Force, U. S. Atlantic Fleet reviewed and concurred with the planning organization's information. The data were also provided to the Naval Sea Systems Command's Aircraft Carrier Program Office prior to our receipt. These commands are responsible for coordinating ship maintenance and modernization. Officials from the planning organization noted that a conventionally powered carrier can be brought out of maintenance before all repairs are completed and begin its transit while remaining repairs and maintenance are performed. The nuclear propulsion plants require a more structured approach because of nuclear maintenance requirements and radiological safety concerns. Atlantic Fleet officials stated it would be easier to surge the conventionally powered carrier because additional workers could easily be assigned to complete the work more quickly by completing work tasks in parallel. In contrast, nuclear-powered carrier work is sequential and there are a finite number of nuclear-certified workers. 27. We did not characterize the Persian Gulf War as the definitive wartime scenario. The report states that the nature of Desert Storm--a major regional conflict--portends the types of conflict in which U.S. forces expect to be engaged in the foreseeable future. This statement is based on our assessment of the QDR, Defense Planning Guidance, and other DOD documents that include regional dangers among the threats facing U.S. forces. For example, the QDR, in discussing the regional dangers confronting the United States, states that Southwest Asia--especially Iraq and Iran--is among the foremost threats of coercion and large-scale, cross border aggression by hostile states with significant military power. Furthermore, according to Defense Planning Guidance, "The security environment between now and 2015 will also likely be marked by the absence of a 'global peer competitor' able to challenge the U.S. militarily around the world as the Soviet Union did during the Cold War. . .the U.S. is the world's only superpower today, and it is expected to remain so through at least 2015." We agree with DOD that the United States benefited from a local supply of oil during the Gulf War. However, based on further analysis, we do not believe this was a controlling factor in the outcome of the Gulf War, nor do we believe it would be a significant factor in any of the threats facing the Nation. The Navy has prepositioned large amounts of fuel oil throughout the Central Command, Indian Ocean, and Western Pacific areas. We used the Gulf War scenario to evaluate the effectiveness of conventionally and nuclear-powered carriers in their war-fighting missions because it actually occurred and involved the most extensive and extended combat use of carrier aviation since the Vietnam conflict. 28. We agree that light wind conditions or the necessity to perform downwind air operations can make sortie generation more difficult. However, our review of carrier transit data indicates that conventionally powered carriers, like nuclear-powered carriers, adjust their steaming speeds to meet operational needs. If conditions and operations call for higher speeds, the propulsion plant in the conventionally powered carriers can quickly generate and sustain higher speeds to support flight operations. Throughout this review, we repeatedly sought examples where conventionally powered carriers were unable to meet operational needs. Navy officials provided no examples. 29. We agree that the Naval Sea Systems Command (NAVSEA) letter states that the nuclear propulsion system gives the nuclear-powered carrier an edge. However, its detailed comparisons noted many similarities between various aspects of the two carrier types. Additionally, in discussing this analysis with NAVSEA officials, they told us that neither type of carrier possesses any inherent, overriding advantage over the other in its susceptibility to detection or vulnerability. While there are some differences between the two carriers, neither has a distinct advantage that can be specifically attributed to the ship's propulsion type. These statements support our conclusion that the propulsion system does not materially affect survivability. We also note that DOD's response commented on the CVN-71's and later ships' enhanced survivability to antiship cruise missile attack compared to that of CV-67 and the earlier CVN-68 ships. While engine room fires impair a carrier's mobility, analyses we reviewed discussed a carrier's loss in terms of magazine detonation or sinking due to uncontrollable flooding resulting from blast and fragmentation damage. These analyses indicated that the degree and type of magazine protection incorporated into the ship's design is a greater determinant of survivability than is propulsion and showed that the conventionally powered carrier can have a higher probability of surviving an antiship cruise missile attack than can a nuclear-powered carrier. Furthermore, we continue to believe that while refueling does restrict a carrier's ability to maneuver, the need to replenish will be driven as much by the need to replenish other ships of the battle group as by the carrier. 30. We disagree that a new design conventionally powered carrier would necessarily result in a larger and heavier ship, as discussed in comment 1. 31. Increases in fleet oiler requirements because of conventional propulsion in carriers may not be as great as postulated because, in general, infrastructure requirements are seldom increased or decreased in response to small changes in force structure. A 1992 Center For Naval Analyses report on Combat Logistics Force ship requirements for battle forces centered around conventionally or nuclear-powered carriers concluded that nuclear propulsion for carriers alone had only a marginal effect on the number of support ships needed to sustain battle forces in a typical combat scenario. The scenario postulated a naval deployment to a limited regional conflict in Southwest Asia with naval forces supported from bases in the Western Pacific. This scenario was chosen because the extreme distances involved would tend to highlight the differences between the numbers of Combat Logistics Force ships needed to support battle groups with nuclear-powered carriers and battle groups with conventionally powered carriers. The report also found that on an individual basis, a conventionally powered carrier needs only one-half more of an oiler than a nuclear-powered carrier used in a similar fashion (or, for a force of 12 carriers, an additional 6 fleet oilers). The report noted that earlier studies of Combat Logistics Force requirements used much higher estimates for ship propulsion fuel. This fact may contribute to the view that the nuclear-powered carrier offers a freedom from oilers not possible with conventionally powered carriers. The report also noted that, in practice, carriers, regardless of propulsion type, are replenished whenever operational demands make it possible, typically during rest periods between major flight operations, which normally occur every few days. As we note in appendix V, the Center for Naval Analyses concluded that the "increased capacity for ordnance and aviation fuel in the CVN [nuclear-powered carrier] design is not sufficient to untether the force from the [logistic] pipeline. The hoped for increase in freedom of operational employment for CVNs is further restricted by the fossil-fuel dependence of the accompanying surface combatants." Another important factor that could affect the ultimate size of the oiler infrastructure is the Navy's general need for a global array of fuel replenishment ships and depots. We note that the Navy requires a worldwide supply system because the ship battle force is mostly a conventionally powered ship force (253 of 349 ships as of April 14, 1998).\8 Appendix III shows that escort ships of a conventionally powered carrier battle group generally needed from two-thirds to three-quarters of the total battle group's overall underway replenishment fuel requirement. 32. In response to our requests, DOD provided no specific examples where a conventionally powered carrier's inability to accelerate actually caused the situations it mentioned to occur. As stated in the report, ship personnel are aware of wind conditions during flight operations and can adjust the ship's speed, as necessary, to respond to varying landing conditions in a timely manner. Our review of data gathered during specific ship transits revealed numerous examples where dramatic speed and directional changes were made by conventionally powered carriers in short periods of time to respond to operational needs. We identified two instances during the recent high-speed transit of the U.S.S. Independence (CV-62) from Japan to the Persian Gulf where aircraft experienced single-engine emergencies. With the exception of a minor speed change in one instance, no other speed or directional changes were made, and both aircraft were recovered safely. 33. Our estimate did not include an allocation of acquisition cost of the fuel delivery costs because we did not have comparable acquisition cost data for facilities (i.e., Department of Energy (DOE) laboratories) that supported the delivery of nuclear power to the Navy's fleet. We view these as sunk costs because they tend to be invariant with the size and mix of the forces. We excluded acquisition costs for all supporting activities and functions whether they supported conventionally or nuclear-powered carriers or both types of carriers. 34. Our pipeline training cost estimate is greater because it includes a more complete universe of costs that are required to provide a steady supply of trained nuclear propulsion plant personnel. In its comments, the Navy estimates training pipeline costs at about $13.4 million, which is based on an allocation of the $142 million it spends annually on nuclear training. However, budget data indicate that the Navy spends nearly $195 million annually for student, instructor, operations, and support personnel and over $80 million in operations and maintenance funds for its moored ships; the latter amount does not include operations and maintenance funds for classroom training at the Nuclear Power School. Our estimate was based on applying the annual per student training cost, which includes all applicable personnel and operations and maintenance costs, to the estimated annual training requirement to support one nuclear-powered carrier. 35. We allocated the cost of DOE's nuclear support activities based on the benefit received by the nuclear-powered ships. Since the purpose of the Naval Nuclear Propulsion Program is to ensure safe and efficient production of energy, we allocated the program costs according to the amount of energy consumed. This methodology is in accordance with The Federal Accounting Standards Advisory Board (FASAB), which recommends that indirect costs be assigned or allocated based on the consumption or demand for the activity. Moreover, several DOE and Navy officials suggested this was the best allocation methodology. This methodology is also consistent with the way fossil fuel support activities are allocated based on fuel usage. We overstated the costs for nuclear support activities in our draft report, but we adjusted these costs in the final report. 36. Our carrier disposal costs are based on an estimate provided by the Navy in fiscal year 1994 and updated in fiscal year 1996. In its comments, DOD provided a new estimate for the inactivation and disposal costs of a Nimitz-class carrier. We did not use the newer estimate, which was about 40 percent less than the 1996 estimate, because the Navy did not provide any evidence that would support significant changes to the 1996 estimate. Most of the reductions in its new estimate are attributed to a large learning curve and to new technologies. Officials from the Navy's principal shipyard for nuclear plant inactivation and disposal, the Navy's carrier maintenance experts, and the cost estimating community have told us that it is highly unlikely that any significant cost reductions can be obtained from learning in an episodic activity such as the refueling or inactivations of a Nimitz-class carrier. Large scale activities such as these with intervals of about 4 years do not lend themselves to learning curve reductions on the scale that is included in DOD's new estimate. Further, over the past 20 years, the methods and technologies have remained fairly constant. The Navy was unable to provide any examples of technologies that could result in potential cost reductions ranging from 20 to 40 percent. Moreover, according to a recent Navy report, ¹although delaying disposal could potentially allow the development of some new technology to deal with the disposal of radioactivity, there is nothing presently on the horizon that would hold the promise of a more cost effective, environmentally safe disposal method for reactor departments.º\9 37. In our draft report, our estimate for spent nuclear fuel (SNF) was based on a "wet storage" method. The Navy told us that it plans to store SNF using a different method referred to as dry storage. We modified the report accordingly. -------------------- \1 This capability is a computer-based system that permits simultaneous sharing of detailed targeting data between ships or forces at extensive ranges within the littoral area, thereby increasing reaction time and firing opportunities against enemy missile attacks. \2 Chief of Naval Operations. OPNAV Notice 4700, Subject: Notional Intervals, Durations, Maintenance Cycles, and Repair Mandays for Depot Level Maintenance Availabilities of U.S. Navy Ships. \3 According to data DOD provided to us on April 2, 1998, Commander Logistics Group Two assumed a 26-knot or higher transit for 10 days, with the transferable propulsion fuel capacity from an AOE-6 class ship (2.1-4.0 million gallons of DFM). \4 See app. I for a more detailed explanation of our methodology for calculating the availabilities. \5 Ship Self Defense: Program Priorities Are Questionable (GAO/NSIAD-97-195R, Aug. 15, 1997). \6 Statement of Admiral Archie Clemins, U.S. Navy, Commander in Chief, U.S. Pacific Fleet, before the Subcommittee on Readiness, House Committee on National Security, Mar. 6, 1998. \7 The document discussing the required operating capabilities of the aircraft carriers specifies four readiness conditions for a carrier that is underway. These range from Condition I: Battle Readiness to Condition IV: Peacetime Cruising Readiness. Our review of several extended transits indicates that the carriers generally steam at Condition IV. \8 The Ship Battle Forces consists of Battle Forces, Mobilization Forces, Category A Assets, Strategic Forces and Support Forces. The Battle Forces include aircraft carriers, surface combatants, submarines, amphibious warfare ships and mine warfare ships in an active status. Combat logistics ships, both active and those under the Military Sealift Command (MSC) and Naval Fleet Auxiliary Force, are also included. \9 Department of the Navy. Final Environmental Impact Statement on the Disposal of Decommissioned, Defueled Cruiser, Ohio Class, and Los Angeles Class Naval Reactor Plants (April 1996).