NAVY AIRCRAFT CARRIERS  - GAO/NSIAD-98-1 - August 1998 NAVY AIRCRAFT CARRIERS
Cost-Effectiveness of Conventionally and Nuclear-Powered Aircraft Carriers
GAO/NSIAD-98-1 -- August 1998

MISSIONS GENERATED BY EACH CARRIER WERE COMPARABLE FOR THE REGIONS IN WHICH THEY OPERATED --------------------------------------------------------- Appendix V:1 When Operation Desert Storm began on January 17, 1991, the Navy had three conventional carriers, U.S.S. America (CV-66), U.S.S. John F. Kennedy (CV-67), and U.S.S. Saratoga (CV-60), positioned in the Red Sea and two conventional carriers, U.S.S. Midway (CV-41) and U.S.S. Ranger (CV-61), in the Persian Gulf. The nuclear-powered U.S.S. Theodore Roosevelt (CVN-71), sailing from the Red Sea to the Persian Gulf when hostilities began, did not begin to strike targets until January 22nd. The Navy operated three carriers each in the Red Sea and Persian Gulf for about 3 weeks until the America moved to the Persian Gulf in mid-February 1991, shifting the number of carriers in each operating area to two and four ships, respectively. Navy fixed-wing carrier-based aircraft flew over 18,000 sorties during the war, according to statistics developed by Center for Naval Analyses in an analysis of Desert Storm carrier operations. Aircraft from the Red Sea Battle Force flew nearly 6,200 sorties (one-third of the sorties), while aircraft from the Persian Gulf Battle Force flew nearly 11,800 sorties. We believe that the significant differences in the operations of the two battle forces were largely driven by the ranges to their targets. The Red Sea carriers were about 400 to 600 nautical miles away from their targets. Their aircraft had to fly even greater distances to get to and from aerial tanker positions and to use specific entry and exit corridors to reach the targets. The Persian Gulf carriers, on the other hand, launched many missions to the coastal region and were generally closer to their targets than the Red Sea carriers. As a result, the Persian Gulf carriers generally launched more sorties of shorter duration. As the war progressed, the Persian Gulf carriers moved further north in the Gulf, reducing strike ranges even more. The shorter distances allowed the carriers to shift into cyclic operations and generate many more sorties in the same span of time. In addition, the America's move to the Persian Gulf increased the number of carriers to four and added further to the total sorties generated by those carriers. Because of the extended ranges involved during attacks on Iraq, carrier-based aircraft required refueling from land-based tankers. Aircraft from the Red Sea carriers relied on land-based tankers for the duration of the war. In the Persian Gulf, the carriers were initially positioned about 280 nautical miles southeast of Kuwait City. As the war progressed and the threat of Iraqi air and missile attacks on the Persian Gulf carriers diminished, the carriers moved farther north, reducing their dependence on land-based tankers. By the start of the ground war in late February, the carriers were positioned about 185 nautical miles southeast of Kuwait City. After the carriers' arrival in the northernmost operating areas, Navy refueling aircraft provided all refueling for Persian Gulf naval air strikes. The total sorties generated by each carrier, as well as the average number of sorties flown during the war, are shown in table V.1. The Kennedy and the Saratoga operated in the Red Sea during the entire period, while the Midway, the Ranger, and the Roosevelt operated in the Persian Gulf. The America began the war in the Red Sea but moved to the Persian Gulf in mid-February for the final stages of the war. Table V.1 Average Sorties Per Day Per Carrier During Desert Storm (43 days) Sarato Roosev Midway ga Ranger Americ Kenned elt (CV- (CV- (CV9- a (CV- y (CV- (CV- 41) 60) 61) 66) 67) 71) Total ------------------------ ------ ------ ------ ------ ------ ------ ------ Total sorties 3,019 2,374 3,329 2,672 2,574 4,149 18,117 ================================================================================ Daily average 70.2 55.2 77.4 62.1 59.9 96.5 421.3 -------------------------------------------------------------------------------- Source: Our analysis of Center for Naval Analyses data. NUMBER OF SORTIES GENERATED BY INDIVIDUAL CARRIERS WERE PROPORTIONAL TO THE SIZE OF THEIR AIR WINGS --------------------------------------------------------- Appendix V:2 The number of aircraft assigned to each carrier varied considerably and had a direct impact on the sorties generated by each carrier. When the average number of sorties per assigned aircraft are compared, there is little difference between carriers operating in the same area (see table V.2). Although the U.S.S. Theodore Roosevelt (CVN-71) launched the most sorties of any carrier (4,149), the ship, along with the U.S.S. John F. Kennedy (CV-67), had the most aircraft assigned--78 aboard each carrier. Since the Roosevelt operated in the Persian Gulf, considerably closer to assigned targets than the Kennedy in the Red Sea, it was able to generate more sorties. On the other end of the spectrum, the World War II-vintage U.S.S. Midway (CV-41) had only 56 aircraft assigned (nearly 30 percent less than the Roosevelt), the least of any carrier, followed by the U.S.S. Ranger (CV-61) with 62 aircraft. When sorties are compared based on the number of aircraft assigned, the sortie generation rates are nearly identical between the carriers. The significant differences are between the Red Sea and Persian Gulf carriers. When carriers in the same region are compared, their sortie generation rates are also almost identical. The Kennedy and the U.S.S. Saratoga (CV-60), which operated in the Red Sea for all of Desert Storm, each averaged 33 sorties per aircraft. The three full-time Persian Gulf carriers, Midway, Ranger, and Roosevelt, each averaged about 53 sorties per aircraft. Table V.2 Comparison of the Average Number of Sorties Generated By Each Carrier Midway Saratoga Ranger America Kennedy Roosevelt Tota (CV-41) (CV-60) (CV-61) (CV-66) (CV-67) (CVN-71) l -- ---------- ---------- ---------- ---------- ---------- ---------- ==== ================================================================================ To 3,019 2,374 3,329 2,672 2,574 4,149 18,1 t 17 a l s o r t i e s Aircraft assigned: -------------------------------------------------------------------------------- F- 0 20 20 20 20 20 100 14 F/ 30 18 0 18 0 19 85 A- 1 8 A- 14 14 22 14 13 18 95 6E A- 0 0 0 0 24 0 24 7 E- 4 4 4 4 5 4 25 2 EA 4 4 4 5 5 5 27 - 6 B KA 4 4 4 4 3 4 23 - 6 D S- 0 8 8 8 8 8 40 3B ================================================================================ To 56 72 62 73 78 78 419 t a l ================================================================================ Av 53.9 33.0 53.7 36.6 33.0 53.2 43.2 e r a g e s o r t i e s p e r a i r c r a f t -------------------------------------------------------------------------------- Source: Our analysis of Center for Naval Analyses data. CARRIERS OPERATED ON A ROTATING BASIS --------------------------------------------------------- Appendix V:3 Although Navy aircraft flew sorties every day throughout Desert Storm, none of the carriers operated around-the-clock. Instead, they rotated on an operating schedule that enabled them to have intervals of off-duty time. According to the Center for Naval Analyses data, the three carriers initially operating in the Red Sea, the U.S.S. America (CV-66), the U.S.S. John F. Kennedy (CV-67), and the U.S.S. Saratoga (CV-60), followed a rotating schedule with two carriers conducting flight operations while the third stood down for 2 days. When the America departed for the Persian Gulf on February 7th, the remaining two carriers continued to operate with periodic stand-down intervals. In the Persian Gulf, the U.S.S. Midway (CV-41), the U.S.S. Ranger (CV-61), and the U.S.S. Theodore Roosevelt (CVN-71) also followed a rotating operating schedule. Each carrier conducted air operations for approximately 15 hours during a 24-hour interval. During the remaining 9 hours of a 24-hour interval, one carrier suspended air operations. The Ranger's and Roosevelt's on-duty periods occurred during opposite portions of the 24-hour interval--with 3 hours of concurrent operations during turnovers. The Midway's on-duty period was roughly centered on one of Ranger's and Roosevelt's turnovers. The Center for Naval Analyses reported that there were only 6 days during the war when all six carriers operated. The rest of the time usually four or five carriers were on line while others stood down. AVERAGE SORTIES PER OPERATING DAY WERE NOT SIGNIFICANTLY DIFFERENT AMONG THE CARRIERS --------------------------------------------------------- Appendix V:4 When daily sortie rates were based on the number of days each carrier operated, there was a significant increase in average sorties. As shown in table V.3, the U.S.S. Theodore Roosevelt (CVN-71) led all carriers, averaging about 106 sorties per day. The smallest and oldest carrier, the U.S.S. Midway (CV-41), averaged about 89 sorties, 17 less than the Roosevelt, but did so with 22 fewer aircraft. When we factored in the number of assigned aircraft to average number of sorties per operating day, the Midway led all carriers. The Midway averaged 1.59 sorties per aircraft per operating day, followed by the U.S.S. Ranger (CV-61) with an average of 1.41 sorties, and the Roosevelt with 1.36 sorties. Table V.3 Average Sorties Per Operating Day Generated By Each Carrier Midwa Sarato Range Ameri Kenned Roosev y ga r ca y elt (CV- (CV- (CV- (CV- (CV- (CVN- 41) 60) 61) 66) 67) 71) ------------------------- ----- ------ ----- ----- ------ ------ Total sorties 3,019 2,374 3,329 2,672 2,574 4,149 Aircraft assigned 56 72 62 73 78 78 Operating days 34 33 38 31 31 39 Average sorties per 88.8 71.9 87.6 86.2 83.0 106.4 operating day ====================================================================== Average operating day 1.59 1.00 1.41 1.18 1.07 1.36 sorties per aircraft ---------------------------------------------------------------------- Source: Our analysis of Center for Naval Analyses data. LOGISTICS SUPPORT WAS COMPARABLE FOR ALL CARRIERS --------------------------------------------------------- Appendix V:5 The Navy committed about 40 percent of its Combat Logistics Force ships--combat stores ships, oilers, ammunition supply ships, and multicommodity fast combat support ships--to Desert Storm. Each of the carrier battle groups was assigned its own dedicated support ships, to the extent possible, that remained on station with its battle group and enabled frequent replenishment of fuel and ordnance. According to Center for Naval Analyses, all carriers were replenished at about the same frequency, approximately every 3 to 3-1/2 days. The Center for Naval Analyses concluded that the increased capacity for ordnance and aviation fuel in the nuclear design was not sufficient to untether the battle force from the logistics pipeline. It also concluded that the hoped for increase in freedom of operational employment for nuclear carriers was restricted by the fossil fuel dependence of their accompanying surface combatants. FUEL REPLENISHMENT DURING DESERT STORM WAS COMPARABLE FOR NUCLEAR- AND CONVENTIONALLY POWERED CARRIERS --------------------------------------------------------- Appendix V:6 According to the Center for Naval Analyses, which published several studies related to Desert Storm, the frequency that aviation fuel was replenished was essentially the same for all carriers, including the U.S.S. Theodore Roosevelt (CVN-71), even though nuclear-powered carriers have about 1.7 million more gallons of aviation fuel storage capacity. Table V.4 shows that aviation fuel was replenished about every 3 days for the carriers operating in the Persian Gulf. Table V.4 Frequency of Aviation Fuel Replenishment by Persian Gulf Carriers During January and February 1991 Roosev Midway Ranger Americ elt (CV- (CV- a (CV- (CVN- 41) 61) 66) 71) -------------------------------------- ------ ------ ------ ------ Number of replenishments 19 41 6 12 Days in Persian Gulf 59 46 16 40 Replenishment frequency (days) 3.1 3.1 2.7 3.3 ---------------------------------------------------------------------- Source: Our analysis of Center for Naval Analyses data. Similarly, in the Red Sea, the conventionally powered carriers operating also received aviation fuel every 2 to 3 days. The Center for Naval Analyses stated that, ¹In practice, ships are topped-off whenever other operational demands make it possible.º It reported that from February 17-27, 1991, the peak period of the air campaign, aircraft from the Roosevelt consumed an average of over 4,930 barrels (207,060 gallons) of fuel daily, while U.S.S. America (CV-66) aircraft consumed about 4,990 barrels (209,580 gallons) daily. The amount of aviation fuel consumed daily represented only a small percentage of each carrier's JP-5 capacity. ORDNANCE WAS ALSO REPLENISHED FREQUENTLY --------------------------------------------------------- Appendix V:7 According to Center for Naval Analyses, ordnance expenditures by the Persian Gulf carriers averaged about 49 tons per day per carrier during the entire war. This rate increased to 116 tons per day during the 4-day ground offensive. Each Red Sea carrier averaged about 43 tons per day during the war and 59 tons per day during the ground war. The smaller Red Sea expenditure rates were probably due to the smaller number of sorties flown as a result of the longer distances these aircraft had to fly to reach their targets. Like fuel, ordnance was also replenished about every 3 days for the Persian Gulf carriers and about every 1 to 2 days in the Red Sea, even though the ordnance expended over a 2- to 3-day period was only a fraction of the ships' storage capacities. For example, according to Center for Naval Analyses, the U.S.S. Theodore Roosevelt (CVN-71) was rearmed seven times during the last 20 days of February 1991, receiving over 1,600 tons of ordnance. During this period, the Roosevelt expended an average of about 2 percent of the capacity (by weight) per day. The U.S.S. Ranger (CV-61) was also rearmed seven times over this interval, even though only about 5 percent of its ordnance capacity was consumed daily. Similarly, the U.S.S. Midway (CV-41) was rearmed nine times between January 16 and February 16, 1991, even though only about 5 percent of its ordnance capacity was expended daily.