United States General Accounting Office Washington, D.C. 20648 National Security and International Affairs Division B-257746 July II,1994 The Honorable Sam Nunn Chairman, Committee on Armed Services United States Senate The Honorable Strom Thurmond Ranking Minority Member Committee on Armed Services United States Senate The Honorable Ronald V. Dellums Chairman, Committee on Armed Services House of Representatives The Honorable Floyd Spence Ranking Minority Member Committee on Armed Services House of Representatives The fiscal year 1994 conference report on the Department of Defense’s (DOD) Authorization Act requires that we monitor the cost, schedule, and performance of the C-17 program and report to the House and Senate Committees on Armed Services. Since the Air Force considers the G17’s ability to land at substantially more airfields than the C-5 crucial, we are providing our analysis of the number of airfields that will be available to the C-17 compared to what is available to the C-5. The Air Force has reported that based on wartime runway length and width requirements, the C-17’sc apability to land on short airfields would enable it to land at about 9,900 Melds in the free world (less the United States) compared to 3,500 for the C-5. However, this estimate did not take into account runway strength and included all types of airfields, ranging from concrete and asphalt to gravel, dirt, and grass, many of which are not suitable for either aircraft. When wartime landing requirements, including minimum runway strength, are considered, the C-17’sw artime airfield advantage decreases from 6,400 to about 900 tields.’ ‘The 6,400 figure excluded airfields in the United States. The 900 figure excluded airfields in North America However, the effect is minimal. Page 1 GAO/NSIAD-94-225 Military Airlift B-267746 The C-17 advantage is further reduced when only airfields that have been determined by the Air Force to be suitable for military operations are considered. To date, the Air Force has surveyed about 2,800 airfields worldwide as suitable for military operations. When wartime landing requirements, including minimum runway strength, are considered, the C-17’sw artime airfield advantage is 145. When airfields in the United States, Canada, and Mexico are excluded, the C-17’sw artime advantage decreases to 95 airfields. Although DOD and the Air Force have claimed that the C-17’sc apability to land at small, austere airfields during contingencies provides significant military advantage, DOD’S 1992 Mobility Requirements Study identified only three such airfields that would be used by the C-17 in the major regional contingency scenarios, Two are located in Korea and one in Saudi Arabia In discussing the issues raised in this report, Air Force officials stated that the number of airfields that will be available to the C-17, but are not available to the C-5, is not as great as previously reported. Further, these officials stated that the Mobility Requirements Study is based on current rnihtary doctrine that does not reflect the use of small, austere airfields and that when the C-17 is fuhy operational, the Army will change its doctrine accordingly. Army officials told us they will not begin to plan for the aircraft’s capability until it is fully operational. Air Force officials also told us the Mobility Requirements Study did not reflect the use of small, austere airfields since this capability is not a major factor in the southwest Asia or Korean scenarios. Comparison of C-17 Over the years, there has been considerable debate concerning the number of airfields on which the C-5 and the C-17 can land. The C-17 Operational and C-5 Airfield Requirements Document specifies a wartime landing performance Availability capability of landing on a 3,000-foot long by 9@foot wide paved runway. According to an Air Force official, all G17 pilots will be trained for the wartime performance landing capability. Normal landing performance is defined as safe and routine landings on a paved runway 4,000 feet long by E 90 feet wide. The Air Force restricts the C-5 to runways 5,000 feet long by 90 feet wide E during wartime. However, Air Force officials believe this criteria is unrealistic since C-5 pilots are not trained to land on runways smaller than / 5,000 feet long and 150 feet wide. They said that 131 feet is the narrowest runway the C-5 has landed on during wartime. Normal landing Page 2 GAO/NSIAD-94-225 Military Airlift B-267746 performance is defined as landing on a paved runway 6,000 feet long by 147 feet wide. In 19862a nd 1991: the Air Force reported that the C-17 would be able to land on three times as many airfields as the C-5, or 9,900 compared to 3,500 for the C-5, a 6,400~airfielda dvantage for the C-17. These estimates were using wartime landing requirements where the C-17 would land on runways at least 3,000 by 90 feet and the C-5 would land on runways at least 5,000 by 90 feet. However, these estimates did not consider runway strength and included all types of runways ranging from concrete and asphalt to gravel, dirt, and grass, many of which are not suitable for either airplane. Runway Strength Affects Whether an aircraft can land on an airfield depends upon a number of Airfield Suitability factors, including runway length, width, and strength or load classification number (EN). LCN is a number ranging from 1 to 120 and represents the strength of the runway.4 The higher an LCN, the stronger the runway. Aircraft also have designated LCNS. Aircraft with higher LCNS should land on stronger runways. The C-17 is more limited in this respect than the C-5. The C-17’sL CN is 48, whereas the C-5’sL CN is 32. The Defense Mapping Agency classifies LCNS into broad categories called load classification groups (LCG). An LCG of I includes LCNS from 101t o 120. An LCG of II includes LCNS from 76 to 100.A t maximum payload, both the C-17 and the C-5 fall into LCG IV, which includes LCNS from 3 1 to 50. According to Defense Mapping Agency officials, a C-17 or C-5 could make unlimited landings on an LCG IV-type runway and should not damage the airfield. It is not clear whether LCN or LCG should be used to determine aircraft landing requirements. The C-17 contract requires the aircraft to land on paved runways with an LCN of 48. However, the C-17 Operational Requirements Document calls for it to land on runways rated as LCG IV. When LCG IV criteria is used to determine airfield suitability, the number of airfields that the C-17 can land at increases because weaker runways, those with LCNS ranging from 31 to 47, also become available. %e Casef or the Cl7 the Operators’sV iew (1986). 3Airlift and US. National Security: the Casef or the C-17 (1991). ‘LCN quantifies the relative strain placed on a runway by different types of aircraft operating at differentweightsandtire pressuresandwithdifferingnumber ofwheels. Page 3 GAONSIAD-94-225 Military Airlift B-257746 According to Air Force officials, LCN is a peacetime design criteria, and wartime airfield access is not based on peacetime criteria We were told that an LCN of 20 should be used when assessing airfields for use during wartime. Based on this criteria, a C-17 or C-5 could land on a runway with an LCN of 20 about 100 times before severely damaging it. Comparison of Airfield Using recent Defense Mapping Agency data and excluding airfields in the Access United States, Canada, Mexico, and Central America,6 we compared airfield availability worldwide for the C-17 and C-5 based on wartime landing requirements, including runway strength. When an LCN of 20 is used as criteria for runway strength, the C-17’s airfield advantage decreases significantly. As shown in figure 1, according to Defense Mapping Agency data, the C-17 can land at 3,702 airfields compared to 2,791 for the C-5. According to the Air Force’s reported numbers, the C-17 can land at 9,900 airfields and the C-5 at 3,500. Thus, the C-17’sa irfield advantage decreases from 6,400 to 911 under wartime conditions. While this represents the number of potentially suitable melds, before actually using one of these airfields, other factors such as runway obstructions would have to be taken into account. As a result, the actual number of airfields accessible to either aircraft is probably somewhat less than shown in figure 1. @I’heD efense Mapping Agency identified airfields by continent As such, airfields within Central America are included in the North America totals and cannot be separately identified. Page 4 GAO/‘NSIAD-94-226 Mllitary AtrliPt B-257746 Figure 1: Impact of Runway Strength on Airfields Available to C-17 and C-5 Number of airfields Considering Not considering airfield strength airfield strength Note: The C-5’s wartime criteria is 5,000 by 90 feet, and the C-17’s wartime criteria is 3,000 by 90 feel. Using a runway width of 131 feet, the width that Air Force officials have told us is the narrowest runway that the C-5 has actually landed on during wartime, results in a C-17 advantage of about 1,400a irfields. Airfield Availability Based The C-l 7’sa irfield advantage is also less than previously reported when on Operational runway availability is based on LCG and type of surface. According to the Requirements C-17 Operational Requirements Document, the C-17 must be able to land on a paved airfield 3,000 feet long by 90 feet wide with an I-IV. Using LCG this criteria, the C-17 could land at 2,404 airfields. The C-5 landing with the similar criteria could land at 2,153 airfields 5,000 by 90 feet wide and 1,896 Melds 5,000b y 131 feet wide. The C-17, therefore, has only a 251-airfield advantage worldwide when the published runway criteria is used and a Page 5 GAo/NsrAD-94-226 Bulitary Airlift B-257746 5OELadvantagwe hen the Air Force modified criteria is used. Figure 2 compares C-17 and C-5 airheld availability based on wartime landing requirements USiIIgdowableLCGs. and C-5 (LCG I-IV) Number of airfields 1500 1000 500 0 T-5: 5,000 x 90 feet bC-5: 5,000 x 131 feet “C-17: 3,000 x 90 feet Fewer Airfields The number of airfields surveyed by the Air Mobility Command and identified as suitable for military airlift is about 7,100l ess than the Determined Suitable approximately 9,900 airfields identified by Air Force using Defense for Military Missions Mapping Agency data. The Airfield Suitability Report, prepared by the Air Mobility Command, lists 2,783 airfields worldwide that have been analyzed to date for their suitability for military operations. Besides runway length and width, the Air Mobility Command assessesa irfield suitability for each airlift aircraft based on runway strength, entry and exit, taxiways, parking, and obstructions. Page 6 GAO/NSIAD-94-226 Military Airlift E-257746 Airfield Availability Based Our analysis of the Airfield Suitability Report data using wartime landing on Airfield Suitability requirements shows that the C-17 has little or no airfield advantage in many countries. Figure 3 shows that the C-17’sa irheld advantage over the C-5 is greatest in the United States, Canada, Japan, Colombia, and Germany. In Korea, the C-17’sa irfield advantage is six and in Saudi Arabia the advantage is limited to one airfield. In total, the C-17’sa irfield advantage over the C-5 amounts to 145. When airfields in the United States, Canada, and Mexico are excluded, the C-17’sa irfield advantage over the C-5 is 95 airfields. We found that 830 of the 2,783 airfields in the Airtleld Suitability Report are in countries where the C-17 had no advantage. That is, both the G5 and C-17 could land at an equivalent number of airfIelds. Further, we identified 585 and 440 of the 2,783 airfields that did not meet C-5 and C-17 wartime landing requirements, respectively. Appendix I provides a listing of those countries where the C-17 has an airfield advantage. Air Force officials told us that the Airfield Suitability Report is a conservative estimate of airfields available to the C-17. They stated that airfields are only surveyed for suitability upon request; thus, when the C-17 a becomes fully operational, the number of suitable airfields may increase. Page 7 GAO/NSIAD-94-226 Wlltary Airlift United Kingdom i Ii i Belgiut i ~ $,,Bahamas Pan co10 b Advantage for C-17 pgpj _ . 1 ;F,<: a& 1 5 Atrffelds 6-10 Airfields -3 11m30 Airfields & I 1 Page 8 GAODMAD-94-226 Military Airlift i