According to DOD, there were 287 aircraft in the OSA fleet as of May 2017. All OSA aircraft are military variants of commercial aircraft. (See appendix IV for more information and images of these aircraft.) Table 1 lists the number of OSA aircraft by DOD owner/operator and type of usage. A majority of the executive aircraft is located at Joint Base Andrews, Maryland, and a small number are located overseas, as shown in table 2. Thirteen of the 44 executive aircraft are designated as service secretary controlled aircraft. The primary mission for these 13 aircraft is to transport the military departments' Secretaries, Chiefs of Staff, and other senior officials such as the Undersecretaries and Vice Chiefs of Staff. Service secretary controlled aircraft also support travel for members of congress and for White House support missions, including for cabinet-level officials. In addition, 9 of the 44 executive aircraft are designated for use by the Commanders of the Combatant Commands. As of May 2017, the Army owned and operated 121 of the 243 nonexecutive aircraft. U.S. Africa Command leased one aircraft, and the remaining 121 aircraft belonged to the U.S. Special Operations Command, Marine Corps, Navy, and Air Force, which respectively owned 21, 25, 33, and 42 aircraft. Of the Air Forces' 42 nonexecutive aircraft, 18 were designated for Defense Intelligence Agency or Defense Security Cooperation Agency support to overseas locations. Multiple officials have responsibilities for approving the use of government aircraft and air travel. Specifically, the Secretaries of the Military Departments, the Chairman of the Joint Chiefs of Staff, and Combatant Commanders review and approve requests within their respective commands. In addition, the Office of the Secretary of Defense Executive Secretary and the Assistant Secretary of Defense for Legislative Affairs prioritize and approve requests within their approval authorities. Table 3 summarizes the responsibilities for approving requests for use of government aircraft. DOD guidance sets clear priorities for the use of its aircraft to support officials in certain positions within the department. Specifically, the guidance lists 26 required DOD users and 35 authorized DOD users of government aircraft who are categorized into four tiers. DOD's highest priority (tier one) travelers are required to use government aircraft for both official and unofficial travel while tier two travelers are required to use government aircraft only for official travel. The Secretary of Defense prioritizes tier one and tier two officials as travelers that are required to use government aircraft because there is a continuous requirement for secure communications; a threat exists that could endanger lives; or there is a need to satisfy exceptional scheduling requirements that make commercial transportation unacceptable. DOD's tier three and four travelers are not required to use government aircraft, but are authorized to use the aircraft for official travel when the demands of their travel prevent the use of commercial aircraft. DOD's aircraft are also used to support employees and members of Congress and White House support missions--a user pool which could total over 550 users. Table 4 lists the required and authorized users of DOD's aircraft. White House support missions are trips provided by DOD and directed by the President such as travel for cabinet-level officials, the Vice-President, and First Lady. DOD guidance supports travel for members and employees of Congress when approved by the Assistant Secretary of Defense for Legislative Affairs. DOD supports travel for congressional users when the purpose of travel is related to DOD programs or activities. DOD guidance does not support travel for congressional users if a commercial flight is able to meet the users' departure and arrival requirements within a 24-hour period. However, if the trip includes unusual circumstances, such as a clear and present danger or other compelling operational considerations that make commercial transportation unacceptable, then congressional users may use military aircraft. During calendar years 2014 through 2015, government and military officials took more than 19,000 flights on OSA executive aircraft, and our review of a nongeneralizable, random sample of flight packages from calendar years 2014 and 2015 found that DOD generally followed its guidance for approving use of these aircraft for these selected flights. We analyzed the data for executive flights conducted during calendars years 2014 and 2015, and found that there were a total of 19,752 flights. In both calendar years most of the flights were flown by authorized, but not required users, as shown in Table 5. During calendar years 2014 and 2015, DOD's four tier one required users accounted for 4 percent of the total executive flights. Its 22 required tier two users accounted for another 27 percent of the total. The remaining 69 percent of the flights were taken by the hundreds of personnel who were authorized, but not required, to use DOD's executive aircraft. As indicated in table 5, 29 percent of the total executive flight data was categorized in non-specific terms such as "below tier 2 user". Consequently, it is not possible to provide exact percentages of flight usage for each of the different authorized user categorizes. However, based on the 2014 and 2015 authorized user flight data that was specifically categorized, the following users accounted for at least these percentage of the total flights: tier-three users, 21 percent; tier-four users, 1 percent; White House support mission users, 12 percent; and Congressional delegations, 5 percent. According to DOD officials, most of the non-specific flights were for tier-three-and-four users, but some of the flights were for White House support missions or Congressional delegations. Additional analyses of the calendar year 2014 and 2015 flight data showed that usage rates varied both within and across months and years. For example, in calendar year 2014, the number of daily flights ranged from a low of 2 flights on December 30, 2014, to a high of 70 flights on December 8, 2014. In calendar year 2015, the low ranged from 2 flights on April 5, 2015, to a high of 51 flights on December 18, 2015, and March 31, 2015. During calendar years 2014 and 2015, the executive flights went to over 1,000 locations, and the ten most visited destinations accounted for about 40 percent of those flights. Those locations included Joint Base Andrews in Maryland; Ramstein Air Base in Germany; MacDill Air Force Base in Florida; Scott Air Force Base in Illinois; and Stuttgart Airport in Germany. DOD officials told us that they often see high demand for executive aircraft to support congressional users during congressional recess periods. We found that users in all categories, including congressional, White House support missions, as well as required DOD, and all other authorized users, flew on most days during the 2014 and 2015 two-week spring and four to five-week summer congressional recess periods. However, when we analyzed the total numbers of daily flights, we found that most of days with 40 or more executive flights occurred outside the congressional recess period in calendar year 2014 or 2015, and only one day--during the 2015 spring recess, occurred within those periods. In total, during calendar year 2014, there were 71 days where OSA aircraft flew 40 or more flights, and in 2015 there were 23 days with 40 or more flights. DOD officials told us that they generally prioritize White House support missions and congressional users over tier three or four authorized users. However, at times they are unable to accommodate congressional travelers due to number of participants and distance of travel requirements. DOD officials stated that congressional requests often include larger participant sizes and overseas travel; however, there are a limited number of executive aircraft that can accommodate larger groups and fly long distances. DOD guidance specifies that large executive aircraft (i.e., capable of carrying 15 or more passengers) will be approved only for groups of 5 or more members of Congress. The Air Force has two types of large executive aircraft (C-40s and C-32s). In calendar years 2014 and 2015, we found that 76 percent of the congressional user flights used C-40 executive aircraft, which seat up to 36 passengers and can fly 5,000 nautical miles without refueling. In 2007, DOD established the Executive Airlift Scheduling Activity to facilitate sharing of executive aircraft among the military services and combatant commands when requests exceed capacity. Multiple officials from the services and DOD's components told us that this sharing approach generally works, and that services usually agree to use their service secretary controlled aircraft to fly officials outside of their service, when asked. Our analysis showed that service secretary controlled aircraft accounted for 13 percent of the executive flights in 2014, and 15 percent of the executive flights in 2015. Table 6 shows that while service secretary controlled aircraft generally flew users from within their associated service, approximately 18 percent of service secretary controlled flights supported users from outside their service. DOD Generally Followed Its Approval Guidance for a Select Set of Executive Flights Reviewed We analyzed flight request packages from a nongeneralizable, random sample of 53 executive flights taken during calendar years 2014 through 2015 and, consistent with a report we issued in 2014, we found that for these select flights DOD generally followed its guidance for approving executive aircraft use. The Secretaries of the Military Departments and Combatant Commanders review and approve OSA aircraft requests within their respective Departments and Commands. The Air Force Deputy Chief of Staff for Operations, Plans and Requirements is also responsible for scheduling congressional and White House support missions. DOD guidance defines a list of procedures for approving the use of OSA. As shown in Figure 1, DOD guidance requires each OSA flight request package to contain specific information, such as the name and rank of traveler, itinerary, cost comparison if needed, and appropriate signatures. Although some packages were missing items, we did not find evidence to suggest the requested flight should have been disapproved. Specifically, 51 of the 53 flight request packages listed the names and titles or ranks of travelers, and 43 of the 53 flight request packages included a signed request. In addition, 42 out of the 53 flight request packages included the purpose of travel and 40 out of the 53 flight request packages included the senior DOD traveling official's signature certifying use of the aircraft. We also found that 24 out of the 53 flight request packages were for authorized users. The request packages for authorized users are required to include additional information and we found that most of the packages included most of the information. For example, all of the 24 packages included the military department or agency of travelers, and 20 of 24 packages included a statement that the travel requirements of DOD guidance have been met. In addition, 17 of 24 packages included documentation such as an explanation as to why scheduling requirements could not be changed to permit the use of commercial air, and a justification to include a statement of commercial air costs. We discussed any items that were missing with DOD officials and did not find evidence to suggest the requested flights should have been disapproved. In recent years, DOD has implemented a consistent process to validate the size of its OSA fleet. The process results in a general determination of the sufficiency of the OSA inventory, and the 2015 and 2016 determinations were expressed in terms of risks to mission accomplishment. The services do not generally use the validation process determinations as a basis for their OSA aircraft procurement and divestment decisions. In 2011, guided by a memorandum from the Vice Chairman of the Joint Chiefs of Staff and DOD Instruction 4500.43, Operational Support Airlift, DOD began to implement a structured, repeatable approach to validate its OSA fleet on an annual basis, to comply with Office of Management and Budget guidance. The Vice Chairman's memorandum established working and steering groups to provide input and oversight to the process and the instruction laid out many of the details of the new fleet validation process. The instruction assigned DOD and service officials a variety of responsibilities with regard to OSA aircraft. For example, in addressing the need to gain efficiencies by sharing aircraft and flight data across the department, it specifically instructed each of the military department secretaries and the combatant commanders to budget for the costs of their OSA aircraft, and to manage those aircraft as required to maximize wartime readiness, efficiency, cost-effectiveness and peacetime utilization. DOD Instruction 4500.43 noted that DOD is required to conduct validations of its OSA aircraft inventory and requirements to determine the sufficiency of the fleet, and it instructed the Chairman of the Joint Chiefs of Staff to conduct an annual OSA aircraft review and to provide the results to the Secretary of Defense. The instruction lists a wide range of requirements that the fleet validation is to be based upon. These include: peacetime engagement and support; travel for members of Congress; travel for DOD's required-use travelers; and a range of wartime requirements associated with contingency scenarios, specific contingency plans and concepts of operation, steady-state campaigns, posture planning efforts, and general and direct support. The OSA validation process begins when the Joint Staff and an independent contractor collect and analyze data from the services and combatant commands. The results of the analysis are then presented to the working and steering groups, and may go through additional reviews before the process concludes with a memorandum from the Chairman of the Joint Chiefs of Staff to the Secretary of Defense, which validates the fleet and addresses risk. Figure 2 shows the full extent of the process, and shows that some steps can be omitted if there are no disagreements or contentious issues to resolve. In recent years, the OSA validation process has resulted in a general determination of the sufficiency of the OSA fleet to meet requirements. This determination has been reported annually in memorandums from the Chairman of the Joint Chiefs of Staff to the Secretary of Defense. Throughout the validation process, the OSA aircraft inventory is compared to a broad set of requirements. Some of the anticipated future requirements are estimated based on historical aircraft usage rates. For example, executive aircraft requirements are estimated based on the past usage of executive aircraft by DOD's required users, Congressional users, and White House directed travelers. Because the usage of these travelers can vary from year to year, the Chairmen's memorandums refer to the requirements as estimates, and consequently, address the ability of the OSA fleet to meet these requirements in general terms. Table 7 shows that the size of the OSA fleet has declined each year since 2013, as well as the Chairmen's assessments. The Chairman's validation memorandums for 2015 and 2016 expressed the sufficiency of the OSA fleet in terms of risk, based on a risk matrix developed by the OSA working group in 2014. The OSA risk matrix categorizes risks as low, moderate, significant, or high based on the percentage of days DOD expects to be able to conduct all its required missions. In Table 8, we have converted the working group's risk-level percentages to numbers of days in a year. The Chairman's 2016 OSA fleet validation memorandum indicated that with a fleet of 45 executive aircraft the risk to mission accomplishment was moderate; and the mission risk for the nonexecutive fleet of 256 aircraft was low. Based on the risk matrix, this means DOD should be able to meet all of the flight requests for tier one and tier two users, White House directed travelers, and Congressional members and delegations, on between 336 and 343 days of the year. Stated more simply, those users can expect a shortage of available executive aircraft to affect some travel plans between 22 and 29 days of the year. Similarly, DOD expects that its nonexecutive aircraft may be unable to meet some mission requirement on up to 22 days of the year. The Chairmen's validation memorandums are generally not used to support OSA aircraft procurement or divestment decisions. As previously noted, OSA guidance instructs the military department secretaries and the combatant commanders to budget for the costs of their OSA aircraft, and to manage those aircraft as required to maximize wartime readiness, efficiency, cost-effectiveness and peacetime utilization. Service officials told us their decisions to divest or replace OSA aircraft are generally made based on internal service assessments concerning the age and maintenance condition of the aircraft, and the need to balance OSA aircraft requirements against other service priorities. For example, Navy and Army officials said that they retired C-20 aircraft because the aircraft were old and expensive to maintain. On April 8, 2014, when General Dempsey issued the first annual OSA validation memorandum, he included an attachment which showed that the services and U.S. Special Operations Command had programed reductions of 68 aircraft and he recommended the exact same reduction in the size of the OSA fleet (from 344 to 276 aircraft) through fiscal year 2019. The subsequent validation memorandums, for the 2014, 2015, and 2016 fleets, did not contain any specific recommendations for force structure changes, but each memorandum noted that the services were continuing to identify efficiencies and program reductions in their OSA fleets. We are not making recommendations in this report. DOD provided technical comments on a draft of this report, which we incorporated as appropriate. We are sending copies of this report to the appropriate congressional committees; the Secretary of Defense; the Under Secretary of Defense for Acquisition, Technology and Logistics; the Chairman of the Joint Chiefs of Staff; the Secretaries of the Military Departments, and the Commandant of the Marine Corps; the Commander of the United States Transportation Command; and other interested parties. The report is also available at no charge on GAO's website at http://www.gao.gov. If you or your staff have any questions about this report, please contact me at (202) 512-5257 or merrittz@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. Key contributors to this report are listed in appendix V. The Department of Defense (DOD) defines an aircraft mishap as an event resulting in death, injury, illness or property damage. DOD guidance defines four categories or classes of mishaps according to severity: Class A: Mishap resulted in a fatality, a permanent total disability, damage equal to or greater than $2 million, or a destroyed aircraft. Class B: Mishap resulted in a permanent partial disability, damage equal or greater than $500,000, but less than $2 million, or hospitalization for inpatient care of three or more individuals (not including observation or diagnostic care). Class C: Mishap resulted in a nonfatal injury or occupational illness that caused loss of one or more days from work not including the day or shift it occurred, or damage equal or greater to $50,000, but less than $500,000. Class D: Mishap resulted in a recordable injury or illness not otherwise classified as Class A, B, or C, or damage equal or greater to $20,000, but less than $50,000. While any reportable mishap is, by definition, a matter of concern, the rate of mishaps per flight (or sortie) is low for OSA aircraft. Complete historical flight data is not available for the OSA fleet. However, a calculation based on an extrapolation that uses the average sortie numbers from the 2016 OSA validation process analysis would yield a rate of 7 mishaps for every 10,000 sorties. Furthermore, DOD classifies its class A and B mishaps as its serious mishaps, and these mishaps accounted for 22 of the 174 total OSA mishaps from fiscal years 2007 through 2016. See Table 9 for the complete mishap data for that period. Appendix II: Information on Maintenance of Operational Support Airlift (OSA) Based on our interviews with service maintenance officials and analysis of service maintenance data, we found that: Contractors perform almost all executive and nonexecutive OSA aircraft maintenance, including most organizational-level and depot- level maintenance. In some instances, one contract covers aircraft from more than one service. For example, the Air Force manages the support contract for the Air Force, Army, and Navy C-37 aircraft. All the services require that maintenance for these aircraft comply with Federal Aviation Administration standards for similar types of commercial aircraft. Many of the OSA aircraft are more than 20-years-old. Upcoming depot maintenance and modification periods will reduce the availability of 2 or 3 C-32 and 2 or 3 C-40B executive aircraft. According to Air Force officials, various capability upgrades and modifications will be made so the planes can continue to meet Federal Aviation Administration standards and customer requirements. Each of the maintenance and modification actions is scheduled to take between 10 days and 9 months. In response to this situation, in June 2016, the Executive Secretary sent a memorandum to the military departments, the Assistant Secretary of Defense for Legislative Affairs, and others in DOD, with a copy to the Director of the White House Military Office, alerting them that availability of these larger capacity aircraft will be limited until 2018. The memorandum also asked the addressees to be prepared for flight cancellations due to short notice higher priority missions and to always have commercial air transportation planned as a backup. As shown in tables 10 (Air Force), 11 (Army), and 12 (Navy), many OSA aircraft are over 20 years old and have availability or mission capable rates around or above 70 percent. However, some OSA aircraft have lower availability rates, such as the Air Force C-37 (58 percent) and the Army C-37 (65 percent). To examine the extent to which DOD used executive aircraft, and the extent the usage for select flights complied with guidance, we identified and reviewed the guidance DOD and its components have in place to approve the use executive aircraft. Additionally, we interviewed officials from the Joint Staff, U.S. Transportation Command, the military services, the Office of the Secretary of Defense Executive Secretary, and the Office of the Assistant Secretary of Defense for Legislative Affairs and discussed their roles in approving the use of executive aircraft. Because there was no central source for current and historical executive flight data, we obtained the most current data available--calendar year 2014 and 2015 executive aircraft flight data--from both the Joint Staff and the military services. We then analyzed the data to identify the portions of the total flights that supported various categories of DOD and non-DOD travelers. We also analyzed the calendar year 2014 and 2015 flight data by type of aircraft used. We also analyzed a nongeneralizable, random sample of 53 executive OSA flights and compared the documentation in the flight request packages to the flight package documentation requirements listed in DOD's OSA guidance. The initial scope for the sample included all 19,752 flights conducted during calendar years 2014 through 2015. We received flight information from the services that indicated departure and arrival dates, departure and arrival locations, tiers of travelers, and service of travelers. Based on this, we compiled a unique list of flights, organized by flight type (Joint Staff or service secretary aircraft) and tier (tiers one, two, three, and four; below tier 2; congressional delegation; White House; and other). We then created 9 sampling strata as described in table 13, and distributed a sample of 100 flights proportionally across the strata where the sample was designed to achieve overall 95 percent confidence intervals within +/- 10 percentage points of an attribute estimate. In February 2017, we delivered the selected sample of 100 flights to the respective services with a request for the associated flight packages. However, we ultimately restricted our analyses to a select subset of 53 nongeneralizable flight packages for several reasons. Specifically, upon requesting flight packages, we learned that certain types of flights, for example, congressional user and combatant command flights were not collected by the services. As a result, it was determined the delivered select set of 53 flight packages could not be generalized to all flights in calendar years 2014-2015 due to the limited scope of the sampled flights with available packages and due to the small sample size, which would not provide precise estimates. We concluded that the data provided by the Joint Staff and the military services were sufficiently reliable for the purposes of our reporting objectives by interviewing each of the services and the Joint Staff about their databases used to enter and maintain flight data. To examine the process DOD uses to validate its OSA fleet size and the extent to which the process results have influenced force structure decisions, we gathered documentation on DOD's annual OSA validation process. The documentation we reviewed included DOD guidance, meeting minutes, briefings, and a methodology paper. We also analyzed the results of the OSA fleet validation process. Since 2014, the Chairman of the Joint Chiefs of Staff has presented these results to the Secretary of Defense in an annual OSA fleet validation memorandum. We also interviewed officials from the military services, Joint Staff, the U.S. Transportation Command, and a private contractor who supported the OSA validation process, to determine their roles in the annual validation process and to identify how the process results are used. We also discussed the basis for OSA force structure decisions with officials from the military services. We conducted this performance audit from June 2016 to June 2017 in accordance with generally accepted government auditing standards. Those standards require that we plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our findings and conclusions based on our audit objectives. We believe that the evidence obtained provides a reasonable basis for our findings and conclusions based on our audit objectives. Tables 14 through 22 show some key facts about DOD's different types of OSA aircraft, along with a picture of each type of aircraft. In addition to the contact named above, the following staff members made key contributions to this report: Michael Ferren, Assistant Director, Brenda M. Waterfield, David M. Ballard, Vincent M. Buquicchio, Patricia F. Donahue, Amie Lesser, Marc Meyer, Dan Royer, Leigh Ann Sheffield, and Sonya L. Vartivarian.

Summary:
OSA missions support the movement of a limited number of high-priority passengers and cargo with time, place, or mission-sensitive requirements. DOD's OSA aircraft are variants of commercial aircraft. OSA aircraft are categorized as either executive (used to transport DOD, congressional, and cabinet officials) or non-executive (used to fulfill wartime or contingency needs). As of May 2017, DOD had 287 OSA aircraft--44 executive and 243 non-executive--about 6 percent of DOD's airlift/cargo/utility aircraft. House Report 114-537 and Senate Report 114-255 included provisions for GAO to review the use and size of the OSA fleet. This report examines the extent to which DOD (1) used OSA executive aircraft in 2014 and 2015, and if this usage complied with guidance; and (2) has a process to validate its OSA fleet size. GAO reviewed DOD guidance for approving the use of OSA aircraft, analyzed the most current executive aircraft flight data available--calendar years 2014 and 2015--and compared the approval documentation from a sample of those flights to DOD's guidance. GAO also reviewed documentation and interviewed officials to assess DOD's OSA validation process and results. In calendar years 2014 and 2015, government officials took thousands of flights on Operational Support Airlift (OSA) executive aircraft, and our review of a nongeneralizable sample of 53 flight packages found that those trips generally followed Department of Defense (DOD) guidance for requesting the use of government aircraft. DOD requires its officials in certain positions to fly on military aircraft, including OSA executive aircraft. It also authorizes, but does not require, officials in other government positions to fly on OSA executive aircraft. We analyzed the use of OSA executive aircraft during 2014 and 2015--the latest years for which data were available--and found that of the 19,752 executive flights conducted, 31 percent supported required users and 69 percent supported other authorized users. The Vice President, the First Lady, and other cabinet-level officials on White House support mission trips accounted for about 12 percent of the flights, and members of congress and congressional employees accounted for about 5 percent of the flights. DOD guidance requires documentation for each flight request including the rank or position of the traveler, itinerary, and in some cases, cost data. While not generalizable beyond these flights, our review of 53 flight request packages found that the packages generally contained most required documentation. Although some packages were missing items, we discussed those items with DOD officials, and we did not find evidence to suggest the requested flight should have been disapproved. In recent years, DOD has implemented a consistent process to validate the size of its OSA fleet and to have a risk assessment of the fleet's ability to meet requirements all 365 days per year. In 2016, for example, the executive fleet's risk-to-mission accomplishment was assessed as moderate, and the non-executive fleet's risk-to-mission was assessed as low. The services do not generally use the validation process determinations as a basis for OSA aircraft procurement and divestment decisions. According to service officials, those decisions are based on separate, independent evaluations of their force structure needs, which evaluate the age and maintenance conditions of their aircraft, and the need to balance OSA aircraft requirements against other service priorities. GAO is not making any recommendations in this report. DOD provided technical comments on a draft of this report, which GAO incorporated as appropriate.