Operational Support Airlift: Fleet Sufficiency is Assessed Annually
Published: 2017-06-28T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: 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.
section_title: What GAO Found
paragraphs: 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.
section_title: What GAO Recommends
paragraphs: GAO is not making any recommendations in this report. DOD provided technical comments on a draft of this report, which GAO incorporated as appropriate.

section_title: Letter
paragraphs: The Department of Defense (DOD) describes Operational Support Airlift  (OSA) missions as a special category of airlift missions that involve the  movement of a limited number of high-priority passengers and cargo with  time, place, or mission-sensitive requirements. OSA missions can be  performed by a wide variety of aircraft, but DOD generally describes its  OSA aircraft fleet in terms of two groups, its executive aircraft and its  nonexecutive aircraft. Executive aircraft provide air transportation for  federal and DOD-approved senior leaders, and are configured to support  travel when other aircraft do not provide the timeliness, security,  communications capability, or workspace required. Executive aircraft  missions include transporting the Vice President, senior DOD officials  such as the Secretary of Defense and the Chairman of the Joint Chiefs of  Staff, cabinet, other high-ranking executive branch officials, and members  of Congress. Nonexecutive aircraft are used to fulfill wartime  requirements, contingency operations, domestic support missions, and  day-to-day activities. As of May 2017, DOD had 287 OSA aircraft—44  executive and 243 nonexecutive aircraft, which is a small portion of  DOD’s overall aircraft inventory. In fiscal year 2017, DOD operated 4,517  total aircraft in the airlift/cargo/utility category, which includes OSA aircraft  according to DOD’s Annual Aviation Inventory and Funding Plan. In fiscal  year 2016, DOD had allocated more than $890 million to operate and  maintain its OSA aircraft, according to budget documents.
House Report 114-537 and Senate Report 114-255 accompanying  proposed bills for the National Defense Authorization Act for Fiscal Year  2017 included provisions for us to review aspects of DOD’s management  of OSA aircraft, including the utilization of the aircraft and the validation of  its fleet size. This report examines the extent to which: (1) DOD used  OSA executive aircraft in 2014 and 2015 and the usage for select flights  complied with guidance; and (2) DOD has a process to validate its OSA  fleet size. Additionally, we provide information on OSA aircraft mishaps in  appendix I, and maintenance-related information in appendix II.
For objective one, we identified and reviewed DOD’s and its components’  guidance related to the use of executive aircraft. 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  selected 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. 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 group respectively about their databases  used to enter and maintain flight data. 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.
For objective two, 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. We reviewed  and analyzed the OSA fleet validation memorandums—issued annually since 2014—from the Chairman of the Joint Chiefs of Staff to the  Secretary of Defense. 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. Appendix III provides a  more detailed description of our scope and methodology.
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.
subsections: section_title: Background
subsections: section_title: Overview of OSA Aircraft
paragraphs: 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.
section_title: Approval Authorities for the Use of Government Aircraft and Air Travel
paragraphs: 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.
section_title: Required and Authorized Users
paragraphs: 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.
section_title: Executive Aircraft Supported Thousands of Annual Flights for a Variety of Users and for Select Flights DOD Generally Followed Its Guidance for Approving Use
paragraphs: 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.
subsections: section_title: Executive Aircraft Use
paragraphs: 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.
section_title: DOD Recently Implemented an Annual OSA Validation Process
paragraphs: 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.
subsections: section_title: OSA Guidance and the Current Validation Process
paragraphs: 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.
section_title: Validation Process Results in a General Determination of OSA Fleet Sufficiency
paragraphs: 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.
section_title: Services Generally Make Force Structure Decisions Independent of the Validation Process
paragraphs: 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.
section_title: Agency Comments
paragraphs: 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.
section_title: Appendix I: Operational Support Airlift (OSA) Mishap Data
paragraphs: 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.
section_title: Appendix II: Information on Maintenance of Operational Support Airlift (OSA)
paragraphs: 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).
section_title: Appendix III: Scope and Methodology
paragraphs: 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.
section_title: Appendix IV: Description and Pictures of Operational Support Airlift (OSA) Aircraft
paragraphs: 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.
section_title: Appendix V: GAO Contact and Staff Acknowledgements
subsections: section_title: GAO Contact
section_title: Staff Acknowledgments
paragraphs: 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.