Intermountain Aviation
Corporate brand
UnclaimedA defunct American contract airline and aviation-services company that conducted overt commercial work while secretly operating as a Central Intelligence Agency proprietary company.
Last updated October 14, 2026
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Overview
Intermountain Aviation was an American aviation-services and contract-airline company established in 1961 and later identified as a secret proprietary company of the Central Intelligence Agency. It operated from Marana Air Park, northwest of Tucson, Arizona, a site now known as Pinal Airpark. The business presented itself publicly as a versatile aviation contractor, supporting the United States Forest Service, commercial and government customers, aircraft maintenance, aircraft storage, parachute demonstrations, specialized recovery work, and logistics in remote areas. Its visible activities included flying smokejumpers, transporting freight to Alaska’s North Slope, restocking fish from the air, operating helicopters and short-takeoff aircraft, and hosting public parachuting events. The company’s origins were connected to Sonora Flying Service, a Forest Service firefighting contractor that leased the former Marana Air Base in late 1960 and developed it into a publicly accessible aviation center. Intermountain Aviation was organized in Phoenix on September 25, 1961, and moved to the air park in early 1962. Robert E. Roberts acted as the nominal public representative during the first years, while Garfield “Gar” Thorsrud, a former Forest Service smokejumper, became the central operating manager and later served as president. The company’s ownership was concealed through Pan Aero Investments and related arrangements, allowing it to function as an apparently independent commercial operator. Intermountain was authorized to perform maintenance on aircraft of any type and could operate large aircraft on a contract basis as an uncertificated carrier. Because it was not a common carrier, it avoided much of the direct oversight then applied by the Civil Aeronautics Board to scheduled commercial airlines. This structure gave it flexibility to combine ordinary commercial work with highly specialized government contracts. Its public-facing capabilities included large-scale parachute demonstrations, experiments with the Fulton Skyhook recovery system, support for oil exploration in Alaska, aircraft storage, and logistics involving aircraft such as the B-17, C-46, T-28, B-26K, C-54, Caribou, Pilatus PC-6 Porter, Twin Otter, and helicopters. From the mid-1960s through the height of the Vietnam War, CIA-related work reportedly represented approximately 60 to 70 percent of Intermountain’s activity. The company was one of the CIA’s largest proprietary enterprises, alongside Air America and the agency’s insurance operations. Its covert or classified work included support for Project Coldfeet, operations connected with the Simba rebellion in the Congo, the movement of aircraft and personnel for Southeast Asian operations, and classified contracts involving United States military and scientific agencies. Marana’s proximity to Davis-Monthan Air Force Base also gave the company access to a large pool of stored aircraft that could be obtained, maintained, or modified for special missions. The CIA began reducing its aviation activities in 1972. As government work declined, Intermountain attempted to broaden its commercial base by transporting automobile components for major Detroit manufacturers, storing aircraft, and promoting Marana Air Park for corporate events and training. In 1973, it sold the automobile-parts operation and much of its commercial fleet to Rosenbalm Aviation. CIA ownership, which had previously been denied, became public in June 1974 after publication of a book identifying the company and confirmation by Arizona Congressman Morris K. Udall. Intermountain ceased operations on February 28, 1975, when Evergreen Helicopters acquired its remaining assets. Evergreen subsequently combined those assets with Johnson Flying Service, acquired later in 1975, to create Evergreen International Airlines. The latter continued operating until 2013. Thorsrud later became associated with Sierra Pacific Airlines, a Tucson-based charter and Forest Service contractor whose livery and some operating activities reflected elements of Intermountain’s legacy.
History
Intermountain Aviation emerged from the aviation and firefighting environment surrounding Marana Air Park in southern Arizona. Sonora Flying Service obtained a long-term lease on the former Marana Air Base in late 1960 and developed the location as both an aviation operating base and a public facility. The site included passenger accommodations, food service, recreational facilities, and aircraft used in Forest Service firefighting work. Its open public character helped support the company’s later strategy of concealing sensitive activity within an apparently ordinary aviation business. Intermountain was formed in Phoenix on September 25, 1961, and moved to Marana Air Park early the following year. Roberts was used as the public representative during its initial period, but Thorsrud was the important operating figure. The company was nominally associated with Pan Aero Investments rather than directly with the CIA. This ownership arrangement allowed Intermountain to operate as a commercial contractor while handling classified assignments. The company was authorized to maintain virtually any aircraft type and to operate large aircraft under contract without being a common carrier subject to the full regulatory framework applied by the Civil Aeronautics Board. Its overt business was broad. Intermountain supported Forest Service smokejumpers, transported freight, supplied remote industrial and oil-exploration projects, restocked fish in lakes and reservoirs, and operated helicopters and STOL aircraft. It also used demonstrations and public events to advertise its capabilities. The air park hosted major parachuting activities, including national competitions, and Intermountain demonstrated systems such as the Fulton Skyhook. A company promotional film highlighted North Slope logistics and remote aviation. The public profile was consistent with the company’s “hide in plain sight” approach. Behind those activities, intelligence and government work became dominant. From the middle of the 1960s through the peak of the Vietnam War, CIA-related operations reportedly accounted for roughly 60 to 70 percent of the company’s work. Intermountain was among the CIA’s largest proprietary businesses. Its role included supplying aircraft and pilots for anti-rebellion operations in the Congo, facilitating aircraft transfers connected with Portugal’s colonial wars despite an applicable arms embargo, and handling classified work for the United States Air Force, Atomic Energy Commission, Office of Naval Research, Department of Defense, and Army. Aircraft associated with the company included B-17s, T-28s, B-26Ks, C-46s, Caribous, Twin Otters, Pilatus Porters, and helicopters. The CIA’s decision in 1972 to reduce its aviation activities forced a commercial transition. Intermountain sought replacement business by carrying automobile components for major Detroit manufacturers and by developing aircraft storage and event facilities at Marana. More than 40 large commercial aircraft were reportedly stored at the air park by the end of 1972. The company sold the Detroit-related transportation operation and much of its commercial fleet to Rosenbalm Aviation in November 1973. The sale formed part of the broader dismantling of CIA aviation proprietaries. The company’s secret ownership became a public controversy. In 1970, a local official had connected an Intermountain-linked aircraft accident with the CIA, but the agency denied operating inside the United States. In June 1974, a former CIA employee’s bestselling book identified Intermountain as a CIA proprietary, and Congressman Morris K. Udall confirmed the relationship. The revelation exposed the contrast between the company’s public commercial identity and its intelligence role. Intermountain ended its independent existence on February 28, 1975, when Evergreen Helicopters acquired its remaining assets. Evergreen later combined them with Johnson Flying Service, forming Evergreen International Airlines. Thorsrud was dismissed by Evergreen in June 1975 and subsequently became associated with Mountain West Aviation and Sierra Pacific Airlines. Sierra Pacific continued some Forest Service-related work and used a visual identity reminiscent of Intermountain’s pale-blue and black scheme. The former Marana base, now Pinal Airpark, remains associated with commercial aircraft storage and the region’s aviation history.
- 1975
Assets are sold to Evergreen Helicopters
[1]Intermountain ceased operations on February 28, ending its independent corporate life.
- 1974
CIA relationship is publicly confirmed
[1]Public reporting and congressional confirmation identified Intermountain as a CIA proprietary company.
- 1973
Commercial airline activities are sold
[1]The Detroit automobile-parts operation and much of the commercial fleet were transferred to Rosenbalm Aviation.
- 1972
Commercial diversification begins during CIA aviation drawdown
[1]Intermountain expanded into automobile-parts transportation and aircraft storage as government work declined.
- 1969
Marana Air Park appears in a CBS football anniversary special
[1]CBS filmed a parachute segment at the air park for a television program marking professional football’s fiftieth anniversary.
- 1963
Project Coldfeet recovery support
[1]An Intermountain B-17 participated in the Arctic recovery operation using the Fulton Skyhook system.
- 1962
Operations move to Marana Air Park
[1]Intermountain established its principal base and maintenance presence at the Arizona air park.
- 1961
Intermountain Aviation is established
[1]The company was organized in Phoenix on September 25, 1961.
- 1960
Sonora Flying Service leases the former Marana Air Base
[1]The site was converted into Marana Air Park, providing the operating base from which Intermountain Aviation would later work.
Products and positioning
A flexible, technically capable contract aviation operator that maintained a public commercial profile while undertaking classified government and intelligence work.
Airline services · 1961
Contract air transport
Intermountain operated large aircraft on a contract basis rather than as a scheduled common carrier. Its work included freight, industrial logistics, government transportation, and specialized missions in remote or sensitive locations. The contract model gave the company operational flexibility and limited its exposure to the Civil Aeronautics Board’s common-carrier oversight.
Public-sector aviation · 1961
Forest Service aerial support
The company flew smokejumpers and performed related aerial work for the United States Forest Service. It also conducted fish-restocking flights and other support activities associated with remote-area resource management. These visible assignments helped establish Intermountain as a credible conventional aviation contractor.
Aviation engineering · 1962
Aircraft maintenance and modification
Intermountain held authority to maintain aircraft of any type. Its Marana base could service a varied fleet of commercial, military, helicopter, and STOL aircraft, supporting both ordinary customers and classified government programs.
Industrial aviation
Remote logistics and North Slope support
Intermountain transported freight and supported oil-exploration activity in Alaska’s North Slope. The company promoted this capability in a marketing film emphasizing operations in areas where conventional ground transport was limited.
Specialized aviation systems · 1963
Fulton Skyhook recovery support
The company helped demonstrate and refine the Fulton Skyhook, an aerial extraction system. The technology was used in the recovery phase of Project Coldfeet and later adapted for larger aircraft in Southeast Asian operations.
Controversies
Marketing campaigns
- 1963Project Coldfeet
Arctic
Intermountain provided a B-17 and support for an operation that recovered intelligence materials and personnel from an abandoned Soviet drift station in the Arctic Ocean.
Outcome. The recovery demonstrated the practical use of the Fulton Skyhook in a hazardous polar environment.
- 1960Marana Air Park public aviation promotion
United States
The company and its associated operators promoted Marana as an open aviation center with public events, accommodation, demonstrations, and commercial services.
Outcome. The public-facing site helped embed sensitive aviation work within a visible commercial setting.
Brand decisions
1975
Remaining assets transferred to Evergreen HelicoptersM&ABackground
Following the CIA’s withdrawal and the reduction of government business, Intermountain no longer continued as an independent operator.
Action taken
Evergreen Helicopters acquired the remaining assets on February 28 and subsequently combined them with Johnson Flying Service.
Aftermath
The combination helped form Evergreen International Airlines, which later operated until 2013.
1973
Sale of commercial operations to Rosenbalm AviationM&ABackground
The CIA was winding down aviation activities and Intermountain needed to reduce or transfer its commercial operations.
Action taken
The company sold its automobile-parts transportation business and most of its commercial fleet to Rosenbalm Aviation.
Aftermath
The transaction sharply reduced Intermountain’s overt commercial airline presence before the final asset sale in 1975.
1972
Diversification into automobile-parts transport and aircraft storageStrategyBackground
Government-related aviation work was declining as the CIA moved to reduce its aviation activities.
Action taken
Intermountain devoted aircraft to transporting automobile components for major Detroit manufacturers and expanded its aircraft-storage and event-facility business.
Aftermath
The diversification did not prevent the eventual sale of the commercial operation and the company’s remaining assets.
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