Flying Tiger Line, also known as Flying Tigers, was the first scheduled cargo airline in the United States and a military charter operator during the Cold War era for both cargo and personnel (the latter with leased aircraft). The airline was bought by Federal Express in 1989.

The airline was named after the Flying Tigers fighter unit of World War II, officially the 1st American Volunteer Group. After returning to the United States in 1945, ten former AVG pilots led by Robert William Prescott established the Flying Tiger Line on 24 June 1945 under the name National Skyway Freight using a small fleet of 14 Budd Conestoga freighters purchased as war surplus from the United States Navy. The pilots and two ground crew provided half of the initial investment, with the balance coming from California oil tycoon Samuel B. Mosher. For the next four years, Flying Tiger Line carried air freight on contract throughout the U.S. and, as the airline expanded, carrying supplies to U.S. troops under Gen. Douglas MacArthur during the occupation of Japan.

In 1949, the Civil Aeronautics Board (CAB) awarded Flying Tiger Line (along with Slick Airways) a scheduled cargo certificate for a transcontinental route from Los Angeles and San Francisco, California to Boston, Massachusetts. Shortly afterwards, the company began chartering passenger aircraft for group travel as well; its Lockheed Super Constellation, Douglas DC-4 and DC-6 fleet comprised the largest trans-Atlantic charter operation through the 1950s.

During the Korean War, Flying Tiger aircraft were chartered to transport troops and supplies from the United States to Asia; Flying Tigers later received a cargo route award to Japan, China, and Southeast Asia. The airline also played a major role in the construction of the Distant Early Warning Line, flying equipment to remote outposts in northern Canada and Alaska.

Flying Tiger Line adopted the Canadair CL-44 swing-tail aircraft in 1961, becoming one of the first carriers in the world to offer aerial pallet shipping service.

Flying Tiger Line began operating jet aircraft on September 27, 1965, when the first (as N322F) of four Boeing 707s was delivered. On 15 November that same year, a modified Flying Tigers Boeing 707-349C made the first ever aerial circumnavigation of the Earth via the poles, in 62 hours 27 minutes. The aircraft carried additional fuel in two additional tanks installed in the main cabin. The Boeing 707 remained in the fleet for only a few years and was replaced by the higher-payload Douglas DC-8, the largest civilian airliner until the Boeing 747 entered service. The first Douglas DC-8-63F, registered as N779FT, was delivered to the airline on June 26, 1968, and the other eighteen followed until 1972.

In 1974, the airline took delivery of its first Boeing 747. Flying Tigers then placed orders for brand-new Boeing 747-200F freighters designated the Boeing 747-249F, which at the time were among the heaviest commercial airplanes flying, weighing 823,000 pounds (373,000 kg). These aircraft had the powerful "Q" (Pratt & Whitney JT9D-7Q) engines and heavy landing gear and could simultaneously carry both 250,000 pounds (110,000 kg) of fuel and 250,000 pounds (110,000 kg) of cargo loaded through both the nose door and the side door at the same time. Aircraft loaders had earlier refused to work at the extreme 30 feet (9 m) height necessary for loading freight on the upper deck, so the "supernumerary area" or "hump" was configured with 19 first class seats instead which were used to transport livestock handlers, charter agents and mechanics as well as dead-heading pilots and flight attendants.

Tiger's Ad Hoc Charter livestock flights provided airlift for exotic animals. Two examples were thoroughbred racehorses and show animals from Stansted, England to the Melbourne Cup, as well as breeding stock cattle (milk supply) to nations such as Japan and Thailand. They became known for carrying a number of unique cargoes, including Shamu the SeaWorld killer whale and the torch of the Statue of Liberty.