Question: Clipper Cargo was a subsidiary cargo airline of  the principal and largest international air carrier in the United States that was founded in what year?

Passages:
The Montreal Convention (formally, the Convention for the Unification of Certain Rules for International Carriage by Air) is a multilateral treaty adopted by a diplomatic meeting of ICAO member states in 1999.  It amended important provisions of the Warsaw Convention's regime concerning compensation for the victims of air disasters.  The Convention attempts to re-establish uniformity and predictability of rules relating to the international carriage of passengers, baggage and cargo.  Whilst maintaining the core provisions which have served the international air transport community for several decades (i.e., the Warsaw regime), the new treaty achieves modernization in a number of key areas.  It protects passengers by introducing a two-tier liability system that eliminates the previous requirement of proving willful neglect by the air carrier to obtain more than US$75,000 in damages, which should eliminate or reduce protracted litigation. Lynden Air Cargo is an American cargo airline based in Anchorage, Alaska, USA.  It operates scheduled services and on demand charter, international and domestic flights, including services for the US military.  Its main base is Ted Stevens Anchorage International Airport.  Subsidiary company Lynden Air Cargo PNG Ltd, based in Lae, Papua New Guinea, offers air cargo charters in the Western Pacific region including Australia and south east Asia. Air Midwest, Inc., was a Federal Aviation Administration Part 121 certificated air carrier that operated under air carrier certificate number AMWA510A issued on May 15, 1965.  It was headquartered in Wichita, Kansas, United States, and was a subsidiary of Mesa Air Group.  Besides initially flying as an independent air carrier, it later operated code sharing feeder flights on behalf of Eastern Air Lines as Eastern Air Midwest Express, on behalf of Trans World Airlines (TWA) as Trans World Express and on behalf of US Airways as US Airways Express.  It also operated feeder flights on behalf of Braniff (1983-1990) and Ozark Air Lines in addition to flying for Mesa Airlines.  Air Midwest was shut down by its parent company, Mesa Airlines, in June 2008. LATAM Cargo Brasil, formerly "TAM Cargo" and previously "ABSA Cargo Airline", is a cargo airline based in Campinas, Brazil.  It operates scheduled services within Latin America and between Brazil and the United States, as well as charter services.  Its main base is Viracopos International Airport. Pan Am Cargo or Clipper Cargo was a subsidiary cargo airline of Pan American World Airways.  Pan Am Cargo first used propeller aircraft just as the Douglas DC-4.  In 1963, Pan Am's all cargo jet service began in 1963 with Boeing 707-321C and it dominated Pan Am in air cargo market. Air Wisconsin Airlines is a regional airline based at Appleton International Airport in the town of Greenville, Wisconsin, United States, near Appleton.  Air Wisconsin is the largest privately held regional airline in the United States.  It currently operates regional jet flights as American Eagle under contract to American Airlines via a code sharing agreement, serving cities in the U.S. and Canada with hubs at Boston Logan International Airport (BOS), Charlotte Douglas International Airport (CLT), Philadelphia International Airport (PHL) and Ronald Reagan Washington National Airport (DCA) .  Air Wisconsin previously operated United Express service on behalf of United Airlines followed by US Airways Express service on behalf of US Airways prior to becoming an American Eagle regional air carrier.  The company has announced it will once again partner with United Airlines as a United Express code sharing air carrier with primary hubs to be located at Chicago O'Hare International Airport (ORD) and Washington Dulles International Airport (IAD) beginning in September 2017 and will be "exclusively operating" as United Express by March 2018. Air America was an American passenger and cargo airline covertly owned and operated by the US government between 1950 and 1976.  It was used as a dummy corporation for Central Intelligence Agency (CIA) operations in China.  The CIA did not have enough work to keep the asset afloat and the National Security Council farmed the airline out to various government entities that included the USAF, US Army, USAID and for a brief time France.  Essentially, Air America was used by the US government covertly to conduct military operations, posing as a civilian air carrier, in areas the US armed forces could not go due to treaty restraints contained in the 1954 and 1962 Geneva Accords. CJSC "Aeroflot-Cargo" (Russian: ЗАО «Аэрофлот-Карго» ) was a fully owned subsidiary of Aeroflot, founded on 26 October 2005 and incorporated on 19 April 2006.  It was the second largest cargo airline in Russia, behind Volga-Dnepr subsidiary AirBridge Cargo.  In June 2009 the shareholders of Russia's flagship air carrier, Aeroflot, decided to declare the company's cargo subsidiary, Aeroflot Cargo, bankrupt. Martinair, legally "Martinair Holland N.V.", is a Dutch cargo airline headquartered and based at Amsterdam Airport Schiphol and a subsidiary of Air France-KLM.  The airline was founded in 1958 by Martin Schröder.  Since 2011, Martinair has operated entirely as a cargo airline with scheduled services to 20 destinations worldwide and additional charter flights.  Prior to that date, passenger flights were also operated. Pan American World Airways, known from its founding until 1950 as Pan American Airways and commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991.  Founded in 1927 as a scheduled air mail and passenger service operating between Key West, Florida, and Havana, Cuba, the airline became a major company credited with many innovations that shaped the international airline industry, including the widespread use of jet aircraft, jumbo jets, and computerized reservation systems.  It was also a founding member of the International Air Transport Association (IATA), the global airline industry association.  Identified by its blue globe logo ("The Blue Meatball"), the use of the word "Clipper" in aircraft names and call signs, and the white pilot uniform caps, the airline was a cultural icon of the 20th century.  In an era dominated by flag carriers that were wholly or majority government-owned, it was also the unofficial overseas flag carrier of the United States.  During most of the jet era, Pan Am's flagship terminal was the Worldport located at John F. Kennedy International Airport in New York City.

Supporting sentences:
Pan Am Cargo or Clipper Cargo was a subsidiary cargo airline of Pan American World Airways. Pan American World Airways, known from its founding until 1950 as Pan American Airways and commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991.  Founded in 1927 as a scheduled air mail and passenger service operating between Key West, Florida, and Havana, Cuba, the airline became a major company credited with many innovations that shaped the international airline industry, including the widespread use of jet aircraft, jumbo jets, and computerized reservation systems.