History: 5 Defunct US airlines you've never heard of

Today, the United States commercial aviation industry looks drastically different than it did 20 years ago, which would be virtually unrecognizable compared to the US aviation industry of the 1980s. Over time, airlines have developed from small, regional market-oriented players into massive global behemoths, each operating hundreds of aircraft today.

Over time, there have been dozens of mergers and acquisitions, each of which has had its own impact on the industry. Over time, however, airlines have continued to see profits grow through scaling up to reduce their per-passenger costs, something that makes it extremely challenging for smaller airlines to survive over time.

Furthermore, multiple different supply and demand shocks throughout the 1980s, 1990s, and 2000s have pushed some airlines into dire financial straights, such as during multiple oil price hikes and in the period following the September 11th terrorist attacks in which air travel demand decreased significantly. As a result, the history books are littered with defunct US airlines that once maintained healthy fleets and operated extensive route networks back in their heyday.

Some of these airlines were major transcontinental carriers, while others were smaller, more market-oriented airlines. While some of these airlines were eventually merged into a larger airline that we know well today, others simply ceased to exist after ending commercial operations. Let's take a deeper look at five obscure defunct airlines in the United States that you likely haven't heard of.

1 Key Airlines

Operated between: 1968 and 1993

Originally founded as Thunderbird Airlines in 1964 before a later name change in 1969, the airline began operating as a commuter and air charter airline flying across the western United States. By 1972, the airline had begun expanding through mergers and acquisitions, acquiring Sun Valley Airlines in 1972 and adopting the name Sun Valley Key Airlines. The airline operated scheduled passenger services in later years out of a hub in Savannah, Georgia, and operated services with all the following jet aircraft:

• McDonnell Douglas MD-83
• Boeing 727
• Boeing 737
• McDonnell Douglas DC-10

Key Airlines, like many other airlines of the era, would be sold when it was acquired by Presidential Airways in 1986 who later sold it to World Airways just one year later. By 1992, Key Airlines had been sold one more time and soon filed for Chapter 11 bankruptcy protection, leading to the sale of almost all of its aircraft. The airline's assets were fully liquidated by May 1993.

2 Lake Central Airlines

Operated between: 1950 and 1968

A regional commercial airline that operated a network primarily serving destinations within the Midwest and Mid-Atlantic, Lake Central Airlines operated for about 18 years and saw the world of aviation transition into the jet age. The airline would eventually merge the carrier into Allegheny Airlines, which was later acquired by USAir, a company that eventually became US Airways and merged into American Airlines in 2015. The carrier operated out of a hub at Indianapolis International Airport (IND), and operated flights using all the following aircraft:

• Convair CV-340
• Convair CV-580
• Curtiss C-46 Commando
• Douglas DC-3
• Douglas C-47 Skytrain
• Douglas C-53 Skytrooper
• Nord 262A

3 Mackey Airlines

Operated between: 1953 and 1967

Mackey Airlines was a small US-based scheduled international airline that operated flights between the state of Florida and the Bahamas, under a special certificate from the Civil Aeronautics Board, the federal agency that rigidly regulated US airlines before the Airline Deregulation Act of 1978. The carrier was founded by Joseph C. Mackey, a veteran who had learned to fly in the Second World War.

The airline grew throughout its 14 years of existence, acquiring Midet Aviation in 1956 before eventually being acquired by Eastern Air Lines in 1967. According to Aviation Week, the airline's fleet included the following aircraft:

4 Midway Airlines

Operated between: 1979 and 1991

Midway Airlines, a carrier that was founded in 1976, was intended to capitalize on the newly revitalized US aviation industry that emerged after the Airline Deregulation Act of 1978. An airline initially conceived as a low-cost carrier that later adapted to a full-service model, Midway Airlines brought new life to Chicago's Midway Airport (MDW).

While many other airlines went bankrupt in the 1980s, Midway Airlines managed to survive, but a failed attempt to expand by purchasing Eastern Air Lines' Philadelphia International Airport (PHL) hub led it to file for bankruptcy, according to The Chicago Tribune. The airline's fleet included the following three aircraft models:

• Boeing 737-200
• McDonnell Douglas DC-9
• McDonnell Douglas MD-80 family (multiple variants)

5 New York Air

Operated between: 1980 and 1987

New York Air was a budget airline based out of the city's LaGuardia Airport (LGA) and was owned by the Texas Air Corporation throughout its relatively brief existence. The airline served destinations across the East Coast from its primary hub, operating routes that catered to vacationers (such as those to cities in Florida) and those that were conducive to travelers who were visiting friends and relatives (such as its flights to Midwestern cities like Pittsburgh and Ohio).

Eventually, the airline would be acquired by Continental Airlines and would cease flying under its own brand on February 1st, 1987. The airline was well-known for its onboard snack offerings, which were referred to as "The Flying Nosh." The carrier's fleet included all the following aircraft:

• McDonnell Douglas MD-82
• McDonnell Douglas DC-9
• Boeing 737-300