Southwest Airlines is a record-breaker of an airline for many reasons. Not only is it the world's largest low-cost airline but it is also the biggest operator of the Boeing 737. It has 752 aircraft in its current fleet, but why is the 737 the only aircraft it flies?

Southwest Airlines is the biggest Boeing 737 operator. Photo: Tomás Del Coro via Wikimedia Commons

How did Southwest get its 737s?

Back in 1971, Southwest Airlines started with its very first Boeing 737. It was a 737-200, of which the airline eventually ended up having 64 over a period between 1971 and 2005.

The airline first came to consider the 737-200 when its idol Pacific Southwest Airlines took a look at the aircraft for its fleet. Founders of Southwest Airlines saw the success of the Pacific Southwest Airlines model and tried to make an airline that replicated it. So with the 737-200 in Pacific Southwest Airlines' sights, it made sense for Southwest to do the same.

But when it came to acquiring its aircraft, it was specific in its requirements.

The 737-200 was the first aircraft Southwest owned. Photo: Aero Icarus via Flickr

At the time, a Hawaiian airline, Aloha Airlines, was looking to get rid of some of its Boeing 737-200, of which it had 81 over the course of its lifetime. But Southwest rejected them on account that the short-haul flights of these aircraft between the islands of Hawaii would mean that the aircraft would likely need a fair bit of maintenance. Despite now flying its own fleet on inter-island routes through Hawaii, at the time Southwest wanted something new.

Conveniently, Boeing had just what the airline needed. Several unpainted, brand-new 737-200s were sitting with the aircraft manufacturer after the expansion plans for the intended airline fell through.

Co-founder of Southwest, Rollin King, sat with Muse Air founder, Marion Lamar Muse, and they spoke to Boeing. They asked for a deal within the hour on the -200 series or they would take their business elsewhere; specifically, to the Douglas Aircraft Company for its DC-9 aircraft.

Boeing accepted the deal and Southwest Airlines took three 737-200s and an option on a fourth one.

From humble beginnings

But that was just the start. Since then, Southwest Airlines has taken -300s, -500s, -700s, -800s as well as the MAX 8 aircraft into its fleet.

Only at one point in its history did Southwest Airlines divert its attention from the 737. For a period of eight years between 1979 and 1987, it also leased and flew around seven 727s but soon stopped and has returned to its 737 roots ever since.

A 737-700 from Southwest's fleet. Photo: Quintin Soloviev via Wikimedia Commons

When will Southwest give up the 737?

Earlier this year, there was talk of Southwest considering an Airbus order amidst the MAX grounding, but little seems to have come from it. Southwest Airlines still seems steadfast in its loyalty to Boeing.

There are also perks that come with operating just one aircraft type. It means potential discounts on large orders and only needing to train staff on one type of aircraft for maintenance.

And as Southwest Airlines is still looking pretty successful, there is no need for it to change. Its sights are still set on profitability, having cut 17 routes to invest more in better-performing routes as well as expanding in the Hawaiian market. And it's likely that the Boeing 737 will take them through it all.

Do you think Southwest Airlines will ever introduce another aircraft in its fleet? Let us know!