Flight Friday: How Southwest's Boeing 737 Fleet Is Evolving

max 8 under nose
Credit: Ashlee D. Smith/Southwest Airlines

With only weeks to go until the aviation community meets in Atlanta for MRO Americas 2025, this week's #FlightFriday looks at a carrier causing a stir: Southwest Airlines.

Southwest relies exclusively on the Boeing 737s for its operations. More specifically, it relies on only three types of the 737. The current in-service fleet consists of almost 350 737-700s, with an average age of 19 years, just over 200 737-800s, with an average fleet age just shy of 10 years, and more than 250 737-8s, with an average age still under 3.5 years.

Following the MAX grounding in March 2019, Southwest went into the pandemic only operating -700s and -800s. It had a larger 737-700 fleet of 500 aircraft fitted in a 143-seat layout,  compared to a little over 200 of the 175-seat 737-800s. Back then, the -700 accounted for more than three-quarters of Southwest's monthly flights.

As no new MAX aircraft could be delivered to Southwest due to the grounding, the -700s and -800s remained in service. Since deliveries resumed in February 2021, more than 200 175-seat MAX aircraft have been delivered to the airline. That has allowed Southwest to remove some of its -700s from service, which has seen that sub-fleet contract to some 350 aircraft. 

The MAXs have the same 175-seat layout as the -800s. The pivot of switching out a 143-seat aircraft with a 175-seat aircraft bolsters Southwest’s available seat miles (ASM) and also helps the airline become greener, because the MAX is much more efficient than a -700 and has more seats, therefore lowering the emissions per ASM figure.

The increase in the MAX fleet means that as a proportion of aircraft flying, the MAX now equates to a little under 30% of all Southwest flights, with the -700 now accounting for less than half. 

The airline has more than 200 737-8s on order, alongside 300 orders for the still yet-to-be-certified 737-7. Southwest has almost enough aircraft on order to replace its legacy 737NG fleet one-for-one with MAX aircraft.

This data was put together using Aviation Week’s Tracked Aircraft Utilization database Find out more

Daniel Williams

Based in the UK, Daniel is Director of Fleet Data Services for Aviation Week Network. Prior to joining Aviation Week in 2017, Daniel held a number of industry positions analyzing fleet data.

FlightFriday

Flight Friday is compiled using data from Aviation Week Intelligence Network’s (AWIN) Tracked Aircraft Utilization module, the most comprehensive and accurate solution for global tracking of aircraft utilization. 

Based on recorded flight movements from ADS-B data, combined with AWIN’s robust fleet intelligence, users gain insight into the aircraft’s actual versus reported movement, down to the tail number. This unique solution provides users a more up-to-date and comprehensive analysis of aircraft utilization.