Southwest is the world's largest operator of the Boeing 737, and was the launch customer of the 737-300, 737-500, and 737-700. The Boeing customer code for Southwest Airlines is H4 for the Classic and Next Gen 737s. For example, the -700 would be 737-7H4, and the -800 would be 737-8H4.
As of early 2026, Southwest Airlines remains the world’s largest operator of the Boeing 737, maintaining an all-Boeing fleet of over 810 aircraft. Their inventory is composed entirely of 737-700, 737-800, and the newer 737 MAX 8 models. Southwest’s business model is built on "fleet commonality," which allows for simplified maintenance, pilot training, and scheduling. Following closely is United Airlines, which has hundreds of 737s in its mainline fleet and thousands of 737 MAX aircraft on order as part of its "United Next" strategy. Other massive 737 operators include Ryanair in Europe (which operates over 500 of the 737-800 and MAX 8-200 variants) and American Airlines. While many global carriers are diversifying their fleets with Airbus A320s, Southwest’s commitment to the 737 makes it the definitive "737 giant" of the aviation world, using the aircraft for everything from short-hop inter-island flights in Hawaii to 5-hour transcontinental routes across North America.
Southwest maintains the largest Boeing 737 MAX fleet, though the Ryanair Group is close to knocking the US low-cost carrier from the top.
With approximately 6,500 airplanes in service, the Boeing 737 represents a quarter of the total worldwide fleet of large commercial jets flying today.
No 737-100s remain in commercial service. For more information, see Boeing's B737 family specifications. Note: The ICAO Designator B731 has been removed from ICAO Doc 8643 as aircraft of this type no longer exist in airworthy condition.
Because of the sheer intensity of the scrutiny the aircraft faced, the Boeing 737 MAX could be considered one of the safest in the world. In fact, among the dozens of models of commercial airliners around the world, it is likely the safest due to the amount of regulation testing that took place.
After manufacturing issues led to two incidents in 2019, the Boeing 737 MAX was grounded across the world. In 2021, after rigorous testing, Civil Aviation Authorities in many places in the world cleared the Boeing 737 MAX to fly again, including the US, Canada, the UK, Australia, Brazil, and the EU.
The Boeing 737 MAX aircrafts are returning to the skies. If there is an aircraft that you want to avoid it is this one. The 737MAX has been responsible for the deaths of 346 people in 2 separate plane accidents.
Despite the FlyersRights concerns, the FAA, Boeing and many pilots deem the 737 MAX safe to fly and many airlines have the plane in service. “I can say categorically that the 737 MAX product is safe,” then-acting FAA administrator Bill Nolen told members of the US Senate Commerce Committee in March.
With more efficient turbofans and improvements including sharklets, it offers up to 15% better fuel economy. Earlier A320s are now called A320ceo (current engine option). American Airlines is the largest A320 operator with 469 aircraft in its fleet.
The largest operators at that time were All Nippon Airways (74), United Airlines (64), American Airlines (50), Japan Airlines (47), Etihad Airways (39), Hainan Airlines (38), Air Canada (38), Qatar Airways (37), British Airways (35), Air India (27), Ethiopian Airlines (27), and other airlines operating fewer numbers of ...
According to the requirements specified in the FAA Type Certificate Data Sheet (pertinent excerpts shown below) the B737-800 requires a minimum flightcrew of 2 - a Pilot and Copilot.
A Boeing 737-700 ER can fly more than 12 hours; other models vary depending on the fuel tanks that are installed. Standard tanks allow around seven hours.
“If you could book a 737 500, and you find out it's a 737 MAX, technically they don't have to honor your request. … So you don't have a right to specify you are not going to go on a 737 MAX.”
It was found that Boeing had more accidents than expected, while Airbus had fewer (p = 0.015). In terms of fatalities, Boeing had more than expected, with Airbus fewer (p < 0.001). Looking at accidents alone, only the number of fatalities was statistically significantly different.