Southwest is speeding up the Boeing 737 Max's return with an earlier start date and 35 new jets in 2021

• Southwest Airlines said Wednesday that it plans to fly passengers on the Boeing 737 Max again in March.
• CEO Gary Kelly had previously said the jet's first flight would "likely take place no sooner than the second quarter of 2021."
• Southwest will receive 35 more jets in 2021, more than doubling its current pre-grounding fleet of Max aircraft.
• Passengers looking to avoid the jet will be allowed to make free changes, but Southwest says it reserves the right to use the Max for any flight.

Southwest Airlines will resume flying Boeing's 737 Max in March 2021, the airline said Wednesday, two years following the aircraft's worldwide grounding and earlier than previously anticipated.

"The company currently estimates that the Max will return to revenue service in March 2021 after all active pilots have received updated, Max-related training," Southwest said in a regulatory filing. CEO Gary Kelly had previously said in a letter to customers that the aircraft would return "no sooner than the second quarter of 2021."

Southwest had the largest active fleet of 737 Max aircraft before the pandemic thanks to an order for nearly 300 of the Max 8 and Max 9 variants. Now, only 35 will arrive at the airline in 2021.

Despite Southwest's large Max fleet, it will be the last in the US to resume flying the jet as American Airlines will resume flights starting on December 29, 2020, and United Airlines has the aircraft in its schedule for February.

Alaska Airlines has not yet received its first 737 Max but plans to take its first delivery in January 2021 and start service in March on West Coast routes. In Latin America, Brazil's Gol Linhas Aereas and Aeromexico have already begun flying passenger flights with the Max, Aviation International News reported, despite their respective countries approving the aircraft later than the US.

Southwest's return to service plan involves getting the 34 Max aircraft out of storage, updating the faulty software on the aircraft, and re-training pilots to fly the aircraft. Before the grounding, pilots were only required to complete minimal computer-based training but will now be required to undergo simulator training, according to Boeing.

Read more: The 16 most outrageous things Boeing employees said about the company, 737 Max program, and each other in released internal emails

Where the Max will fly for Southwest

Southwest has not announced which routes the Max will initially fly, nor have any flights been given the Max designation in the airline's schedule, according to Cirium data. A Southwest spokesperson told Business Insider in an email that it's still "a work in progress."

For anxious travelers, avoiding the jet might be more difficult on Southwest than it is on other airlines, as the low-cost airline operates an all-Boeing 737 fleet. Therefore, the airline could theoretically use the aircraft on any route.

In the weeks leading up to the aircraft's March 2019 grounding, as many as 163 daily flights were operated with Southwest's fleet of 34 Boeing 737 Max 8 aircraft, according to Cirium. Countless routes across Southwest's network saw the aircraft operate flights from the short Los Angeles-Las Vegas hop to the transcontinental Baltimore-Oakland, California route.

The longer flights in Southwest's network are likely candidates. However, as the airline's flying prior to the grounding shows, long durations aren't a prerequisite. Flights to Hawaii are also likely to see the Max as the long overwater routes were always intended for the aircraft.

How to avoid flying on the jet

Southwest is allowing skeptical passengers to avoid flying on the Max by offering free rebookings to other flights. It's a trend being followed by all US airlines that fly the Max as some flyers are uncomfortable with flying on the plane that's caused two crashes and 346 deaths.

"If a customer chooses not to travel, they also may request a full refund of refundable tickets back to the original form of payment," Southwest's Boeing 737 Max FAQ says.

No fees will be levied as long as the departure and arrival cities remain the same. But Southwest does warn that a Boeing 737 Max can be assigned to any flight, even if marketed as a non-Max flight.

"Please be aware the flight a customer changes to may ultimately depart on a 737 Max 8, as aircraft type always remains subject to change per Southwest's Contract of Carriage," the FAQ continues.

A disclaimer now comes with each Southwest booking that while a non-Max aircraft is currently assigned, the aircraft assignment "subject to change."