Social distancing sign is displayed at a check-in area for Southwest Airlines Co. at Los Angeles International Airport (LAX) on an unusually empty Memorial Day weekend during the outbreak of the coronavirus disease (COVID-19) in Los Angeles, California, U.S., May 23, 2020. REUTERS/Patrick T. Fallon 

Air travelers wear face masks waiting to board a Southwest Airlines flight as the spread of coronavirus disease (COVID-19) continues, at Oakland International airport in Oakland, California, U.S., April 9, 2020. REUTERS/Shannon Stapleton 

An aerial photo shows Gol Airlines, Southwest Airlines and Alaska Airlines Boeing 737 MAX aircraft at Boeing facilities at the Grant County International Airport in Moses Lake, Washington, September 16, 2019. REUTERS/Lindsey Wasson 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake TPX IMAGES OF THE DAY 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake TPX IMAGES OF THE DAY 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A Southwest Airline Boeing 737 MAX 8 aircraft lands at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft (top) are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A Southwest Airlines Boeing 737 MAX 8 lands to join a number of other grounded Southwest Airlines Boeing 737 MAX 8 aircraft at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, U.S., March 26, 2019. REUTERS/Mike Blake 

A Southwest Airlines Boeing 737 MAX 8 aircraft is pictured in front of United Airlines planes, including Boeing 737 MAX 9 models, at William P. Hobby Airport in Houston, Texas, U.S., March 18, 2019. REUTERS/Loren Elliott 

A Southwest Airlines Boeing 737 MAX 8 aircraft is pictured in front of United Airlines planes, including Boeing 737 MAX 9 models, at William P. Hobby Airport in Houston, Texas, U.S., March 18, 2019. REUTERS/Loren Elliott 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft sits at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

Southwest Airlines Co. Boeing 737 MAX 8 aircraft sit next to the maintenance area after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis to the maintenance area after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis to the maintenance area after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis to the maintenance area after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis to the maintenance area after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

Southwest Airlines Co. Boeing 737 MAX 8 aircraft sit at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest Airlines Co. Boeing 737 MAX 8 aircraft taxis after landing at Midway International Airport in Chicago, Illinois, U.S., March 13, 2019. REUTERS/Kamil Kraczynski 

A Southwest airplane sits on the tarmac in Austin, Texas, U.S., March 12, 2019. REUTERS/Lucy Nicholson 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 15, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 15, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

An A380 Airbus superjumbo sits on the tarmac where it is dismantled at the site of French recycling and storage aerospace company Tarmac Aerosave in Tarbes, southwest France, February 14, 2019. Airbus announced plans to halt production of the slow-selling model of airliner. REUTERS/Regis Duvignau 

FILE PHOTO: Southwest Airlines Chairman Herb Kelleher (C) testifies during a Senate Commerce, Science, and Transportation Subcommittee on Aviation hearing on the Wright amendment on Capitol Hill in Washington, November 10, 2005. REUTERS/Jim Young/File Photo 

FILE PHOTO: Southwest Airlines Chairman Herb Kelleher (C) testifies during a Senate Commerce, Science, and Transportation Subcommittee on Aviation hearing on the Wright amendment on Capitol Hill in Washington, November 10, 2005. REUTERS/Jim Young/File Photo 

U.S. President Donald Trump shakes hands with pilot Tammie Jo Shults, who safely landed the damaged Southwest Airlines Flight 1380 in in Philadelphia, during a meeting with passengers and crew members at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

U.S. President Donald Trump welcomes the crew and passengers of Southwest Airlines Flight 1380 at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

U.S. President Donald Trump welcomes the crew and passengers of Southwest Airlines Flight 1380 at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

U.S. President Donald Trump welcomes the crew and passengers of Southwest Airlines Flight 1380 at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

U.S. President Donald Trump shakes hands with pilot Tammie Jo Shults, who safely landed the damaged Southwest Airlines Flight 1380 in in Philadelphia, during a meeting with passengers and crew members at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

U.S. President Donald Trump shakes hands with pilot Tammie Jo Shults, who safely landed the damaged Southwest Airlines Flight 1380 in in Philadelphia, during a meeting with passengers and crew members at the Oval Offices of the White House in Washington, U.S., May 1, 2018. REUTERS/Carlos Barria 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela TPX IMAGES OF THE DAY 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

Emergency personnel monitor the damaged engine of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

A truck drives baggage carriers towards Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

An airplane passes in front of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela 

An airplane passes in front of Southwest Airlines Flight 1380, which diverted to the Philadelphia International Airport this morning after the airline crew reported damage to one of the aircraft's engines, on a runway in Philadelphia, Pennsylvania U.S. April 17, 2018. REUTERS/Mark Makela