Southwest Airlines (LUV -0.54%) has updated its COVID-19 policy limiting sales to ensure the middle seat stays open through at least Sept. 30, 2020. Southwest customers may still choose their own seats, and the company will not block or direct seating, it said. Southwest also introduced a new "Customer Health Declaration" that passengers will be required to acknowledge during online check-in. 

Other airlines are also attempting to gain customer trust in the safety and cleanliness of air travel during the pandemic. United Airlines Holdings (UAL -2.52%) received criticism when some flights were full after passengers expected social distancing to be enforced. United revised its policy to now contact customers approximately 24 hours prior to a "fairly full" flight, so they can adjust travel plans with no change fee or receive credit for a new flight.

airplane cabin full of passengers

Image source: Getty Images.

United has also announced that it will "strengthen" mandatory mask policies to protect passengers and employees. The airline said that beginning tomorrow, June 18, any passenger that doesn't comply with the mask policy onboard a flight will be put on an internal travel restriction list. These individuals will be banned from flying on the airline for a period of time determined after an investigation of the incident.

Delta Air Lines (DAL -2.62%) also recently reiterated its mask policy, saying that customers will not be allowed to board without one and that those who do not comply will risk losing future travel privileges on the airline.

Airlines have also announced upgraded cleaning policies, including United creating its United CleanPlus arrangement with Clorox (CLX 1.24%) and the Cleveland Clinic.