Delta Air Lines on Monday said it will allow travelers holding tickets to any destination in March and April to change or cancel their flight without paying a hefty change fee, regardless of when they bought the ticket.

The broad fee waiver, the first by a major U.S airline, provides travelers holding nonrefundable tickets more flexibility as trips are canceled due to the coronavirus crisis.

"As concerns continue about the coronavirus known as COVID-19, we are doing everything we can to ensure the safety and security of our customers and employees,'' Delta said in statement on their website announcing the policy. "We have adjusted flight schedules to affected areas, waived many change fees and are working with customers to adjust travel plans, using relationships with other airlines when needed.''

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The move was matched by United late Monday and American early Tuesday.

The airlines had been sharply criticized this month for only waiving change fees for travelers buying new tickets, a policy designed to boost sagging ticket sales. Southwest is the only major airline that routinely does not charge a change fee.

Last week, Sen. Richard Blumenthal sent letters to the CEOs of Delta, United and American, asking them to waive change and cancellation fees for all flights not just flights purchased in March.

Blumenthal said the fee waivers issued by American, Delta and others were "welcome steps'' but too limited because they only cover travelers buying new plane tickets. Travelers bought tickets for spring break last fall would not be covered, for example.

"Airlines should enable consumers to adjust their travel plans – regardless of when those decisions are made or when a passenger’s ticket was purchased,'' he said in the letter to American CEO Doug Parker.

Delta changed its policy late last week to cover international flights, regardless of when the flight was booked, but not domestic flights.

The waivers announced Monday and Tuesday covers flights to all of the airlines' destinations for passengers with tickets for travel through April 30 that were purchased before early March. The airlines have separate change fee waivers for tickets purchased in March and for travel to Asia and Italy so travelers need to check their airline's website for details.

Travelers who know the dates they want to change to can do do without paying change fees that start at $200 per person. Any fare difference since the flight was booked will apply.

Passengers who don't know when they want to travel again, can cancel their flight and receive a voucher for the value of their ticket. They will not have to pay a change fee when they redeem the voucher.

Travelers with tickets for travel in May or beyond that were purchased last year or before early March will have to pay a change fee unless the airlines extend the policy.

Lindy Lin, a federal investigator who lives in Los Angeles, was hopeful American and other airlines would match Delta's move.

Lin is supposed to fly to Miami this weekend for her bachelorette party but the group decided they don't want to fly because some members have kids or frail relatives at home.

The party is being moved to Palm Desert, California, a 2½ hour trip by car.

Lin said she was having trouble getting American to waive the change fee on her $430 ticket from Miami to Los Angeles.

"They want to take $200 of that,'' she said, leaving her with just a $230 ticket. "How absurd.''

Taking a cue from Blumenthal's plea to airlines, Lin started a Change.org petition to get American to change its change fee policies during the outbreak.