Southwest Airlines (LUV -2.39%) said Wednesday that, although it is currently burning through nearly $20 million in cash per day, it has enough money in the bank to last at least two years, fresh evidence to support the argument that the airline is among the most likely to survive the COVID-19 crisis.

Southwest in a regulatory filing said it "continues to experience significant negative impacts to passenger demand and bookings" due to the pandemic, which has caused Southwest and other airlines to scramble to cut costs and raise cash.

A 737 in Southwest colors in flight.

Image source: Boeing.

So far in 2020, Southwest has raised about $16.7 billion via new debt, aircraft sales, an equity sale, and government assistance through the CARES Act.

After experiencing more cancellations than bookings in March and April, Southwest has seen "modest improvement" beginning in May. Nevertheless, operating revenue is still expected to be down at least 85% year over year in May and will be down 65% to 70% for the second quarter. Investors remain nervous that the rebound will be short-lived, with a return to March lows possible if new COVID-19 cases continue to increase or a second wave of the pandemic arrives in the months to come.

Southwest said it has cash and short-term investments totaling $13.9 billion, including government assistance, which is about 24 months of liquidity at current burn rates. Even if conditions worsen, Southwest still has levers to pull: The airline estimates it has about $12 billion in unencumbered assets, including about $10 billion in aircraft, that it could borrow against.

Southwest has parked 140 aircraft, including its 34 Boeing 737 Max aircraft that remain grounded by regulators. The airline said it "continues to plan for multiple scenarios for its fleet" for the remainder of 2020, subject to demand trends.