Delta Air Lines will lower its passenger capacity by 40% to deal with a nosedive in travel demand because of the widening coronavirus outbreak. The cut is the largest in the carrier's history, surpassing reductions that were made after the September 11 terror attacks.

"The speed of the demand fall-off is unlike anything we've seen – and we've seen a lot in our business," CEO Ed Bastian said in a memo to Delta's 90,000 employees on Friday.

"We are in discussions with the White House and Congress regarding the support they can provide to help us through this period. I'm optimistic we will receive their support," he said, while adding that the airline "can't put our company's future at risk waiting on aid from our government."

Get Breaking News Delivered to Your Inbox

Bastian also said he would give up his salary for the rest of the year, CNBC reported. Delta's stock price has fallen nearly 40% over the last month, joining other airlines whose shares have plummeted during the growing public health crisis.

The plunge in travel associated with the coronavirus is hitting airlines hard. American Airlines is facing a credit crunch and will need to raise $3 billion in the next few days to cover its bills, according to one estimate. WestJet, a discount Canadian carrier, could lay off as much as half of its staff, The Canadian Press reports.

The U.S. this week announced a ban on some travel from Europe, which is set to take effect Friday night. Denmark has followed suit, closing its borders to non-citizens for a month, starting Friday.