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American Airlines, responsible for about 70% of the traffic at Philadelphia International Airport, is slashing both international and domestic flights as coronavirus spreads, CNBC reported.

The airline, which serves 600,000 passengers a day worldwide, will cut 10% off its summer international flying — including a 55% cut to trans-Pacific flights, according to CNBC.

Per its website, American Airlines is also suspending flights from Philadelphia to Rome, effective immediately through the end of April.

United Airlines will cut domestic flights by 10% and international flights by 20% next month, and executives are planning “similar reductions” in May, the airline said Wednesday, underscoring the drop in demand for air travel given the worldwide spread of coronavirus.

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Many major U.S. firms have paused non-essential travel, scientific conferences have been canceled, and some would-be passengers have balked at flying during a time of high uncertainty.

"We sincerely hope that these latest measures are enough, but the dynamic nature of this outbreak requires us to be nimble and flexible moving forward in how we respond," United chief executive Oscar Munoz and President Scott Kirby said in a statement.

The airline is seeking volunteers at the company to take unpaid leaves of absence, and is instituting a hiring freeze "except for roles that are critical to our operation," the executives said, noting that management and administrative salary increases are also being delayed.

United said "given the high level of uncertainly regarding travel," no change fees will be charged for any domestic or international tickets purchased between March 3 and March 31.

United pointed to sharp cutbacks in flights by other airlines, saying that Cathay Pacific "had canceled more than three-quarters of its weekly flights in March," and British Airways is making deep cuts later this month given the "large decline" in ticket purchases.

Delta, the world’s biggest airline by revenue, said it will cut international flights by 20% to 25% and reduce U.S. flying by 10% to 15%, roughly matching cuts previously announced by United Airlines. CEO Ed Bastian said the airline is “prepared to do more” if the outbreak grows.

“If you are scared of flying, you are probably scared at any price,” said Delta President Glen Hauenstein.

The airline is cutting spending, including putting a freeze on hiring, delaying voluntary pension contributions and suspending share buybacks.

American Airlines announced it will cut international flying by 10% this summer and reduce U.S. flying by 7.5% in April. It has delayed training of new pilots and flight attendants.

United said it has arranged $2 billion in additional bank borrowing to preserve financial flexibility — raising liquidity from $6 billion to $8 billion.

The airlines are also evaluating their assets — planes, engines, spare parts and other items — to determine what could be used as collateral for more borrowing, if that is needed.

"Airlines are experiencing double-digit declines in demand, and on many routes traffic has collapsed," Alexandre de Juniac, director general of the International Air Transport Association, said in a statement. The group noted that China's Ministry of Transport "reported an 80% annual fall in volumes in late January and early February."

Globally, travel demand still rose 2.4% in January, compared with the same period the year before, the group said. Those figures only partially reflected the impact of travel restrictions, some of which did not begin until late January, the group said. Still, it marked the lowest increase in demand for travel since April 2010, during "the volcanic ash cloud crisis in Europe that led to massive airspace closures and flight cancellations."

Travel in December, by contrast, was up 4.6% from the same month the previous year. The signs of slowdown reflect the "tip of the iceberg in terms of the traffic impacts," de Juniac said.

The U.S. Travel Association reiterated that the outbreak is "expected to disrupt inbound travel, particularly from fast- growing Asian markets, over the coming months."

United is cutting back flights to Asia and suspending its trips to Hong Kong, Beijing, Shanghai and Chengdu, in Sichuan province.

United said its "aggressive" actions are designed to minimize impacts as much as possible, for example by cutting the weekly frequencies of certain flights, targeting routes that have alternatives "via other United hubs," and delaying the start of seasonal travel. The airline said it would not completely cut off flights to any of its domestic destinations.

United said the specific schedule changes would be made public Saturday.

David Keonig of the Associated Press, and Michael Laris of the Washington Post contributed to this report.