The lawsuit, filed by the Allied Pilots Association in Dallas County on Thursday, is seeking a temporary restraining order to stop all services flying out of and into China, according to a press release.
American Airlines currently operates approximately 56 monthly flights between Dallas-Fort Worth International Airport and airports in China, the lawsuit said.
The airline, which is also based in Fort Worth, announced on Wednesday that it would suspend flights between Los Angeles International Airport and China but not until Feb. 9.
American Airlines crewmembers working a trip to China are required to be on the ground for approximately 32 hours between flights to comply with federal rest regulations, the union said.
The APA said it filed the lawsuit due to the “serious, and in many ways still unknown, health threats posed by the coronavirus.”
“The safety and well-being of our crews and passengers must always be our highest priority — first, last, and always,” APA President Capt. Eric Ferguson said in the press release.
“Numerous other major carriers that serve China, including British Airways, Air Canada, and Lufthansa, have chosen to suspend service to that country out of an abundance of caution. The APA leadership has asked American Airlines management to follow suit, but to date they have not canceled any U.S.-China flights. We are therefore compelled to seek injunctive relief.
“We estimate that as many as 300 passengers and crew travel to DFW alone from Chinese cities on each American Airlines flight. To us, that level of risk is unacceptable,” Ferguson added.
“Due to the known and unknown risks associated with traveling to China right now, concurrent with the filing of our lawsuit, we are directing all American Airlines pilots assigned to flights between the United States and China, other than those on return trips to the United States, to decline the assignment.”
In a statement provided to Fox News on Thursday, American Airlines said that it was "aware" of the lawsuit's filing and would "continue to monitor the situation," regarding the coronavirus outbreak.
"We are aware of the filing. We are in close contact with the Centers for Disease Control and Prevention (CDC) and global public health officials to make sure we are taking all necessary precautions for our customers and team members," the statement said. "Yesterday, American announced the suspension of travel between LAX and Shanghai Pudong Airport (PVG) as well as LAX and Beijing Capital International Airport (PEK) from Feb. 9 through Mar. 27, 2020. We will continue to monitor the situation and make any updates as needed."
A request by Fox News for comment from the Allied Pilots Association were not immediately returned.
The World Health Organization on Thursday declared the new coronavirus outbreak a global emergency amid the recent jump in the number of infected patients.
"The main reason is not what is happening in China but what is happening in other countries," WHO chief Tedros Adhanom Ghebreyesus announced at a news conference in Geneva, Switzerland.
"Our greatest concern is the potential for the virus to spread to countries with weaker health systems, and which are ill-prepared to deal with it," Ghebreyesus added.
Fox News’ Vandana Rambaran contributed to this report.