(Bloomberg) -- The largest U.S. pilots’ union is demanding the government force airlines to inform flight crews when coworkers fall ill to Covid-19.

Some carriers haven’t been following Centers for Disease Control and Prevention guidance that they let their their workers know when they’ve been exposed to an infectious disease such as the new coronavirus, the Air Line Pilots Association said in a letter to the Federal Aviation Administration that was made available to Bloomberg News on Thursday.

“Friday’s reports of the death from Covid-19 of an American Airlines flight attendant is especially sobering, and highlights the exigency of taking all needed measures to avoid further contagion of airline crew members,” Joe DePete, president of ALPA, wrote in the letter, which was dated Tuesday.

While large swaths of America are hunkered down in their homes, airlines are continuing to fly and the government plans to require at least a low level of flight service for carriers taking part in a $50 billion bailout program of loans and grants.

“An urgent FAA order, directive or regulatory requirement is needed because ‘guidance’ from the Centers for Disease Control is not mandatory and is not being consistently followed,” DePete wrote.

The union also said that unspecified airlines aren’t following FAA and CDC guidance on how to disinfect aircraft.

“We are aware of airlines claiming to have cleaned aircraft with alcohol-based disinfectants that fail to comply with the minimum 70% alcohol-based solution,” DePete wrote.

At Delta Air Lines Inc., 32 pilots have tested positive for Covid-19, according to the airline’s ALPA local division. The union represents 14,000 pilots at Delta. Delta didn’t immediately respond to a request for comment.

Airlines for America, a trade group representing large carriers, didn’t immediately respond to a request for comment. The FAA also didn’t immediately respond to questions about whether it planned to take additional action.

The CDC guidance for the virus says “employers should inform fellow employees of their possible exposure to Covid-19 in the workplace.” Employees who come in contact with coworkers who have become infected should monitor themselves for symptoms of the disease, CDC says.

ALPA represents more than 63,000 pilots in the U.S. and Canada, including at Delta and United Airlines Holdings Inc.

©2020 Bloomberg L.P.