With the European Union having a travel ban for Americans and the U.K. imposing a 14-day quarantine on travelers from the United States, travel to and from the U.S. to Europe is struggling during the pandemic.

The leaders of major airlines have written a letter to officials in the U.S. and European Union asking for a COVID-19 testing standard that would allow people to travel safely over the Atlantic.

American, United, Lufthansa, British Airways and other carriers want to establish a testing program that will “permit services to resume without quarantine requirements or other entry restrictions.”

It is not known whether the testing would take place at airports or if a negative test prior to travel would be the standard.