United Airlines is planning to offer pre-flight COVID-19 testing for some travelers heading to London from the US.

The trial will run from Nov. 16 through Dec. 11 at the airline’s hub in Newark, New Jersey, to London’s Heathrow Airport.

United fitting the bill for the rapid molecular Abbott ID Now tests on Monday, Wednesday, and Friday departures. But it’s not a requirement.

Travelers who don’t want to be tested will be moved to other flights, “guaranteeing everyone on board other than children under two will have tested negative before departure,” the airline released in a statement.

United joins several other airlines taking advantage of pre-flight testing to help passengers avoid quarantine requirements–which the airline industry says has negatively impacted travelers.

“This patchwork of rules is confusing and discourages travel,” a group of 20 trade groups representing companies from American Airlines to Boeing and Marriott and labor unions reportedly wrote to the Trump administration. “Furthermore, there are alternatives to quarantines, such as testing and screening of passengers at or ahead of departure, that can significantly reduce the risk of importation of COVID-19 and may actually be more effective due to the difficulties in enforcing compliance with quarantine requirements.”

United Airlines officials said it would share feedback from customers to U.S. and U.K. government officials, adding that travel demand has increased when the options to test for the virus before flights are available.