Air Canada tried again to persuade the government of Justin Trudeau to ease restrictions on travel, pointing to policy shifts in other nations where the Covid-19 pandemic has shown signs of improvement.

In a letter to Canadian Transport Minister Marc Garneau and other cabinet members, the airline’s chief medical officer suggested loosening quarantine requirements through “a science-based approach” to strike a balance between economic and public health concerns. In following some countries in Europe and Asia, Canada would enable a “measured restart of aviation,” he said.

“Canada has made virtually no change to its quarantine restrictions since mid-March, despite continuing improvements containing the spread of the virus both in our country and in many others,” Jim Chung wrote. “This is severely impacting Air Canada, our customers and employees as well as an overall recovery.”

The publicly-shared letter is the latest attempt by the country’s biggest air carrier to sway Trudeau, who has resisted crafting specific rescue plans for struggling airlines. Last month, Chief Executive Officer Calin Rovinescu called Canadian rules “disproportionate” for a country where the pandemic has been easing.

Garneau’s office didn’t immediately respond to a request for comment.

The worst of the pandemic seems to have passed for now in Canada, where provincial governments are weeks into reopening their economies, while urging citizens to wear masks to avoid a second wave. The country has suffered nearly 8,800 virus deaths so far, but only about 650 in the past month.

While the border with the U.S. remains closed, the European Union has put Canada on a list of exempt countries, a measure Canada has not reciprocated. Trudeau’s government has extended rules prohibiting most foreign nationals from entering as tourists. Anyone entering the country must quarantine for 14 days.

Air Canada said it’s not suggesting reopening the border with the U.S., where the Covid-19 situation is still critical. Yet Chung said Canada could establish a list of exempt countries deemed low-risk, from where travelers wouldn’t need to self-isolate upon arrival.

For countries that don’t qualify, Canada could use a test-based model that might help shorten quarantine requirements. Versions of that have been used by countries including Iceland and South Korea, Chung said.