Britain could restart leisure travel with the U.S. next month as part of a plan to reopen its borders, according to the head of London’s Heathrow airport.

Progress on Covid-19 vaccinations in the two countries could allow the U.S. to be included on the so-called Green List of countries from which people will be able to travel to Britain without quarantine, Heathrow Chief Executive Officer John Holland-Kaye said in an interview Thursday.

Locations likely to feature on the list include Singapore, Hong Kong, Australia, New Zealand, Israel and Iceland, plus some Caribbean destinations, the CEO said. Heathrow has been in constant communication with the government over the impact of the pandemic as well as plans for a resumption in travel.

A restart of U.S. services would come as a huge boost for Heathrow, which relies on the market for 20% of its traffic. The airport, Europe’s busiest prior to the pandemic, said passenger numbers remained stuck at just 9% of usual levels in the first quarter as current curbs limit operations at carriers such as British Airways and Virgin Atlantic Airways Ltd.

Greek, Spanish Islands

Holland-Kaye said he expects Prime Minister Boris Johnson’s government to publish the Green List of places from which people can travel to Britain without quarantining as early as the end of next week.

The government has targeted a reopening of travel as soon as May 17, though it’s not clear to airlines how extensive it will be because the category list hasn’t been released. Arrivals from places marked green will still require a minimum of two Covid-19 tests, but those listed as amber or red will also face quarantines.

Some short-haul leisure destinations could be green-listed, but most likely only to island sunspots such as Spain’s Balearics and Canaries, Holland-Kaye said. Mainland Spain and Greece may not feature until June and July respectively.

The U.K. will confirm by early May if international travel can resume on May 17, and which countries will fall into each category, a Department for Transport spokesman said in an email.

One Direction

While a full deal with the U.S. might be difficult to reach in time for the mid-May target, a unilateral reopening could allow Americans to fly into the country for business and leisure trips, Holland-Kaye said. In this scenario, Brits seeking to go to the U.S. would have to wait for the Biden administration to reciprocate.

Bloomberg reported last week on bilateral talks between the U.S. and U.K. transport secretaries on a potential travel corridor.

Any concerns about high infection rates in some U.S. states should dissipate by the end of next month as inoculations make further progress there, Holland-Kaye said, so that the U.K. “should be comfortable that the U.S. is a low-risk country.”

That would allow a full opening of trans-Atlantic travel in time for the main holiday period starting in June. The European Union, which is behind the U.S. and U.K. in vaccinations, is also rushing to get a system in place that will allow for cross-border travel.

Heathrow said earlier that it may attract only 13 million passengers this year if travel markets aren’t reopened, increasing to 36 million in a best-case scenario. The hub lured 81 travelers in 2019, a figure that fell to 22 million last year.