A mutant strain of the dreaded Coronavirus that has been fast spreading in the United Kingdom (U.K.) has sent shockwaves around the world, forcing countries to halt international flight operations to the island nation. On Monday, India, too, took the call to suspend all international flights—starting from December 22, 11:59 pm, till December 31—to the U.K., a country that’s home to a sizeable Indian diaspora for whom annual visits to the sub-continent are a must.

“Diwali, Christmas, New Year, these are festivities for which the Indian diaspora from the U.K. travel to India. Add to that: the winter wedding season in the country,” says Vinamra Longani, head of operations for Sarin & Co., an Indian law firm specialising in aircraft leasing and finance. Even though traffic is more from London to India, passenger traffic between Mumbai and London is the second highest, after Mumbai and Dubai, according to data shared by Chhatrapati Shivaji Maharaj International Airport, in Mumbai.

To be sure, scheduled international air travel to and form India continues to remain suspended. But the Indian government has been slowly opening up international air travel by way of repatriation flights and allowing flight operations under an air bubble agreement. In the latter, India has signed agreements with over 20 countries allowing for the movement of passengers to and from that country only. And since, direct flights between India and the U.K., and the U.S. have gained traction.

According to Longani, countries that have a large Indian diaspora are seeing a good amount of VFR (visiting, friends and relatives) traffic movement. “That is why the two British airlines (British Airways and Virgin Atlantic) have increased frequencies [to India], and Vistara from our side is operating a daily flight from New Delhi to London, with plans to start from Mumbai next year,” says Longani. “London has always been a key market,” adds Jitender Bhargava, the former executive director of Air India. Interestingly, the country’s flag carrier began its international operations with flights to London in 1948, and continues to be a dominant player on the route.

On the other hand, U.S.-based United Airlines recently launched a new daily non-stop service between New Delhi and Chicago, taking its tally to four daily non-stop flights from India. It also plans to introduce a new daily non-stop service between Bengaluru and San Francisco commencing May 8, 2021. Air India has already launched such a flight, connecting the two tech hubs.

Given the restrictive nature of the air bubble agreements—providing passengers only direct flights and not layover flights—none of the West Asian airlines can ferry any of the U.S. and U.K. bound international traffic to and from India. Hence, whatever traffic there is between India and the U.K., and U.S. has been served on a platter to airlines from both countries. “Airlines want to operate on routes where they can at least recover their operating costs,” says Longani, adding that the VFR traffic between Indian and U.K. addresses that concern for airlines.

Now, with a new Coronavirus strain taking the U.K. by storm, all bets on the India-U.K. air bubble are off. “Vistara will comply with the government’s decision to suspend all flights originating from the U.K. to India,” a spokesperson of Vistara informed Fortune India. “In order to minimise inconvenience to our customers, we will enable one-time free-of-charge rescheduling of affected bookings to any date until December 31 2021,” the spokesperson added. Vistara was to launch a Mumbai to London flight from January 16, but the spokesperson confirmed that “it now depends on the resumption of [air travel] operations.”

Interestingly, another Indian carrier, SpiceJet, which had plans to fly to London under the air bubble agreement, had called off its bet much earlier. The budget airline had planned to connect New Delhi and Mumbai with London’s Heathrow airport starting December 4, but didn’t go-ahead as the U.K. went into lockdown in early November.

“Nine months ago China was an epicentre, and all countries withdrew flights to and from China. Now with a new strain in the U.K., an unknown commodity, no one is sure whether it can be countered by the vaccines [that have been given approvals],” says Bhargava. Suspension of flights to the U.K., he says, is a decision that all countries have taken in national interest. “You don’t want people to come and infect [others], leading to more lockdowns.”

Ever since India allowed repatriation flights and put in place air bubble agreements, Dubai, London-Heathrow, Newark (U.S.), Doha, and Abu Dhabi have emerged as the top five international destinations for passengers flying out of India’s financial capital Mumbai. According to Chhatrapati Shivaji Maharaj International Airport, in Mumbai, Dubai emerged as the route with the highest passenger traffic catering to over 267,600 passengers; followed by London-Heathrow at over 89,800 passengers, Newark with 80,800 passengers, Doha with 58,200 passengers and Abu Dhabi with 39,400 passengers approximately. And it's no surprise that Dubai tops the charts.

“The [travel] requirements that Dubai has put in place is by far the most practical one for anybody who wants to get away for a holiday at this point in time,” says Longani, who himself is looking at a holiday in the West Asian city. “All you got to do is have a negative RT-PCR report, which has to be done 72 to 90 hours before departure. On arrival in Dubai, you get a test done and if you're negative, you're good to go. Compare that to some of the other countries who expect you to be in 14 days of self isolation and quarantine,” he points out.

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