Russia's invasion of Ukraine and aviation bans are creating huge no-go areas in the sky, with major implications for long-haul carriers that normally criss-cross the skies of Eastern Europe en route to Asia.
As of Sunday, many European countries announced that they were closing their airspace to Russian airlines and aircrafts, including Germany, Italy, France and Spain.
European Commission President Ursula von der Leyen confirmed on Sunday that the European Union is shutting down the EU airspace to Russia.
Canada also announced that the country is closing its airspace to Russia as well on Sunday.
The United Kingdom and Russia have banned each other's aircraft from overflying or landing on their territories. Other bans have begun to follow, with Poland and the Czech Republic both restricting access to Russian aircraft on Friday.
All this could have significant consequences for passengers, airlines and the cost of flying if Europe and Russia revive the Cold War era, when sky routes were diverted around an Iron Curtain that extended into the sky.
Apart from punching a significant hole in the aviation traffic map of Eastern Europe, disruption of long-haul traffic is minimal so far. Even Russian aircraft using international airspace over the Atlantic are unaffected, despite the area being managed by air traffic services based in the UK.
But what about flights to East Asia? During the frostiest days of the Cold War, avoiding the Soviet Bloc meant flying north around Greenland to Alaska, refueling in Anchorage, and then around the Bering Straits to reach Japan. China-bound flights skirted the Black Sea and Caucasus, avoiding Afghanistan and entering China across Central Asia.
We're not there yet. And perhaps thanks to the range of modern aircraft, such steps won't be needed.
The effects on already Covid-impacted commercial airlines and their passengers will at this point be relatively limited if the bans stay between Russia on one side and the UK, Poland and Czech Republic on the other. Equally, the situation could easily escalate.
"Because of Russia's geographic scale, overflights from airlines all over the world pass through Russian airspace each day," Mikael Robertsson, co-founder of aircraft tracking service Flightradar24, tells CNN. "From the UK, normally about a dozen flights each day pass through Russia en route to places like Hong Kong and India.
"From the EU, hundreds of flights each transit through Russia en route to destinations in Asia. And from the US, most cargo traffic between the US and Asia passes through at least a small portion of Russian airspace. Pre-Covid, the numbers were even greater, especially from the UK, but long-haul passenger flights have yet to really recover."
In terms of flight services, the only Russian passenger airline serving the UK is Aeroflot. The UK's largest carrier, British Airways, served Moscow before the war. BA's parent company, International Airlines Group, has announced that its airlines will not be overflying Russian airspace.
At the beginning of the conflict, the US Federal Aviation Administration issued NOTAM (Notice To Air Missions) instructions to US carriers to avoid operations in areas that include all of Ukraine, Belarus and western parts of Russia. Few US passenger airlines overfly Russia, with nonstop flights to India slow to restart after aviation's Covid shutdowns.
British Airways' and Virgin Atlantic's Asian networks, meanwhile, have largely not been restored after being suspended because of the Covid-19 pandemic. The relatively closed borders of Japan, China and other countries to international arrivals for public health reasons mean that passenger services by UK airlines remain limited.
Read more about how worldwide air traffic could be impacted by the Russian invasion of Ukraine here.
CNN's Al Goodman, Paula Newton, Martin Goillandeau, Hada Messia and Chris Liakos contributed to this report.
