Airlines are bracing for potentially lengthy blockages of key east-west flight corridors after the European Union and Moscow issued tit-for-tat airspace bans. The United States and Canada have also taken similar action in response to Russia's invasion of Ukraine.
The unprecedented steps are aimed at pressuring Russian President Vladimir Putin to end his invasion of Ukraine, the biggest attack on a European state since World War Two.
Russia has retaliated by banning airlines from dozens of countries including all 27 members of the European Union after EU ministers agreed to refuse entry to Russian airplanes including the private jets of the country's oligarchs.
Delays and detours
The sanctions have sparked flight cancellations and costly detours, denting the industry's pandemic recovery and dealing a blow to the mainly Ireland-based leasing industry which was ordered to stop doing business with Russian airlines.
Without access to Russia's airways, experts say carriers will have to divert flights south while also avoiding areas of tension in the Middle East.
Recent flights from European and US airlines to Asia have been forced to take major detours.
Some airlines operating the same service as each other, have flown very different routes due to the bans. For example, Asian airlines can fly across Russia to Europe - though many have stopped doing so since the invasion as a precautionary step - but European airlines cannot.
The examples below show how much these routes can vary even though flown on the same day, adding hours to flight times.
Impact on Russian flights
Russian commercial flights have also been affected. Russia's Aeroflot said it has cancelled all flights to European destinations until further notice and has also cancelled flights to some central American destinations due to the closure of Canadian airspace.
Some flights which have operated between Moscow and Central America have had to avoid Greenland, Canada and the US, adding flight time to the journey.
Surrounding countries have closed their airspace to Russian aircraft but flights at Russia's Kaliningrad are able to continue operating through a narrow corridor of airspace. Due to the legal definition of national airspace, nations cannot ban aircraft more than 12 nautical miles beyond the coastal baseline.
Kaliningrad is a Russian region that lies on the Baltic Sea between EU members Lithuania and Poland. Moscow captured the region from Germany toward the end of World War Two.
The map below shows the areas out of bounds around the Baltic Sea and how Russia has been operating flights through the area. Aircraft are unable to exit the area to the West and North due to restricted airspace but Kaliningrad remains connected to mainland Russia.
Airspace around the Baltic Sea
Empty skies over Ukraine
Data from flight-tracking service FlightRadar24 shows empty skies over Ukraine and parts of Russia. Ukraine International Airlines sent part of its fleet to safety abroad before the conflict. However, many flights were operating out of Kyiv running up to Russia's invasion on 24 Feb.
Airlines skirted the whole country in crowded corridors to the north and west, leaving a hole in the aviation map.
Civilian flight activity
The maps below show passenger or cargo flights in the area. Reuters analysed flight path data from FlightRadar24, filtering those with flight numbers, indicating scheduled private, commercial or cargo flights.
While Ukraine's airspace has been relatively quiet amid the crisis with Russia, a remotely piloted US military vehicle called the RQ-4 Global Hawk took the spotlight, flying over the country in circles for hours at a time.
Over the past month, two of the spy planes have travelled on regular missions from the Mediterranean Sea to Ukraine, where they have navigated in repeated loops in the north and the east, according to Flightradar24.
The drones' high-altitude, long-distance flights have coincided with a military build-up by Russia along the Ukrainian border and a flurry of diplomacy among leaders of the United States, Europe and Russia to avert war.
At times, the two planes have been the only active aircraft publicly visible over eastern Ukraine. Aviation watchers have taken note, speculating that the United States is making its presence known in a show of force.
"With these types of flights, leaving the transponder on is a conscious decision," said Ian Petchenik, communications director at Flightradar24.
The maps below show tracked military, private and unidentified aircraft in the area.
Military and unidentified aircraft
These flight paths have no flight numbers assigned but some have information on aircraft type
Data from travel consultancy ForwardKeys, shows that flight cancellations to and from Russia spiked after the invasion of Ukraine. On 25th February, the day after the start of the invasion, every booking that was made for travel to Russia was outweighed by six cancellations of pre-existing bookings.
The highest cancellation rates, in order of volume, were Germany, France, Italy, Britain, India and Turkey.
The invasion also triggered a collapse in the market for Russian outbound travel. Destinations that suffered the highest immediate cancellation rates from Feb. 24 to 26, were Cyprus, Egypt, Turkey, the UK, Armenia, and Maldives.
"The Russian tourism economy was beginning to revive from the pandemic, and it will now experience another substantial blow. There will also be serious impacts on destinations that depend heavily on Russian visitors," said Olivier Ponti, VP Insights of ForwardKeys, in a recent report.
"The outbreak of war always has a hugely damaging impact on the travel industry and that is what we are seeing here."