One impact was a spike in oil prices, which nudged $100 a barrel on Thursday morning (24 February), compared with $63 a year ago. This will filter through to airfares in the months ahead once existing contracts are spent.

Airlines have taken steps to avoid overflying Ukraine. Carriers are particularly cautious after Malaysia Airlines flight MH17 was shot down in 2014 by pro-Russian separatists in eastern Ukraine, killing 298. The aircraft was travelling from Amsterdam to Kuala Lumpur, and the tragedy occurred after some carriers had already chosen to avoid Ukrainian airspace.

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The area in which MH17 was shot down is around 375 miles south-east of Kyiv, where the renewed conflict is centred. Iata said: “Overflight traffic in Ukraine was already considerably reduced since the MH17 incident in 2014. Airlines will be using all available information to make their own risk assessments.

“Safety is always the number-one priority of the industry. To the extent possible, Iata is helping to facilitate the relevant and timely sharing of information with regard to Ukraine and also other potential conflict zones, from government and non-government sources.”

Ukrainian airspace can be easily avoided, despite it being Europe’s biggest country. The picture will become more complicated if, for example, the situation in Afghanistan were to deteriorate. A routing from the UK to Singapore, avoiding Ukraine and Afghanistan, would mean a detour via Egypt’s Sinai peninsula. However, countries like Afghanistan derive considerable income from overfly rights and will want to preserve this.

Carriers have already put contingency plans in place to avoid Ukraine, with radar maps showing few flights operating within its boundaries. British Airways has not operated to Ukraine for several years, and sources confirmed it is not using its airspace.

Etihad is typical of carriers, with a spokesperson confirming: “Etihad Airways has no flights operating to or over Ukraine. Etihad vigilantly monitors global airspace restrictions and threats. The safety and wellbeing of our guests is always Etihad’s highest priority.”

Qatar Airways added: "We don’t overfly Ukraine at the moment for any flights to US or northern Europe."

Any closure of Russia’s vast airspace will have serious consequences for flights from the UK or Europe to Asia, particularly Japan. The cost of increased fuel burn as airlines take longer routes will be passed to consumers, as post-Covid, airlines are in no position to absorb additional overheads.

Finnair is one carrier that uses both Ukrainian and Russian airspace. A spokesperson said: “We stopped flying in Ukrainian airspace on Wednesday. Before that, our flights to Dubai, Gazipasa (Turkey) and Tel Aviv were able to use the airspace in western Ukraine. Now we are diverting the Ukrainian airspace, which lengthens the flight times by five to 15 minutes for each of these flights.”

Finnair’s Asia flights will be affected if Russia imposes restrictions. The spokesperson said: “We have the overflight rights that we need for our Asian operations. Geopolitical tensions have caused speculation before, but we have continued to operate our flights. The shortcut between Asia and Europe is important for many reasons. We see no reason to speculate on this right now.”

Finnair said airspace restrictions “are a part of the everyday life at an airline”, adding there were currently some airspace areas “that we do not use”.

Russia’s aggression has already decimated Ukraine’s main airline. Ahead of the invasion, Ukraine International Airlines (UIA) reduced its flying programme and moved aircraft out of the country. Eurocontrol data showed UIA had slowed its operation to such an extent that Ryanair and Wizz Air were the dominant carriers to the country but both have now ceased operations there.

Ukraine International, which normally operates to Gatwick, has had to renegotiate insurance and obtain consent from aircraft lessors. As a result, seven Boeing 737s have been removed to Spain. UIA said: “Due to a number of factors, including the revision of insurance rates and the low season, UIA has decided to temporarily reduce the number of aircraft to 13.”

A Gatwick spokesperson said: "Scheduled flights into Gatwick from Kyiv have not operated for the last week, and the airspace is closed, so further commercial flights are not very likely.  
 
"We’re still assessing whether there will/will not be any impact more broadly, for example on neighbouring countries."