The Adolfo Suarez Barajas Airport in Madrid is the second largest by size in continental Europe.

In 2019, nearly 62 million passengers passed through the airport. Back then, the owners had planned to expand capacity, that was until the pandemic hit.

Since then recovery has been slow. The latest figures from IAG - the umbrella group for Spain's national carrier Iberia, British Airways and Aer Lingus - included a forecast of a $3bn loss for 2021.

That would still represent nearly a 60 percent improvement year-on-year.

The group can also boast an increase in passenger numbers, up from the previous quarter, although they are still less than half of pre-pandemic figures.

The relaxation of restrictions has helped, but travel in and out of the UK has until recently been stifled due to the high cost of mandatory PCR testing.

Business travellers make up only an eighth of all passengers, but often account for up to 75 percent of airlines' profits. So getting these passengers back on board is essential for a return to airline profitability.

CGTN Europe spoke to one business class traveller about to fly to London.

"Zoom calls, Microsoft Teams, everyone is keen not to travel so much any more. It saves costs, it's more efficient. So not everyone travels. However, I have just come back from a meeting and you find that the in-person relationships are so much better."

Another female traveller said: "I think being able to have meetings via video and remote work has affected a lot of business class flights. Companies don't send their workers that frequently to have meetings outside of Spain."

IAG is predicting an upward passenger spike of up to 60 percent for the final quarter of the year, helped by the reopening of the transatlantic corridor with the U.S..

Higher fuel costs may dampen that enthusiasm, but there is cautious optimism on what is likely to be a long road back to normality for the airline industry.