French-Dutch airline Air France-KLM and British Airways-owner IAG on Friday returned to profit for the first time since the outbreak of the COVID-19 pandemic as demand for European flights between April and June boosted its battered finances.

Air France however said its performance was hampered by a global shortage of airport staff.

"The strong recovery we see this summer is putting the entire aviation industry to the test," said chief executive Benjamin Smith.

"While Air France-KLM had prepared for close to pre-pandemic demand levels, our airlines are not immune to the major operational challenges taking place around the world."

The carrier said it booked net profit of 324 million euros ($330 million) in the period from April to June from a loss of 1.5 billion euros in the corresponding period a year earlier.

The last time Air France-KLM was in profit was in the summer of 2019 before the COVID-19 pandemic shutdown most air traffic worldwide and caused the French-Dutch airline to run up losses of some 11 billion euros over two years.

The group said it transported 22.8 million passengers in the April-June period, three times more than in the year-earlier period.

Group sales soared by 144% to 6.7 billion euros, the statement said.

IAG also posted an operating profit for the second quarter of 293 million euros ($300 million), compared with an operating loss of 967 million euros in the same period of 2021, the first time it has delivered a profit since 2019.

"This result supports our outlook for a full year operating profit," Chief Executive Luis Gallego said. IAG’s shares rose 2.5% in early trade before drifting back to be flat.

The owner of Iberia, Vueling and Aer Lingus is returning to some form of normality following the most turbulent two years in the history of flying, when COVID-19 left airports deserted, planes parked up and many airlines going bust.

In recent months the industry, particularly in Europe, has struggled to cope with the rapid rebound in demand, with huge queues building at many airports due to a shortage of staff, prompting last-minute cancellations and angry scenes.

However, a move to limit flight numbers by the industry appears to have stabilized the situation. London’s Heathrow and lower cost airlines such as easyJet and Wizz Air have all reported improving operations this week.

IAG said its passenger capacity hit 78% of 2019 levels in the second quarter, and forecast capacity of around 80% in the third quarter, and around 85% in the fourth.

That’s down from previous estimates of 85% and 90% for the third and fourth quarters respectively, due to the ongoing disruption at Heathrow for BA.

Gallego told reporters he hoped Heathrow would have stabilized by the end of the year.

"Our industry continues to face historic challenges due to the unprecedented scaling up in operations, especially in the UK where the operational challenges of Heathrow airport have been acute," Gallego said.

IAG noted that fourth-quarter bookings were seasonally low, but it was seeing no signs of weakness in demand.