“Cathay Pacific experienced higher than anticipated pilot absence caused by seasonal illness on certain days in December. Our operations remain normal overall, with a marked increase in the number of flights operated over the holiday peak season,” it said.

“We have chosen to proactively cancel a small number of flights in order to ensure the successful delivery of our overall services. The total number of cancellations since mid-December is less than 1 per cent of all passenger flights operated.”

According to the websites of the carrier and Hong Kong International Airport, at least 28 flights scheduled between Friday and the coming Sunday had been cancelled.

At least sixteen were cancelled from Sunday to Thursday, including long-haul flights to London and Amsterdam.

The airline has 2,532 pilots as of this month compared with 3,885 in the fourth quarter of 2019, just before the pandemic, according to the Hong Kong Aircrew Officers Association.

“This is what happens when you don’t have enough pilots. There will always be some illness among crew, but this doesn’t mean flights have to be cancelled,” chairman of the union Paul Weatherilt said.

“A year into the recovery and the airline’s passenger operation still has only 52 per cent of the captains and first officers that it had pre-pandemic.”

He added that while many other airlines had fully recovered, Cathay Pacific had “stalled”, warning that it would take years to complete training which could hamper the city’s return to global aviation hub status.

A source familiar with cockpit crew operations said a staff shortage had led to many flight delays, as the airline had to locate pilots scheduled for later flights to cover for the earlier ones.

Even pilots in managerial positions who typically would not fly were called to help with the dire situation, the insider said, adding there were instances where cockpit crew members were asked to return to work right after a 12-hour rest period, the minimum legal requirement.

The source said Cathay pilots generally had less rest now and increased uncertainty regarding when they could expect to have rest.

As worldwide travel was brought to a standstill amid the Covid-19 pandemic and the city imposed stringent flight restrictions, the carrier experienced a staggering 99 per cent drop in daily passenger numbers.

In October 2020, Cathay announced Hong Kong’s biggest mass lay-offs in three decades, cutting 5,300 jobs locally and terminating its regional airline in a desperate restructuring bid to survive the pandemic.

About 4,000 cabin crew, 600 pilots, and 700 ground staff and office workers were made redundant in the HK$2.2 billion restructuring. The remaining cabin crew and pilots were given cost-saving contracts.

The union earlier this month said training, recruiting and retaining pilots had been challenging for the airline, which had only added 107 pilots to its workforce so far this year. It warned that it might take up to four years to reach the number of pilots it had before the pandemic.

Cathay is on a massive recruitment drive, with plans to hire another 5,000 workers in 2024 on top of the 4,000 this year.

The airline said in a traffic report last month that its priority next year was rebuilding its flights, but constraints included recruiting and training staff and supply chain challenges.

Cathay and its budget carrier HK Express aim to fully restore pre-pandemic passenger capacity by the end of 2024.

The carrier is expected to announce its first annual profit since 2019 after recording a better performance in the second half of the year compared with the first because of higher ticket prices and strong travel demand.

Additional reporting by Jeffie Lam