Cathay Pacific Airways has drastically scaled back its expansion plans this year, including postponing new international routes and delaying a planned increase in flight frequency, and pinned the blame on its cockpit crew's year-long work-to-rule action.

Among the stymied plans were the introduction of daily flights to Manchester and Boston, which were postponed to next year, and the launch of flights to London's Gatwick airport, pushed back to September, the Post learned.

In a letter to the company's pilots sent in December last year, general manager of aircrew Dominic Perret called the labour stalemate a "lose-lose" situation and "frustrating for all of us".

"Our growth plans for 2016 have recently been scaled back considerably, and there are a few reasons why we have made the difficult decision to do this," he stated in the letter seen by the Post. "There are certainly operational reasons - we have built more slack into the system to help improve our poor on-time performance and to make the roster more stable."

"Other reasons for our slower growth are clearly industrial - namely the campaign led by the HKAOA here in Hong Kong of contract compliance and the training captain ban."

The Hong Kong Aircrew Officers Association, representing 2,100 of Cathay Pacific's 2,900 pilots, launched a work-to-rule action in December 2014 over a pay rise dispute. Although the issue was resolved, pilots vowed to continue the action because of other disputes, such as roster patterns.

The association also called on training captains to suspend training other pilots, thus affecting the airline's manpower plans.

Under the work-to-rule action, pilots did the bare minimum as laid out in their contracts, including not working on their days off, as they typically did.

In his letter, Perret warned that business would suffer and Cathay Pacific's competitiveness was being "weakened".

But one airline pilot countered: "We're happy to do the work. Just don't kill us and, potentially, your customers because you won't spend the time or money on constructing safe rosters. God forbid that there should be an accident or incident where fatigue can be seen as a casual factor. Cathay management will be culpable if this happens."

The pilot added: "We have rosters being flown where individuals are losing up to 10 nights' sleep every month. They are unable to sleep when their body wants them to 10 times a month. Is this healthy or sustainable?"

A company spokesman said the airline remained willing and ready to discuss all matters of mutual interest with the pilots union.

Cathay Pacific would continue to grow, he said, with four new weekly services to Madrid, Spain, in June, as well as the Gatwick initiative.

"We are scheduled to take delivery of 12 A350 aircraft this year," the spokesman said. "We regularly review our capacity plans, in accordance with market demand and resources, and will continue to do so for 2016 and beyond."