Cathay Pacific yesterday wrote to pilots warning that the prospect of negotiations with their current union leadership was 'unthinkable'. The letter comes less than six months before the expiry of the pilots' current contracts, as a protracted industrial dispute drags on. It accused the Aircrew Officers' Association (AOA) leadership of taking a new approach this year designed to position Cathay Pacific as an 'unsafe airline'. Damage to the airline's revenue had run into hundreds of millions of dollars, according to the letter. The union leadership had 'taken a step too far' and lost 'any last shred of trust' from management in shifting the focus to safety, the letter said. However, it implied Cathay might negotiate with the pilots over pay and rostering under a different regime by mentioning the prospect of completing a rostering agreement. 'It is unthinkable that there could be any meaningful dialogue with an AOA leadership hell-bent on trying to damage the revenue streams and the safety reputation of the airline,' the letter said. Pilots last week reintroduced contract compliance, a measure under which they refuse to work on their days off, which is unlikely to cause delays. Contract compliance and a work-to-rule campaign were suspended last year in an effort to restart talks with management but - after a single meeting - Cathay refused to negotiate further. When pilots voted for the reintroduction of contract compliance last month, the union said it was because 'we cannot work with a system that might compromise the safety of our passengers'. Yesterday's letter, from Cathay's director of flight operations Ken Barley, said the impact of the September 11 terror attacks made the new phase of industrial action particularly disappointing. 'I do not believe that any of you genuinely believe that industrial action is now necessary to protect the safety of the travelling public,' he said. Cathay's director of corporate development Tony Tyler said the airline had stopped short of saying it would never negotiate with the current leadership - but said the union would have to demonstrate it was not interested in damaging the company before any talks could take place. 'All they really want now is a way of saving face with some form of company climbdown. We're not going to climb down to give face to a group of people who do nothing but damage our company,' he said. John Findlay, general secretary of the AOA, said the management's letter was 'threatening' and 'the most cynical spin of all'. He said: 'At no time have or would Cathay Pacific's 1,500 pilots ever claim that the airline is unsafe.'