GMB union reacted strongly on Friday to the British Airways' (BA) takeover of bmi which would result in close to 1,200 job losses.
BA is acquiring the unprofitable bmi from the Luftansa for £172 million.
"bmi is heavily loss making and is not a viable business as it stands today. Our proposals would secure around 1,500 jobs that would otherwise have been lost," said the BA's Chief Executive Keith Williams in a statement.
"As we look to restructure the business and restore profitability, job losses are deeply regrettable but inevitable. We will work with the unions to explore as many options as possible and are already working with industry partners," Williams added.
Most of the redundancies would be in bmi's head office at Castle Donington, Leicestershire and at other regional airports.
Meanwhile the union said it is a black day for its members and will organise a fight to mitigate the job losses.
"The options are redeployment or working with local companies to see if we can move our skilled workers to other environments. We will try and get the best out of it, as it is a very black day," the BBC has quoted the union's regional organisor Colin Wyatt as saying.
"Bmi's future has been secured but we are very saddened at the scale of the job losses being proposed. Unite will be fighting to maintain as many jobs as possible and ensure that, where vacancies exist, people can be placed into suitable roles within BA," the Press Association quoted Unite national officer Oliver Richardson as reacting to the development.
BA's owner International Airlines Group (IAG) was given the nod to acquire bmi by the European Commission at the end of March.
BA has already begun discussions with trade unions on plans to merge bmi mainline into its operations at Heathrow.
The takeover will allow the airlines with an additional 56 average daily pairs at Heathrow, out of which 14 will be available for other carriers.
Discussions are also on with prospective buyers for bmibaby and bmi Regional.