British Airways, part of International Airline Group, said 1,200 jobs were under threat as a result of plans to integrate UK regional airline bmi into its Heathrow operations.
The airline said on Thursday it had begun a consultation with unions over the proposed job cuts.
Last month BA was given regulatory approval from the European Commission to buy bmi from German carrier Lufthansa. The deal is expected to complete later this month.
BA said the integration plan for bmi, which is losing over 3 million pounds ($4.8 million) a week, would retain about 1,500 jobs, including around 1,100 cabin crew, pilots and engineers based at Heathrow.
The number of Britons claiming unemployment benefit currently stands at the highest level since November 2009.
Earlier on Thursday, retailer Mothercare said it would close 111 stores in Britain, putting 750 jobs at risk. Meanwhile, a decision by Sony Corp to cut 10,000 jobs worldwide raised questions over the future of its 450 workers in Wales.
The Unite union said on Thursday it would fight to save as many jobs at BMI as possible.
BMI's future has been secured but we are very saddened at the scale of the job losses being proposed, the union said, adding that it would look to ensure that, where vacancies exist, BMI workers can be placed within roles at BA.
($1 = 0.6288 British pounds)
(Reporting by James Davey and Matt Scuffham; Editing by Kate Holton and Erica Billingham)