Kenya Airways plans to shed staff through voluntary retirement, redundancies and outsourcing of non-core roles in order to contain soaring costs and protect its bottom line, it said on Friday, but unions said they would fight the job cuts.The airline, which is 26.73-percent-owned by Air France KLM, first indicated it would look to slash costs in June, after its full-year pretax profit slid 57 percent due to higher fuel costs and a rising wage bill.Its wage bill had more than doubled over the previous six years to 13.4 billion shillings while the total number of staff had risen by just over 16 percent to 4,834.The carrier, one of the largest in sub-Saharan Africa alongside Ethiopian Airlines and South African Airways, did not indicate the level of savings it was targeting or how many jobs would be lost in the exercise.The Aviation and Allied Workers Union (AAWU), which includes 3,800 members from the carrier, promised to use all means at its disposal, including going to court, to stop the job cuts."We think what they (Kenya Airways’ management) are doing is just a sideshow because they are sacrificing workers for their failures,” Perpetua Mpojiwa, head of AAWU, told Reuters.She questioned why the exercise was announced soon after the airline unveiled an ambitious five-year expansion plan, which would inevitably require hiring staff, rather than job cuts.Kenya Airways said in March it would spend $3.6 billion, mainly to buy new planes and start new routes between Africa and Asia.