Early examples of different solutions to alleviate rotating stall in the front stages include the Rolls-Royce Avon with variable inlet guide vanes and interstage bleed, the General Electric J79 with variable inlet guide vanes and variable stators, the Bristol Olympus with split compressor and the Pratt & Whitney J57 with split compressor and intercompressor bleed. Compressor bleed up to this point had been only necessary for starting and accelerating beyond low corrected speeds where its loss to thrust production, from dumping overboard, was not important.