The state-run oil companies on Thursday cut rates by 1.6 per cent, a move that will ease burden on cash-strapped airlines. An official of the nation's largest oil firm, Indian Oil Corporation said, Aviation Turbine Fuel (ATF) prices in Delhi was reduced by 636 rupees a kilolitre to 38,697 rupees per kilolitre, effective from Thursday midnight. In Mumbai, ATF will now cost 39,911 rupees, in Kolkata, it will be 46,909 rupees and that in Chennai 42,683 rupees per kilolitre.The three oil firms revise jet fuel prices on the first and the 16th day of every month based on the average global oil price in the previous fortnight.Jet fuel constitutes roughly 40 per cent of the operating cost of an airline and the reduction in fuel rates would help ease the burden of Indian carriers, most of whom are loss making.