At a time IndiGo and SpiceJet are locked in a spat over the methodology adopted by the Directorate General of Civil Aviation (DGCA) for computing on-time performance (OTP) of airlines, data for December once again show SpiceJet topping the chart on this parameter, registering a 70% OTP in the top four airports — Mumbai , Delhi, Bengaluru and Hyderabad, reports Malyaban Ghosh in New Delhi. It was closely followed by Jet Airways (64.3%), Vistara (64.2%) and GoAir (63.6%). According to the data, IndiGo, the largest airline by market share, and Air India had the lowest OTP at 61.6% and 59%, respectively, during the month.