Budget carrier IndiGo , which controls more than 40 per cent of the domestic market in India, is struggling with shortage of pilots. Though the problem came to light in the past week when the airline cancelled hundreds of flights, in the last one and a half months alone, as many as 1,200 of its scheduled flights have been cancelled due to crew shortages and pilots reporting sick.IndiGo said last week that scheduled cancellations of 30 flights every day would continue till March 31. Its crew addition has lagged its aggressive capacity addition. It plans to hire more than 100 expatriate pilots this year to add to its roster of flight captains. According to an ET Prime report , one reason behind IndiGo's pilot trouble is inefficient rostering.It all started around two years ago when the airline brought in expat managers to handle its expanded fleet. It now has a fleet of 209 aircraft, more than double the 100 it flew in 2015. But planes need pilots to fly. IndiGo’s pilots, according to ET Prime , were flying less than the total number of hours anticipated. Indian regulations allow pilots to fly 1,000 hours a year. The expat team decided that pilot productivity needs to go up, since they are an expensive resource. To achieve this target, the new team did many experiments. Millions of dollars were spent on software to optimise crew rostering. It was intended to ensure that the expanded fleet could be run with the same number of pilots.The new rostering kept pilots away from their home base for long periods affecting their personal lives. While in the earlier flying pattern most pilots would do flight rotation on the same plane, now they had to switch planes.IndiGo’s plans to have extremely high pilot utilisation was also impractical, given that it has flights of only one and a half hour on average. While utilisation of 900-1,000 hours is quite common on international flights, it’s difficult to achieve in short-haul flights with multiple landings and take-offs.Disgruntled pilots even thought of forming a union late last year and had created a dedicated WhatsApp group towards that objective, forcing the management to react. Ashim Mittra, senior vice-president of flight operations at IndiGo, assured pilots around December in a bid to diffuse tensions. He also formed a committee to look into the rostering grievances. To be sure, IndiGo had kept its pilots happy in 2017-18 through large-scale promotions — some 700 pilots were promoted from first officers to senior first officers and captains to trainers — but is now running out of ideas. Since then attrition has shot up — cabin-crew attrition, which was controlled at 14%, has shot up to around 20%, while pilot attrition of 4% is now at around 10%.IndiGo has never had a union so far because in the past it had weekly dialogues with pilots to iron out issues. That process largely ended with the new expat team taking over.