PARIS (Reuters) - Air cargo in March fell by 15% from a year earlier, airlines body IATA said on Tuesday, as the coronavirus pandemic triggered travel restrictions. Air cargo, measured in tonne-kilometres, could fall by between 14% and 31% this year as a recession takes hold, IATA said. Airlines have been converting passenger aircraft to carry freight in recent weeks, IATA noted.Cargo capacity is down since passenger planes carry cargo in their bellies.