Ontario International Airport recorded its fourth consecutive month of passenger growth in March, welcoming 574,819 travelers — a 2.7% year-over-year gain — while commercial air freight tonnage climbed 15.3%, airport officials announced. The headline numbers were driven almost entirely by international traffic, which surged 55.2% to 60,042 passengers in March against the same month last year. Domestic volumes edged down 1.2% to 514,777. Through the first quarter, ONT served 1,546,339 total passengers, up 4.