BOSTON―Delta Air Lines said on Sunday that its ticket sales had stabilized and started to improve, putting it on course to deliver third-quarter revenue within its original forecast for a 30 percent-35 percent drop versus corresponding 2019 levels. This is an improvement from its projection last month when it adjusted the forecast to the lower end of that range after a resurgence in COVID-19 cases. The airline is due to report results for the quarter through September on Oct. 13. “For Delta, they bottomed out in the later part of August and the first part of September,” Chief Executive ED Bastian told reporters on the sidelines of a meeting of airlines group IATA. “Business traffic is growing back in the U.S.” Domestic travel bookings are expected to surpass 2019 levels next year, Bastian added. Later, the airline said it would boost its capacity by more than 20 percent next summer …