Delta Air Lines lost $1.2 billion in the first quarter, more than expected, but executives said Thursday that the airline could be profitable by late summer if the budding recovery in air travel continues. CEO Ed Bastian said Thursday that ticket sales have been stronger in the last two weeks than at any time since the pandemic hit the United States last year. So far most of the people boarding planes are vacationers booking trips to mountains, beaches, and resorts. The increase in passengers, combined with lower costs for labor and fuel, helped Delta generate $4 million in cash per day in March after burning cash for the past year. “It’s clear that our business is turning the corner and we’re moving into an active recovery phase,” Bastian said in an interview. “We see the business continuing to improve as consumer confidence grows.” However, Delta shares fell 2 percent in …