Air travel is full of opportunities for coronavirus transmission. Touchless check-in, plexiglass shields, temperature checks, back-to-front boarding and planes with empty middle seats are all now part of the flying experience, and the future may bring even more changes. Illustration: Alex Kuzoian Delta Air Lines Inc. trimmed plans for more summer flights amid rising Covid-19 cases nationwide after a $5.7 billion loss for the latest quarter underscored the depth of the crisis facing the aviation industry. Chief Executive Ed Bastian said that the recovery from April’s near-collapse in domestic flying had stalled. Delta will halve the number of extra flights it adds in August to 500, and capacity in the September quarter is expected to be at best 25% of the level a year ago. …