Delta became the first airline to release financial results showing the early effects of the coronavirus pandemic on travel businesses, but data from several sources shows how much worse things will get for airlines in the months ahead. Delta’s $534 million loss in the first three months of the year — its first quarterly setback in more than five years — mostly covered a period before the pandemic caused air travel within the U.S. to plummet. As passenger numbers plunged, airlines cut flights. Data firm Cirium says that worldwide airlines have grounded nearly 17,000 planes, or 64% of the global fleet. That’s not enough. Figures from Airlines for America, a trade group, show that on average there are now only about 12 passengers per domestic flight. Normally it’s about 100. The percentage of seats filled by paying customers has dropped into the teens. As other airlines hold conference calls over the next week, investors will listen for news about plans to boost liquidity enough to ride out the pandemic. Government aid — more than $19 billion so far to Delta, American, United and Southwest — will help. Either way, the airlines will be smaller after COVID-19.