Airline and airport executives spent the past two years trying to convince everyone it’s safe to fly during a pandemic, touting reduced touch points and hospital-grade filters. Little did they know how overwhelmed they’d be once travel came roaring back.

From Sydney, where passengers are waiting for hours to check in, to chaotic scenes in India and Europe, where Deutsche Lufthansa AG is canceling hundreds of flights, the aviation industry doesn’t have nearly enough people to run operations smoothly, even as post-summer demand for travel is still unclear.

As countries reopen borders and COVID-19 curbs fall away, travel has sprung back with such voracity that it’s resulted in an unprecedented labor crunch, made worse by the pandemic-induced layoffs of hundreds of thousands of workers, from pilots to cabin crew and ground-handling staff. Many are in no mood to come back but even if they were, scaling up at such pace is a risk for airlines and airports, with spiraling inflation and economic pressures putting a question mark over how sustainable the current demand really is.