We know why the list has gotten much longer for 'rowdy passengers' this past year - it's the mask mandate and in a number of cases, some people have not been allowed to fly on one airline or another EVER AGAIN because their child kept taking a mask off. This is absurd and abusive behavior on the part of corporations.
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https://www.tripsavvy.com/delta-air-lines-no-fly-list-5205829

Delta Is Pushing for Banned Passenger Lists to Be Shared Between Airlines

"Something’s been in the air ever since COVID-19 came on the scene: rowdy airline passengers. Ever since air travel started picking back up last year, so have the numbers of unruly passengers. Between Jan. 1, 2021, to Oct. 12, 2021, the Federal Aviation Administration received 4,724 reported cases of unruly passengers. It’s the most ever, by a long shot, since 1995 when the agency began recording reports.

Several in-air offenses, like refusing to comply with the mask mandate or assaulting a flight crew member, are dealt with via hefty fines. However, airlines reserve the right to punish unruly passengers by placing them on their own internal “no-fly” list, which bans the disruptive passenger from flying that airline for life.

The apparent loophole is that, as Kristin Manion Taylor, Delta’s senior vice president of in-flight service, shared in a memo to flight attendants last month, “a list of banned customers doesn’t work as well if that customer can fly with another airline.”

For this reason, Delta has offered to share their banned passenger lists with other airlines—and urge all airlines to do the same to keep disruptors out of the air for good."