Federal transportation officials have started a formal investigation into Delta Air Lines. Many airlines were hit by the CrowdStrike software update which went terribly wrong Friday. Delta, in particular, has stranded a lot of passengers in the last few days, though mercifully its cancellations are finally way down this morning.

In Atlanta — Delta’s primary hub — it’s been chaos all week, and some passengers are fed up.

The Atlanta Hartsfield-Jackson International Airport was so jammed this week that hundreds of suitcases filled the spaces even in between the carousels of Delta’s baggage claim area. 

One traveler, Cassandra Andrews, was relieved when she saw her bag around the corner. She just got  back from an exhausting trip to New York. “It was just a madhouse,” she said.

Her Friday Delta flight out was canceled because of the outage. “I mean, we, we started breaking down crying, because I didn’t think I would get out for my mother’s funeral.”

Andrews ended up staying at the airport overnight. The lines at Delta’s desks took forever, she said.

“They kept canceling, and I had to go back at two o’clock in the morning and get in the line for three hours.”

In a statement, Delta said that it is cooperating with the Department of Transportation’s investigation.

John Guzowski and nine family members got stuck in Newark, New Jersey, trying to get home from a cruise. 

“We rebooked the canceled Friday flight to Sunday. Saturday night, they canceled us again,” he said.

They didn’t end up flying out until Tuesday, and Guzowski had to get last-minute hotel rooms for all 10 of them. 

“I’m about $10,000 out of pocket right now for just lodging, food and transportation,” he said. He’s saving his receipts. 

Airlines are required to reimburse necessary expenses in the case of a cancellation or significant delay under their control. Delta says it is offering travel vouchers, hotel rooms and transportation where available. But some passengers say they have not received any assistance or a proper refund.

It will take time to evaluate the full impact of the service outage, said Ramnath Chellappa, a professor at Emory’s Goizueta Business School and studies aviation. But he expects it to cost Delta a lot. 

“$200 million — and we haven’t even gotten to the reputational impact, etc., etc.”

Chellappa said that this is unprecedented — he estimates the last time there were so many flight cancellations was because of 9/11.