US is investigating Delta's flight cancellations and faltering response to global tech outage

U.S. regulators are investigating why Delta Air Lines failed to recover as quickly as other airlines from a global technology breakdown and whether Delta's treatment of passengers stranded by canceled and delayed flights violated federal rules.

Transportation Secretary Pete Buttigieg on Tuesday announced the investigation into Delta's response to the outage, which he said has affected more than half a million of the airline's passengers.

A Delta official said the airline expects to return to normal operations by the end of the week.

Delta and its Delta Connection partners canceled more than 500 flights Tuesday. That was down by more than half from Monday but still accounted for nearly two-thirds of all canceled flights in the United States, according to tracking platform FlightAware.

Many airlines were affected when cybersecurity company CrowdStrike sent a faulty update to more than 8 million Microsoft computers around the world late last week. Most of them reduced cancellations to roughly normal levels by the end of the weekend.

Atlanta-based Delta and its partners have canceled more than 6,500 flights since Friday, far more than any other airline, according to figures from FlightAware and travel-data provider Cirium.

Buttigieg said his department will investigate “how it could be that days after the other airlines are back to normal, Delta is still canceling hundreds of flights.”

At a news conference, Buttigieg said the Transportation Department will also examine Delta's customer service, including “unacceptable” lines for customer service and reports that unaccompanied minors were stranded at airports. He said the department has received more than 3,000 complaints about the airline's breakdown.

Delta said it was cooperating with the investigation.

“We remain entirely focused on restoring our operation after cybersecurity vendor CrowdStrike’s faulty Windows update rendered IT systems across the globe inoperable,” an airline spokesperson said in a statement. “Across our operation, Delta teams are working tirelessly to care for and make it right for customers" affected by the disruptions.

John Laughter, Delta’s chief of operations, said the airline was moving planes, pilots and flight attendants “to where they need to be so we can return to normal operations by the end of the week.”

The collapse at Delta has been stunning for an outfit that was widely viewed as the best big U.S. airline — the most profitable before and after the pandemic, and the best-run. In recent years, Delta has almost always ranked near the top among all U.S. carriers for on-time performance.

Delta appears to rely more than other airlines on systems that run on Microsoft Windows. The airline said upward of half its technology systems are Windows-based, including a key tool used to schedule pilots and flight attendants. That system could not keep up with the high number of changes triggered by the outage.

Delta said late Tuesday that a backlog of “issues” in the crew-scheduling system was reduced by 75% over the last 36 hours, and the airline was also making progress in returning lost bags to their owners.

In addition to probing the cause of Delta's collapse, investigators are likely to focus on whether Delta is complying with federal requirements such as offering prompt refunds to passengers whose flights are canceled or significantly delayed. The refunds are supposed to be in the form the customer used to pay for their ticket — typically a credit card — and not just a voucher.

In a text provided to The Associated Press, a Delta passenger whose flight was canceled Saturday was told, “If you prefer not to rebook your trip, your ticket value will automatically be available as an eCredit that can be used towards a future Delta ticket.”

In Washington, lawmakers are beginning to weigh in. Sen. Maria Cantwell, D-Wash., chair of the Senate committee that oversees airlines, said in a letter to Delta CEO Ed Bastian that she is “concerned” that Delta is not complying with passenger rights contained in a law that Congress passed in May.

“While the technology outage was clearly not caused by Delta or any airline, I am nevertheless concerned that Delta is failing to meet the moment and adequately protect the needs of passengers,” Cantwell wrote.

Delta’s meltdown mirrors that of Southwest Airlines, which canceled nearly 17,000 flights over 15 days in December 2022. A Transportation Department investigation ended with Southwest agreeing to pay a $35 million fine as part of a $140 million settlement.

Southwest blamed its breakdown on a winter storm, but other airlines recovered in a couple days while Southwest did not. Consumer advocates see the same pattern with Delta this month — the airline continues to blame the CrowdStrike outage while rivals such as American recovered quickly. Even United Airlines, the second-worst at cancellations, was back on track Monday.

“It's not about the thing that caused the problem, it's about how you recover from the problem. That's the test of an airline,” said William McGee, a former aircraft dispatcher who is a consumer advocate at the American Economic Liberties Project, a group critical of large corporations.

FILE - A Delta Air Lines plane leaves the gate on July 12, 2021, at Logan International Airport in Boston. U.S. airline regulators have opened an investigation into Delta Air Lines, which is still struggling to restore operations on Tuesday, July 23, 2024, more than four full days after a faulty software update caused technological havoc worldwide and disrupted global air travel. (AP Photo/Michael Dwyer, File)

A Delta Air Lines jet leaves the gate, Friday, July 19, 2024, at Logan International Airport in Boston. (AP Photo/Michael Dwyer)

Travelers stand in line at a Delta Air Lines counter at Reagan National Airport on Friday, July 19, 2024, in Arlington, Va. A global technology outage caused by a faulty software update grounded flights, knocked banks and media outlets offline, and disrupted hospitals, small businesses and other services on Friday, highlighting the fragility of a digitized world dependent on just a handful of providers. (AP Photo/Mark Schiefelbein)

Among the last words heard from the crew of an experimental submersible headed for the wreck of the Titanic were “all good here,” according to a visual re-creation of the journey of the Titan before it imploded, killing all five on board.

The U.S. Coast Guard presented the animation Monday on the first day of what is expected to be a two-week hearing on the causes of the implosion. Crew aboard the Titan were communicating with staff aboard the support ship Polar Prince via text messages, according to the presentation.

The crew lost contact after an exchange of texts about the submersible's depth and weight as it descended. The Polar Prince then sent repeated messages asking if the Titan could still see the ship on its onboard display. One of Titan’s final responses, which became spotty as it descended, was “all good here.”

The Titan imploded on June 18, 2023, killing all five on board and setting off a worldwide debate about the future of private undersea exploration.

In other testimony Monday, Coast Guard officials said the Titan was left exposed to weather and elements while in storage for seven months in 2022 and 2023. The hull was also never reviewed by any third parties as is standard procedure, they said.

The ongoing Marine Board of Investigation is the highest level of marine casualty investigation conducted by the Coast Guard. When the hearing concludes, recommendations will be submitted to the Coast Guard's commandant. The National Transportation Safety Board is also conducting an investigation.

“There are no words to ease the loss endured by the families impacted by this tragic incident,” said Jason Neubauer of the Coast Guard Office of Investigations, who led the hearing. “But we hope that this hearing will help shed light on the cause of the tragedy and prevent anything like this from happening again.”

Among those killed was Stockton Rush, co-founder of OceanGate, the Washington state company that owned the Titan. The company suspended operations after the implosion. The first witness to testify Monday was OceanGate's former engineering director, Tony Nissen. Also scheduled to speak were the company's former finance director, Bonnie Carl; and former contractor Tym Catterson.

Some key OceanGate representatives are not scheduled to testify. They include Rush's widow, Wendy Rush, who was the company's communications director.

The Coast Guard does not comment on the reasons for not calling specific individuals to a particular hearing during ongoing investigations, said Melissa Leake, a spokesperson for the Coast Guard. She added that it's common for a Marine Board of Investigation to “hold multiple hearing sessions or conduct additional witness depositions for complex cases.”

Scheduled to appear later in the hearing are OceanGate co-founder Guillermo Sohnlein; former operations director, David Lochridge; and former scientific director, Steven Ross, according to a list compiled by the Coast Guard. Numerous guard officials, scientists, and government and industry officials are also expected to testify. The U.S. Coast Guard subpoenaed witnesses who were not government employees, Leake said.

OceanGate has no full-time employees at this time but will be represented by an attorney during the hearing, the company said in a statement. The company has been fully cooperating with the Coast Guard and National Transportation Safety Board investigations since they began, the statement said.

The Titan became the subject of scrutiny in the undersea exploration community in part because of its unconventional design and its creator’s decision to forgo standard independent checks. The implosion killed Rush and veteran Titanic explorer Paul-Henri Nargeolet; two members of a prominent Pakistani family, Shahzada Dawood and his 19-year-old son Suleman Dawood; and British adventurer Hamish Harding.

The Titan lost contact with its support vessel about two hours after it made its final dive later. When it was reported overdue, rescuers rushed ships, planes and other equipment to an area about 435 miles (700 kilometers) south of St. John’s, Newfoundland.

The search for the submersible attracted worldwide attention, as it became increasingly unlikely that anyone could have survived the implosion. Wreckage of the Titan was subsequently found on the ocean floor about 330 yards (300 meters) off the bow of the Titanic, Coast Guard officials said.

The time frame for the investigation was initially a year, but the inquiry has taken longer. The Coast Guard said in July that the hearing would delve into “all aspects of the loss of the Titan,” including both mechanical considerations as well as compliance with regulations and crewmember qualifications.

This story has been edited to clarify that “all good here” was one of the last things heard from the submersible, not necessarily the very last thing heard.

FILE - This undated image provided by OceanGate Expeditions in June 2021 shows the company's Titan submersible. (OceanGate Expeditions via AP, File)