July 24 (Reuters) - Delta Air Lines ( DAL ), which has

axed more than 6,000 flights since a widespread IT system

failure on Friday, said it would resume normal operations

Thursday.

The Atlanta-based carrier as of 8 a.m. ET (1200 GMT) had

canceled just 47 of Wednesday's flights - only 1% of its daily

total - after scrapping 511 on Tuesday and 1,160 on Monday.

CEO Ed Bastian said in a statement that Delta expected

"minimal" cancellations Wednesday and a return to normal

operations Thursday, adding: "Our initial efforts to stabilize

the operations were difficult and frustratingly slow and

complex."

A software update by global cybersecurity firm CrowdStrike ( CRWD )

triggered system problems for Microsoft ( MSFT )

customers, including many airlines, on Friday. But disruptions

subsided the next day at other major U.S. carriers while

persisting at Delta.

The U.S. Transportation Department opened an investigation

Tuesday into the Delta disruptions, which affected more than

500,000 passengers and stranded people across the United States.

Transportation Secretary Pete Buttigieg said the

investigation is focused on how the breakdown happened, why it

had taken Delta so much longer than others to recover, and the

level of Delta's customer service resources.

"We require a basic level of customer service," he added.

Many customers complained of waiting hours for assistance as

the airline's helplines were overwhelmed. Some were forced to

rent cars, driving hundreds of miles to get to destinations,

while others said they would have to wait days for new flights.

Representative Rick Larsen, the top Democrat on the House

Transportation Committee, said he will introduce legislation to

boost the operational resilience of airlines in the near future.

"The slow response by some airlines to this meltdown has been

unacceptable," Larsen said.

Senate Commerce Committee chair Maria Cantwell said she is

concerned Delta is not complying with passenger rights

obligations under a new law.

In December, Southwest Airlines ( LUV ) agreed to a record

$140 million civil penalty over a 2022 holiday meltdown that led

to 16,900 flight cancellations and stranded 2 million

passengers, resolving a U.S. Department of Transportation

investigation.