American Airlines grounds crew members sit and wait for luggage cart to arrive June 23, 2018, at Charlotte Douglas International Airport in Charlotte, N.C.
Kiichiro Sato, AP

American Airlines acknowledged Wednesday that a computer glitch in June cancelled about 3,000 flights, many at Charlotte Douglas International Airport, and cost the carrier $35 million.

American said the information-technology problem at PSA Airlines, a wholly owned regional carrier, disrupted flights for a week starting June 14, according to a filing at the Securities and Exchange Commission.

"We understand that these cancellations have been frustrating for our customers, and we are doing everything in our power to get things back to normal as quickly as possible," American Airlines said in a statement at the time. "We are rebooking passengers and American's customer relations department will be reaching out to all affected customers."

American will report its second-quarter earnings July 26.

The IT problems cost American an estimated $35 million in pre-tax income, according to the filing. Overall, the airline reported $215 million in special items during the second quarter that covered expenses from investing in China Southern Airlines and bankruptcy obligations, and included a $26 million write-off for route authority to Brazil, which now has an Open Skies agreement with the U.S.