American Airlines Group Inc. affiliate PSA Airlines expects more flight cancellations on Tuesday after scrubbing about 400 flights over the weekend as the regional carrier moves into its sixth day of problems with its crew-scheduling system.

The technology issue arose on June 14 and has affected nearly 1,100 PSA flights to date, mainly in Charlotte, North Carolina, American spokeswoman Katie Cody said Monday. A few PSA flights at Philadelphia and Washington Reagan National airports have also been affected. PSA, a wholly owned subsidiary of American, is also likely to operate less than its full schedule on Wednesday, she said.

“It started on Thursday and they thought they had it fixed and it’s kind of slowly still been remaining an issue,” Cody said. Charlotte is American’s second-largest hub.

PSA canceled about 675 flights Thursday-Friday, and about 50 on Saturday. But the troubles cropped back up on Sunday, forcing hundreds more schedule disruptions for passengers that continued through Monday. American has sent technology staff from its Fort Worth, Texas, headquarters to PSA, based in Dayton, Ohio, to try to help. The problems involve hardware for scheduling and tracking PSA pilots and flight attendants, Cody said.

American has begun culling some PSA flights early to try to mitigate effects on customers. “We honestly don’t know when it’s going to be fixed,” she said. “We’re working on it 24/7.”

American shares fell less than 1 percent Monday to $42.44.