DALLAS (AP) — Federal officials say that Southwest Airlines and the union representing its pilots have resisted cooperating with investigations into accidents and other incidents and pushed to close the matters quickly.

In one instance disclosed Wednesday, the Federal Aviation Administration cut short an investigation of a 2019 incident in Connecticut even though the agency determined that there was pilot error. Both wings of the Southwest jet were damaged as pilots battling wind tried to land at Bradley International Airport, outside of Hartford.

The FAA said Southwest and union officials resisted interviews with agency representatives in that and other cases. Sometimes the delaying tactics worked. An investigation into why pilots placed duct tape over sensors outside a plane before a flight fizzled when the FAA employee took another job.

Southwest said the allegations are old, and it has cooperated fully with government inquiries.

“As part of our emphasis on safety, we have maintained a transparent and professional relationship with the FAA, including multiple FAA-approved safety programs designed to help us manage and mitigate operational risks and execute safe operating practices,” the company said in a statement.

The union representing Southwest pilots did not respond immediately to requests for comment.

The FAA investigation was disclosed Wednesday by the U.S. Office of Special Counsel, which represents federal whistleblowers. It reported another accident — a plane that went off the runway in Burbank, California — in which an FAA review was “fast-tracked” under pressure from Southwest. In a separate review of that incident, the National Transportation Review Board found that the co-pilot’s conduct was “highly unprofessional.”

The FAA said it agreed with some of the allegations raised by three whistleblowers and took corrective steps including more training and development of audits to ensure compliance with aviation-safety guidelines.

The special counsel’s office investigated eight allegations raised by four whistleblowers. The office forwarded its findings to the White House and Congress.

In a response to the special counsel’s office, the FAA said it found “mismanagement and lack of oversight” by the office monitoring Southwest that has persisted despite management and staff changes over the years. The FAA said new executives will provide “a fresh opportunity to evaluate” the oversight of Southwest.

Some of the whistleblower accusations have been leveled before, including Southwest’s use of planes bought overseas without verifying their maintenance and inspection records. In more than half of those cases, the airline found that the planes had undergone repair work that wasn’t documented or couldn’t be verified.

The FAA said some of the whistleblower allegations couldn’t be proven, including a claim that Southwest routinely assigns too much work for mechanics to handle.

A separate allegation that the FAA improperly certified Southwest for long overwater flights — approval the airline needed to sell flights to Hawaii — was examined by the Transportation Department’s inspector general, who could not verify the claim.

An FAA spokeswoman said the agency takes the special counsel’s concerns seriously and has adopt its recommendations.

Dallas-based Southwest has faced questions about safety over the years and has paid millions to settle safety violations, however, it has a good record over its five-decade history.

No passenger had died in an accident involving a Southwest plane until 2018, when a woman was killed after an engine broke apart over Pennsylvania and debris shattered the window next to her seat. In 2005, a 6-year-old boy riding in a car was killed when a Southwest jet landing during a snowstorm in Chicago skidded off the runway, crashed through a fence and hit the car.

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