(CNN) -- Northwest Airlines violated more than 1,000 Federal Aviation Administration safety directives, the U.S. Office of Special Counsel has found, substantiating complaints of an FAA whistleblower.
Northwest, now merged with Delta Airlines, engaged in "systemic non-compliance with FAA Airworthiness Directives," the investigation concluded, referring to government rules designed to remedy an unsafe or potentially unsafe condition.
"Despite Northwest's history of Airworthiness Directive non-compliance," the Office of Special Counsel said, "FAA inspectors continued to work collaboratively with Northwest to resolve deficiencies, and closing enforcement cases primarily by issuing letters of correction rather than seeking civil penalties."
Whistleblower Mark Lund of the FAA's former Northwest inspection office in Bloomington, Minnesota, alleged that the carrier did not have adequate policies and procedures in place in 2008 to ensure compliance with safety regulations.
"The investigation substantiated Mr. Lund's allegations," wrote Associate Special Counsel William Reukauf in a letter to President Barack Obama.
In response to the findings, FAA Administrator Randy Babbitt has established a review team to oversee the carrier's compliance. The FAA also proposed disciplinary action against two Northwest managers.
The FAA released a statement Thursday saying that the agency "has taken corrective action on the issues identified in the whistleblower complaint and is continuing to monitor compliance."