The US Federal Aviation Administration (FAA) has admitted in its response to an audit by the Office of Inspector General (OIG) and the US Department of Transportation (DOT) that it did not carry out safety oversight of Southwest Airlines (WN, Dallas Love Field) "in accordance with existing guidelines".

"We agree that the Southwest Airlines (SWA) FAA Certificate Management Office (CMO) did not perform in accordance with existing guidance by allowing 88 aircraft (the 'Skyline' aircraft) to enter service through SWA's conformity process, which lacked a comprehensive conformity inspection for used aircraft. Regarding performance weight and balance, we agree the SWA CMO, at times, did not perform in accordance with existing guidance," the FAA wrote in its memorandum on January 30, 2020.

The agency added that once its leadership became aware of the issues, it immediately took steps to address them. In particular, it appointed a new CMO leadership team in June 2019, increased direct involvement in aircraft inspections and reassessed older inspections, and ramped up efforts to ensure compliance with weight and balance procedures.

In its report published on February 11, the Office of the Inspector General said that it had "identified a number of concerns and gaps regarding the FAA's safety oversight of Southwest Airlines."

In particular, the concerns related to two matters. The first of them regarded the LCC operating aircraft with "unresolved security concerns" stemming from two areas: defective weight and balance procedures, and the operation of second-hand B737NGs whose airworthiness checks had been conducted improperly. The second issue related to the fact that "FAA inspectors do not evaluate air carrier risk assessments or safety culture as part of their oversight of Southwest Airlines' SMS" given inspectors have not been provided with "guidance on how to review risk assessments or evaluate safety culture".

The OIG said that the responses it received from the FAA before the publication of the report allowed it to "consider all recommendations resolved but open pending completion of the planned actions."

Southwest said in a statement to Reuters that it had yet to complete Repair Assessment Program checks for eight out the 88 second-hand B737NGs. The LCC added it adamantly disagreed with "unsubstantiated references" to its allegedly lax safety culture.