FILE PHOTO - A Southwest Airlines jet taxis on the runway at Washington National Airport in Washington, U.S., August 9, 2017. REUTERS/Joshua Roberts

(Reuters) - The U.S. Federal Aviation Administration is investigating Southwest Airlines Co for widespread failure to accurately track the combined weight of checked bags loaded onto its jets, the Wall Street Journal reported on Monday.

The U.S. aviation safety agency’s year-long civil probe found systemic and significant mistakes with employee calculations and luggage-loading practices, resulting in potential discrepancies when pilots compute takeoff weights, the Journal reported, citing government officials and internal agency documents

The FAA has not decided whether to impose fines or any other punishment, the report cited people familiar with the investigation as saying.

The inaccuracies ranged from a few dozen pounds to more than 1,000 pounds (450 kg) in excess of what the paperwork indicated, sparking disputes between the company and some agency inspectors about potential safety consequences, the report said.

A company spokeswoman said there was an open Letter of Investigation (LOI), which is a common mechanism for the FAA to document and share safety interests or concerns with an airline.

The airline has not been issued fines and faces no enforcement action regarding its weight and balance program, Southwest spokeswoman Brandy King said.

“In this case, the LOI addresses an issue that Southwest voluntarily reported to the FAA last year and since that time, Southwest has implemented controls to address weight and balance program concerns, and shared those measures with the FAA,” King said.

The FAA said in a statement it initiated a probe against Southwest in 2018 regarding weight and balance performance data.

“Since that time, the FAA has directed the development of a comprehensive solution to the methods and processes used by Southwest Airlines to determine this performance data,” it said in the statement. “The FAA will not close its investigation until it is satisfied that Southwest’s corrective actions are consistent and sustained.”