FILE PHOTO: The Boeing logo is seen at their headquarters in Chicago, in this April 24, 2013 file photo. REUTERS/Jim Young/File Photo/File Photo

SEATTLE (Reuters) - Boeing Co said on Thursday that a new software fix for its anti-stall system, at the center of investigations into two deadly plane crashes, will give pilots the authority to always override the system if activated by faulty sensor data.

The world’s largest planemaker, facing its worst crisis in years and the worldwide grounding of its top-selling jetliner, said its software upgrade and associated pilot training will add additional layers of protection to prevent erroneous data from triggering its so-called MCAS system.

The system activated in the Ethiopian Airlines crash last month and also during a separate Lion Air crash in Indonesia in October, Boeing said in a statement following the release of preliminary findings from Ethiopia.

“Understanding the circumstances that contributed to the Ethiopian accident is critical to ensuring safe flight,” Boeing Commercial Airplanes Chief Executive Kevin McAllister said in a statement.

He said Boeing would carefully review the preliminary report and take “any and all” additional steps necessary to enhance the safety of Boeing aircraft.