Boeing hasn't received the okay for the software fix for its grounded 737 MAX, but that didn't stop CEO Dennis Muilenberg from trying re-assure the world on Thursday that the problem has been corrected.

SOUNDBITE (ENGLISH): DENNIS MUILENBERG, BOEING CEO, SAYING: "The update will make the 737 MAX even safer by preventing erroneous angle of attack sensor readings from triggering the Maneuvering Characteristics Augmentation System or MCAS - something that initial investigation reports indicate occurred in both MAX accidents, as one link in a longer chain of events.

We know we can break this chain link.

It is our responsibility to eliminate this risk." The crash of an Ethiopian Airlines flight in March and a Lion Air flight in October involving 737 MAX jets killed 346 people combined.

That's resulted in more than 300 of its planes grounded worldwide.

Here in the U.S., Southwest, American and United Airlines have canceled flights at least through May, forcing Southwest and American to cut financial projections.

Muilenberg told a leadership conference - Boeing is taking steps to win back confidence.

SOUNDBITE (ENGLISH): DENNIS MUILENBERG, BOEING CEO, SAYING: "Pilots and leaders from 67 percent of our more than 50 MAX customers and operators around the world have participated in simulator sessions that included the software update.

Overall, our team has made 97 flights totaling a little over 159 hours of airtime with this updated software." Investors were encouraged by the update - giving the stock a bounce Thursday.

But the real test is winning over regulators.

The Federal Aviation Administration is holding a fact-finding meeting Friday with U.S. airlines that fly the 737 MAX and will later hold a joint review with regulators from around the world.

The FAA has given no hints as to when it may let the plane fly again.