United Airlines planes, including a Boeing 737 MAX 9 model, are pictured at George Bush Intercontinental Airport in Houston, Texas, U.S., March 18, 2019. REUTERS/Loren Elliott

CHICAGO (Reuters) - United Airlines, one of three U.S. carriers that operate Boeing’s 737 MAX, is “optimistic” about the U.S. manufacturer’s software update, Vice President of Corporate Safety Michael Quiello said in a statement on Wednesday.

“But, the U.S. commercial aviation system is the safest in the world because its foundation is built on rigorous data analysis and evidence-based independent oversight, and we look to the FAA to employ these tools as it reviews and certifies this software update,” Quiello added.