Dennis Muilenburg wrote to Ethiopian Airlines and the airline industry to say Boeing had "thought about the lives lost" in two deadly 737 Max crashes.
The pilots of the Southwest Airlines Boeing 737 Max reported problems with their CFM Leap-1B engines.
Other reports have described the pilot's final moments, which are said to have been spent working through a technical manual in search of a solution.
Garuda Indonesia became the first airline to attempt to cancel its order for Boeing's 737 Max 8 aircraft, a decision the airline announced on Friday.
New reports suggest that Boeing pushed the 737 Max to compete with Airbus.
The Justice Department has subpoenaed Boeing as part of a criminal investigation into the certification and marketing processes for the 737 Max, CNN reported.
EU and Canadian regulators plan to review an upcoming software update to the Boeing 737 Max due in the wake of the deadly Ethiopian Airlines crash.
The investigation into October's Lion Air crash has taken on new significance since the fatal crash of an Ethiopian Airlines 737 Max 8 plane.
The investigation into the Lion Air crash has taken on new significance since the fatal crash of an Ethiopian Airlines 737 Max 8 plane.
This development comes as Boeing is reeling from the fallout over its 737 Max series, which has now been grounded in several countries.
Ethiopia's transport minister reportedly told The Wall Street Journal that the black boxes from both crashes showed similar data.
China's aviation authority issued a notice to ground all domestic Boeing 737 Max 8 planes in light of the deadly Ethiopian Airlines crash.