The agency said in a statement that it closed its command post at the airport Monday as the inquiry "pivots this week from the on-scene phase."
Several NTSB teams involved in the investigation have returned to Washington, the agency said, though at least one remained Monday to complete interviews with first responders.
Investigators into the July 6 crash have spent hours talking to witnesses and the flight crew, as well as combing the wreckage, gathering recorders from the aircraft and studying the runway.
"The next phase of the investigation will include additional interviews, examination of the evacuation slides and other airplane components, and more in-depth analysis of the airplane's performance," the NTSB statement said.
The remnants of the
NTSB Chairwoman Deborah A.P. Hersman said last week that although the agency typically takes 12 to 18 months to complete its reports, she hoped the
"It's going to be a high priority for our agency," she said.
Three people -- high school students from China -- were killed and more than 180 others were injured after the jet struck a seawall and slammed into a runway on its approach to SFO. Investigators are looking at why the plane's speed and altitude fell far out of the normal range for landing before the crash.