NASA has officially classified Boeing’s CST-100 Starliner crewed flight test as a Type A accident, the agency’s highest accident designation, following the release of an independent investigation into the troubled spacecraft’s 2024 mission.
The report, completed in November 2025 by a program research team established earlier that year, investigated the technical, organizational, and cultural factors contributing to propulsion anomalies and loss of maneuverability during Starliner’s first crewed flight to the International Space Station (ISS).
Starliner will launch on June 5, 2024, carrying NASA astronauts Butch Wilmore and Suni Williams, and was originally planned as an eight- to 14-day test mission. But as the spacecraft approached the ISS, a propulsion system malfunction complicated the docking process and extended its stay in orbit while engineers assessed the problem.
The mission ultimately lasted 93 days. After ground testing and data review at the White Sands Test Facility, NASA elected to return the spacecraft to Earth without a crew. Starliner landed autonomously at White Sands Space Harbor in New Mexico in September 2024. Wilmore and Williams later returned aboard SpaceX’s Crew 9 mission in March 2025.
NASA Administrator Jared Isaacman acknowledged both technical and managerial shortcomings in a statement accompanying the report’s release.
“While Boeing was building Starliner, NASA accepted it and launched two astronauts into space,” he said. “Beyond the technical issues, it is clear that NASA has authorized the overarching programmatic objective of having two providers capable of transporting astronauts to and from orbit to influence engineering and operational decisions.”
This reference highlights a central tension within NASA’s commercial crew program: maintaining two independent crew transportation providers, Boeing and SpaceX, to ensure redundancy and competition. The researchers found that this strategic objective was the basis of the program and may have shaped decision-making about risk before and during the mission.
The study identified what NASA described as an interplay of hardware failures, qualification gaps, leadership failures, and cultural breakdown. The spacecraft eventually regained control before docking, and no one was injured, but it temporarily lost control, creating a situation inconsistent with NASA’s safety standards for human spaceflight.
In NASA’s accident classification system, the Type A designation reflects accidents with high-risk potential outcomes and significant financial consequences. Although the crew members were safe, authorities determined the situation met the highest grade criteria because of the potential for more serious consequences.
NASA and Boeing have been working together to address the technical flaw since the spacecraft’s return, and root cause analysis continues. The agency said it would incorporate the study’s recommendations before approving future Starliner flights.
The findings represent a setback for Boeing’s long-delayed entry into flight crew change missions. SpaceX’s Crew Dragon has been conducting regular astronaut transport flights since 2020, but Starliner has repeatedly faced software, valve and propulsion-related challenges on both unmanned and manned test missions.
NASA has said it will not authorize further Starliner missions until corrective measures are implemented and verified. The agency calls the report part of a broader commitment to transparency and leadership accountability in the human spaceflight program.
The pace of Starliner’s future missions remains uncertain, as does the impact of accident classification on contract milestones within the civilian crew program. What is clear is that NASA’s dual-provider strategy, aimed at reducing dependence on a single contractor, is facing new scrutiny over how it intersects with competitive and schedule pressures and safety oversight.
For now, Starliner’s return to service depends on demonstrating not just technical fixes but organizational changes that can restore confidence in the program’s safety culture.
The Boeing Starliner spacecraft that launched NASA crew flight test astronauts Butch Wilmore and Suni Williams to the International Space Station is pictured docking in the forward port of the Harmony module on July 3, 2024. This view is from the window of SpaceX’s Dragon Endeavor spacecraft, which is docked in a port adjacent to Starliner.
Credit: NASA