The US space agency convened a short-notice news conference and released a 300-page report examining the technical and oversight failures behind Starliner’s first crewed flight in 2024, a high-profile mission that kept Nasa astronauts Butch Wilmore and Suni Williams on the ISS for nine months for a test mission initially planned to last roughly a week.

“Starliner has design and engineering deficiencies that must be corrected, but the most troubling failure revealed by this investigation is not hardware,” Isaacman wrote in a letter to Nasa employees, which he posted in full on X.

“It is decision-making and leadership that, if left unchecked, could create a culture incompatible with human spaceflight,” he added, echoing findings in the report’s “cultural and organisational” section.

Nasa retroactively classified the Starliner mission as a “Type A” mishap, the agency’s most severe category of mission failure, triggered by factors such as damage to a spacecraft exceeding US$2 million or a crew member’s death or permanent disability.

Boeing has spent tens of millions of dollars on efforts to fix Starliner after the mission. Wilmore and Williams, both veteran test pilots and astronauts, safely returned to Earth last year on a SpaceX craft after their faulty Starliner capsule returned empty.

“First and foremost, we’re trying to send a message about what is the right and wrong way to handle situations like this so that they do not recur,” Isaacman told reporters.

The report, which was completed in November, lists four previously known technical anomalies that led to mission-failure status, including Starliner’s propulsion system glitches that complicated its ability to dock with the ISS in the first hours of its mission.