During the Crew Flight Test, launched in June 2024, the Starliner's thrusters malfunctioned on approach to the ISS and NASA concluded that it was too risky to return its astronauts to Earth aboard the spacecraft, which landed uncrewed in September 2024.

Boeing had lobbied NASA for a sole-source contract, arguing that it needed the program's full budget for the successful development of Starliner.

[15] While William H. Gerstenmaier, NASA's human exploration lead, had considered the Starliner proposal as stronger,[16] he was hesitant to award a sole-source contract.

The multi-year Commercial Crew Program had been designed to foster competition and redundancy, and Gerstenmaier believed that selecting just one company would undermine these goals.

In November 2015, NASA announced that it had dropped Boeing from consideration in the separate multibillion-dollar Commercial Resupply Services competition to fly cargo to the International Space Station.

[21] The design draws upon Boeing's experience with NASA's Apollo, Space Shuttle, and ISS programs, as well as the Orbital Express project.

[23][24][25] Boeing modified the Starliner design prior to OFT-2, adding a hinged re-entry cover below its expendable nosecone for additional protection of the docking port during atmospheric entry.

There are four primary landing locations, including two sites inside the White Sands Missile Range in New Mexico, the Willcox Playa in Arizona and the Dugway Proving Ground in Utah.

Despite being initially awarded significantly more funding, Boeing has faced substantial budget overruns for the Starliner program, exceeding $2 billion as of February 2025[update].

[42] In August 2024, after the setbacks experienced during the Crew Flight Test, NASA Administrator Bill Nelson stated that Boeing CEO Kelly Ortberg committed to continuing the Starliner program.

The airbags are located underneath the heat shield of the Starliner, which is designed to be separated from the capsule while under parachute descent at about 5,000 ft (1,500 m) altitude.

The tests were carried out in the Mojave Desert of southeast California, at ground speeds between 10 and 30 mph (16 and 48 km/h) in order to simulate crosswind conditions at the time of landing.

[48] Boeing reported in May 2016 that its test schedule would slip by eight months in order to reduce the mass of the spacecraft, address aerodynamics issues anticipated during launch and ascent on the Atlas V rocket, and meet new NASA-imposed software requirements.

The booster for this Orbital Flight Test, an Atlas V N22 rocket, was assembled at United Launch Alliance's (ULA) facility at Decatur, Alabama by the end of 2017.

The incident was reportedly exacerbated by animosity with the propulsion system subcontractor, Aerojet Rocketdyne, who Boeing refused to pay for design changes.

[54][55] In March 2019, Reuters reported that these test flights had been delayed by at least three months,[56] and in April 2019 Boeing announced that the unpiloted orbital mission was scheduled for August 2019.

The Washington Post reported that the second orbital flight test, with much the same objectives as the first, was expected to launch from Cape Canaveral "sometime in October or November 2020".

Boeing told investors earlier in 2020 that it was taking a US$410 million charge against its earnings to cover the expected costs of a second unpiloted test flight.

[26] Boeing modified the design of the Starliner docking system prior to OFT-2 to add a re-entry cover for additional protection during the capsule's fiery descent through the atmosphere.

[26][27][28] On November 10, 2020, NASA's Commercial Crew Program manager Steve Stich said that the second orbital flight test would be delayed until first quarter 2021 due to software issues.

[98] Once in orbit and on approach to the ISS during this flight test, both the automated systems and astronauts taking manual control during the docking sequence were instructed to repeatedly fire the RCS thrusters.

This stress testing revealed performance degradation in the thrusters, leading the spacecraft software to consider five of them damaged and unusable, and five separate helium leaks were detected in the service module.

[116] NASA Administrator Bill Nelson has stated that Boeing CEO Kelly Ortberg has committed to continuing the Starliner program despite the setback.

After NASA decided to end the Starliner test flight without a crew on board, the company refused to answer questions from journalists, instead opting to release only brief statements.

[115] Under the CCP, Boeing owns and operates the Starliner capsules, allowing the company to offer non-CCP commercial flights if they do not interfere with NASA missions.

[118] In October 2021, Blue Origin, Boeing, and Sierra Nevada Corporation announced plans for a commercial space station called Orbital Reef.

Delta IV is retired and no more are available,[126] the Falcon 9 is owned by crewed launch competitor SpaceX, and the Vulcan Centaur has not yet been human-rated, testing Boeing would have to pay for.

Two engines allow the rocket to fly a gentler and flatter trajectory to minimize the G-forces experienced by the astronauts and ensures the capsule can abort at any time, returning the crew to Earth in case of a problem.

[128][129] After passing through the stages of max q, SRB jettison, booster separation, Centaur ignition, nosecone and aeroskirt jettison, it releases the Starliner spacecraft at stage separation, nearly 15 minutes after lift-off on a 112 mi × 45 mi-high (181 km × 72 km) suborbital trajectory, just below the orbital velocity needed to enter a stable orbit around Earth.

After separating from the Dual Engine Centaur, the Starliner's own thrusters, mounted on its service module, boost the spacecraft into orbit to continue its journey to the International Space Station.