Various validation tests began on test articles in 2011 and continued on actual spacecraft starting in 2019.
Abort and drop tests (foreground) frames the Starliner (background) in 2012. During testing, the helicopter dropped the capsule from about to test its parachutes and airbags. In September 2011, Boeing announced the completion of a set of ground
drop tests to validate the design of the airbag cushioning system. 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 altitude. The airbags, manufactured by ILC Dover, are deployed by filling with a mixture of compressed nitrogen and oxygen gas, not with the pyro-explosive mixture sometimes used in automotive
airbags. The tests were carried out in the
Mojave Desert of southeast California, at ground speeds between in order to simulate crosswind conditions at the time of landing. Bigelow Aerospace built the mobile test rig and conducted the tests. In April 2012, Boeing dropped a mock-up of its Starliner over the
Nevada desert at the
Delamar Dry Lake,
Nevada, successfully testing the craft's three main landing parachutes from . 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
Orbital Flight Test was scheduled for spring 2019. 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 first crewed flight (
Boe-CFT) was scheduled for summer 2019, pending test results from
Boe-OFT. It was planned to last 14 days and carry one NASA astronaut and one Boeing test pilot to the ISS. On April 5, 2018, NASA announced that the first planned two-person flight, originally slated for November 2018, was likely to occur in 2019 or 2020. A serious incident occurred during a hot-fire test in June 2018. A design flaw in the propellant system left four of eight valves open, leading to the release of over of toxic
monomethylhydrazine propellant, resulting in a fireball that engulfed the equipment. The incident was reportedly exacerbated by animosity with the propulsion system subcontractor, Aerojet Rocketdyne, who Boeing refused to pay for design changes. While it informed NASA of the incident, Boeing attempted to keep the incident quiet, even withholding information from the astronauts involved in the project. In October 2018, the first unpiloted orbital mission was delayed to April 2019, and the first crew launch was rescheduled to August 2019. In March 2019,
Reuters reported that these test flights had been delayed by at least three months, and in April 2019 Boeing announced that the unpiloted orbital mission was scheduled for August 2019. abort engines during the
Boeing Pad Abort Test in November 2019. In May 2019, all major hot-fire testing, including simulations of low-altitude abort-thruster testing, was completed using a full up-to-service module test article that was "flight-like," meaning that the service module test rig used in the hot-fire testing included fuel and helium tanks, reaction control system, orbital maneuvering, and attitude-control thrusters, launch abort engines and all necessary fuel lines and avionics that will be used for crewed missions. This cleared the way for the pad abort test and the subsequent uncrewed and crewed flights. A pad abort test took place on November 4, 2019. Landing was, however, deemed safe, and the test a success. Boeing did not expect the malfunction of one parachute to affect the Starliner development schedule.
First orbital flight test (uncrewed) on June 19, 2018 in
New Mexico following an uncrewed Orbital Flight Test in December 2019. The uncrewed Boeing Orbital Flight Test (OFT) launched on December 20, 2019, bearing an
Anthropomorphic Test Device nicknamed "Rosie the Rocketeer" and clothed in Boeing's blue IVA spacesuit as well as a Plush toy of Jebediah Kerman from
Kerbal Space Program. It landed two days later, having nearly ended in catastrophic failure. The mission was ultimately declared a partial failure. As the capsule was prepared for re-entry, another software error was discovered; it could have caused a catastrophic collision between the service module and crew capsule. The spacecraft landed at
White Sands Missile Range,
New Mexico, two days after launch. After its landing, NASA astronaut
Sunita Williams named the spacecraft
Calypso after the
research vessel used by
oceanographic researcher
Jacques Cousteau. After the mission, Boeing vice president John Mulholland acknowledged that the company had not conducted integrated end-to-end tests for the entire mission, but had instead performed tests of smaller segments. This approach contributed to the software errors that led to the near-catastrophic failures during the flight test. Mulholland insisted that Boeing cut no corners, and that end-to-end tests were not omitted to save money. NASA was also faulted for not pressing Boeing to conduct an end-to-end test.
Second orbital flight test (uncrewed) in
New Mexico following OFT-2 in May 2022 Because the first OFT did not achieve its objectives, Boeing officials said on April 6, 2020 that the Starliner crew capsule would fly a second uncrewed demonstration mission,
Boeing Orbital Flight Test 2 (OFT-2), before flying astronauts. NASA said that it had accepted a recommendation from Boeing to fly a second unpiloted mission.
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 said that it would fund the unplanned crew capsule test flight "at no cost to the taxpayer". 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. Boeing officials said on August 25, 2020 that they set the stage for the first Starliner demonstration mission with astronauts in mid-2021. 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. This re-entry cover is hinged, like the SpaceX design. Teams also installed the OFT-2 spacecraft's propellant heater, thermal-protection tiles, and the airbags used to cushion the capsule's landing. The crew module for the OFT-2 mission began acceptance testing in August 2020, which is designed to validate the spacecraft's systems before it is mated with its service module, according to NASA. The uncrewed test continued to slip, with the OFT-2 uncrewed test flight being scheduled for March 2021 and the crewed flight targeted for a launch the following summer. The launch date of OFT-2 moved again with the earliest estimated launch date set for August 2021. During the August 2021 launch window some issues were detected with 13 propulsion-system valves in the spacecraft prior to launch. The spacecraft had already been mated to its launch rocket, United Launch Alliance's (ULA)
Atlas V, and taken to the launchpad. Attempts to fix the problem while on the launchpad failed, and the rocket was returned to the ULA's VIF (Vertical Integration Facility). Attempts to fix the problem at the VIF also failed, and Boeing decided to return the spacecraft to the factory, thus cancelling the launch at that launch window. There was a commercial dispute between Boeing and Aerojet Rocketdyne over responsibility for fixing the problem. The valves had been corroded by intrusion of moisture, which interacted with the propellant, but the source of the moisture was not apparent. By late September 2021, Boeing had not determined the root cause of the problem, and the flight was delayed indefinitely. Through October 2021, NASA and Boeing continued to make progress and were "working toward launch opportunities in the first half of 2022", In December 2021, Boeing decided to replace the entire service module and anticipated OFT-2 to occur in May 2022. The OFT-2 mission launched on May 19, 2022. It again carried Rosie the Rocketeer test dummy suited in the blue Boeing inflight spacesuit. Two Orbital Maneuvering and Attitude Control (OMAC) thrusters failed during the orbital insertion burn, but the spacecraft was able to compensate using the remaining OMAC thrusters with the addition of the Reaction Control System (RCS) thrusters. A couple of RCS thrusters used to maneuver Starliner also failed during docking due to low chamber pressure. Some thermal systems used to cool the spacecraft showed extra cold temperatures, requiring engineers to manage it during the docking. On May 22, 2022, the capsule docked with the International Space Station. On May 25, 2022, the capsule returned from space and landed successfully. During reentry one of the navigation systems dropped communication with the GPS satellites, but Steve Stich, program manager for NASA's Commercial Crew Program, said this is not unexpected during reentry.
Third orbital flight test (crewed) Starliner's crewed flight test was intended to be the capsule's final evaluation before entering regular NASA service. The mission plan called for launching two astronauts, commander
Barry Wilmore and pilot
Sunita Williams, to dock with the ISS for about a week and return to Earth roughly eight days later. During approach to the ISS, five of spacecraft's eight aft-facing RCS thrusters failed. After the first two thrusters failed, Wilmore took manual control, noting the vehicle was less responsive than during a test the previous day. NASA waived standard flight rules to allow docking despite the degraded conditions. Eventually, four thrusters failed, resulting in a loss of full
six degrees of freedom (6DOF) attitude control. The astronauts later described the situation as "very precarious." A post-mission investigation report released in February 2026 found that the thruster failures were most likely caused by a combination of oxidizer heating and valve seal deformation. Elevated temperatures inside the doghouse containing the thrusters, generated by thruster firings, caused the nitrogen tetroxide oxidizer (NTO) to partially vaporize before reaching the combustion chamber, creating gas bubbles and reducing flow. At the same time, exposure to NTO, heat, and pressure caused the
Teflon seals within the oxidizer valves to deform and expand, further restricting oxidizer flow to the engines. While the on-orbit issues were replicated in tests at White Sands using hardware intended for future flights, they could not be reproduced on the in-flight Starliner. During the mission, seven of the eight helium manifolds in the service module developed leaks. The investigation determined the most likely cause was incompatibility between the valve materials and NTO, combined with poorly fitting O-rings. The spacecraft returned uncrewed and landed safely at
White Sands Missile Range on 7September at 04:01:35UTC (6September, 11:01:35pm
MDT, local time at the landing site), about six hours after it undocked from the ISS. The mission, originally scheduled for 2017, had already been plagued by delays due to parachute system issues and wiring concerns. A launch attempt on May 6, 2024, was scrubbed due to an oxygen valve problem on the rocket. Subsequently, a helium leak in the service module further delayed the mission. Another attempt on June 1 was scrubbed due to a ground computer hardware fault. Starliner launched on June 5 at 14:52 UTC (10:52am EDT). During reentry, Starliner experienced a brief navigation glitch and the failure of a crew module orientation thruster, which were unrelated to the earlier RCS issues. The investigation determined that the orientation thruster likely failed due to corrosion caused by carbazic acid formed from residual propellant and carbon dioxide. The failure of this single thruster reduced the system to zero fault tolerance. The report noted that the crew module orientation system lacked the required two-fault tolerance for deorbit burns, a design limitation that had existed since early development but was not identified until the crewed flight test pre-launch.
Starliner-1 (uncrewed) Because NASA was unable to certify Starliner based on the crewed flight test, Boeing and NASA agreed that the next flight, Starliner-1, would not carry crew and that it would serve as a test flight for purposes of certification. == Commercial use ==