Boeing plans to launch a second unpiloted test flight of its CST-100 Starliner crew ferry ship after software glitches last December prevented a rendezvous and docking with the International Space Station and briefly threatened the spacecraft's survival, company officials said Monday.

A review of the December flight pinpointed the causes of the problems and the steps required to correct them. No new issues were uncovered, but NASA managers said at the that time no decision had been made on whether a reflight might be required.

The Monday announcement said Boeing had "chosen to refly our Orbital Flight Test to demonstrate the quality of the Starliner system."

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"Flying another uncrewed flight will allow us to complete all flight test objectives and evaluate the performance of the second Starliner vehicle at no cost to the taxpayer," the company statement said. "We will then proceed to the tremendous responsibility and privilege of flying astronauts to the International Space Station."

Boeing's CST-100 Starliner capsule was launched on an unpiloted test flight last Dec. 20, but a major software glitch and communications trouble prevented a planned rendezvous and docking with the International Space Station. Boeing

A Boeing spokewoman said the capsule originally intended for the first piloted Starliner test flight will be used for the unpiloted reflight. She said Boeing is "working with NASA to determine an agreeable schedule for the second OFT."

While details still need to be worked out, she said in an email, "we anticipate flying the mission in the Fall of 2020." That would appear to rule out a piloted Starliner flight in 2020, but no decisions have been announced on subsequent launch targets.

Boeing and SpaceX are both building piloted astronaut ferry ships for NASA under commercial contracts valued at up to $6.8 billion. The goal is to end the agency's sole reliance on Russian Soyuz spacecraft to carry U.S. crews to and from the International Space Station.

SpaceX carried out a successful unpiloted test flight of its Crew Dragon spacecraft last year and is gearing up for a second test flight, this one with two NASA astronauts on board, in the late May timeframe.

If that flight goes well, a second, operational Crew Dragon mission with four astronauts on board could be ready for takeoff by the end of July.

Boeing's CST-100 Starliner seen on NASA television shortly after the capsule landed in New Mexico last December following a shortened test flight. NASA/Boeing

Boeing had hoped to launch a crew this year as well — but during the December OFT mission, a major software error, coupled with communications dropouts, prevented a planned rendezvous and docking with the space station.

Another software oversight could have caused a catastrophic failure during the capsule's re-entry, had it not been caught in time.

Douglas Loverro, director of spaceflight at NASA Headquarters, told reporters in March the incidents had been classified as a "high-visibility close call," a formal designation that kicks off additional government review. At that time, he said it was too soon to say whether a second test flight would be needed.

Boeing told investors earlier that it was taking a $410 million charge against pre-tax earnings in large part to cover the possible cost of another test flight.

"For us, it's not that complicated," Jim Chilton, senior vice president at Boeing Space and Launch, said in March. "Boeing stands ready to repeat an OFT (if required). ... There's not any intent on our part to avoid it. We just want to make sure that whatever we fly next is aligned with NASA's preferences. And of course for all of us, crew safety is number one."