Boeing’s CST-100 Starliner spacecraft completed a safety milestone on Monday in an end-to-end test of its abort system.

Boeing’s CST-100 Starliner’s four launch abort engines and several orbital maneuvering and attitude control thrusters ignited on Monday morning in the company’s Pad Abort Test, pushing the spacecraft away from the test stand with a combined 160,000 pounds of thrust, from Launch Complex 32 on White Sands Missile Range in New Mexico.

The capsule accelerated to 650mph in just 5 seconds during a demonstration of its escape system.

A pitcharound maneuver rotated the spacecraft into position for landing as it neared its peak altitude of approximately 4,500 feet.

After one minute, the heat shield was released and airbags inflated, and the Starliner eased to the ground beneath its parachutes.

The test was designed to verify each of Starliner’s systems will function not only separately, but in concert, to protect astronauts by carrying them safely away from the launch pad in the unlikely event of an emergency prior to liftoff. This was Boeing’s first flight test with Starliner as part of NASA’s Commercial Crew Program to return human spaceflight launches to the International Space Station from American soil.

The test proceeded nominally until the main parachutes deployed—only two rather than three emerged from the capsule as it descended to the desert floor. During the webcast, both Boeing's Jessica Landa and NASA's Dan Huot said the deployment of two parachutes fell within the safety requirements of the system, and that this result was "within the bounds" of this test.

“Tests like this one are crucial to help us make sure the systems are as safe as possible,” said Kathy Lueders, NASA’s Commercial Crew Program manager. “We are thrilled with the preliminary results, and now we have the job of really digging into the data and analyzing whether everything worked as we expected.”

Both Boeing and SpaceX have had issues with parachutes during their test programs and have had to change their chute designs.

Boeing’s next mission, called Orbital Flight Test, will launch an uncrewed Starliner spacecraft to the station on a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station’s Space Launch Complex 41. Launch is targeted for Dec. 17.