Hot on the heels of the SpaceX Crew Dragon’s successful maiden spaceflight , the Boeing Starliner CST-100 is getting ready for its own moment in the spotlight.

Boeing is preparing to fly the spacecraft to the ISS in a mission called Orbital Flight Test (OFT). OFT will launch on a United Launch Alliance (ULA) Atlas V rocket from Cape Canaveral, Florida as early as April.

Boeing, NASA, ULA and Pentagon personnel recently performed an “integrated crew exercise”—essentially a practice run—to help prepare for launch day. The exercise took the team through a mock countdown that featured some of the technical difficulties that can occur during a real countdown.

“The team was presented with simulated issues with hardware and downrange assets to exercise troubleshooting, problem resolution procedures and the coordination that goes into adjusting the countdown as necessary,” said a NASA writeup of the exercise. “There were even simulated challenges from the weather, forcing officials to react to changing weather conditions at the pad. The exercise culminated with a successful liftoff and climb into space.”

Boeing unveils first flight-worthy Starliner.

The OST mission will give Boeing an opportunity to perform tests on hardware and verify data from earlier tests, as well as train flight controllers and mission managers. A successful OFT would open the door to a crewed flight as early as August—with Boeing still playing catch-up to rival SpaceX, which plans a crewed flight of its Crew Dragon to the ISS in July.

Boeing’s 2014 contract with NASA to develop the Starliner is valued at $4.2 billion—and a successful uncrewed flight to the ISS will be a significant milestone. Not only would it give the aerospace company something to be proud of, it could also mean NASA will have more options for taking astronauts into space. NASA has been reliant on buying passage on Russian Soyuz missions—at the cost of about $80 million per seat—since the space shuttle program ended in 2011. With the Starliner, NASA could soon be launching astronauts from home soil again.

Boeing is keen to maintain pace with SpaceX and give the Starliner its moment to shine. “There still are many critical steps to complete before launch,” said Kathy Lueders, NASA’s Commercial Crew Program manager. “We are excited about seeing the hardware we have followed through development, integration and ground testing move into flight.”

Read more about how Boeing and its competitors are preparing to take astronauts to the Moon at Who Will Win the Private Sector Space Race?