at Gonzaga University, waiting on an appointment to the United States Military Academy, West Point, where she earned a bachelor's degree in mechanical engineering and was commissioned as an army officer in 2002.

[2] Her work on unsteady aerodynamics and flow visualization of free-to-roll non-slender delta wings was later published through the American Institute of Aeronautics and Astronautics.

She completed Command and General Staff College and the C-12 fixed wing multiengine qualification courses in 2011 and 2012.

[2] In total, McClain has logged over 2,000 hours on various aircraft type including the Kiowa Warrior, the Beechcraft C-12 Huron, the Sikorsky UH-60 Black Hawk, and the Eurocopter UH-72 Lakota.

For her first spaceflight assignment, McClain was assigned to as flight engineer to ISS Expedition 60/61, scheduled for launch aboard Soyuz MS-13 in June–July 2019, although, in January 2018, NASA astronaut Jeanette Epps was removed from the prime crew of Expedition 56/Expedition 57, resulting in her backup, Serena Aunon-Chancellor taking her place on the flight.

[12] The Expedition 58/59 trio launched aboard Soyuz MS-11 to the International Space Station at 06.32 ET (11.32 GMT) on December 3, 2018, from the Cosmodrome in Baikonur, Kazakhstan.

The launch was originally scheduled for December 20, 2018, but was rescheduled to the earlier date after the failure of Soyuz MS-10 with Expedition 57/58 on October 11, 2018.

They also removed debris from the Unity Module in preparation for the arrival of Cygnus NG-11 in April, stowing tools for the repair of the flex hose rotary coupler, and securing tiebacks on the solar array blanket boxes.

[20] On August 23, 2019, The New York Times reported that Worden filed a complaint against McClain through the Federal Trade Commission accusing her of illegally accessing financial information while residing in the International Space Station.

[20][21][22] This accusation outed McClain as a member of the LGBTQ community, making her the third known LGBT astronaut after Sally Ride[23] and Wendy B.