Tammie Jo Shults was accepted by the Navy for Aviation Officer Candidate School at Naval Air Station Pensacola. After completing the twelve-week course and receiving her commission as an Ensign on June 21, 1985, Shults attended flight training, also at NAS Pensacola, where she trained and qualified for her pilot's wings in the T-34 .

After Pensacola, Shults was stationed at Naval Air Station Chase Field as a flight instructor for the T-2 Buckeye. She later qualified in the A-7 Corsair II with training (RAG) squadron VA-122 at Naval Air Station Lemoore. Her next assignment was VAQ-34, a Tactical Electronic Warfare Squadron at the Pacific Missile Test Center located at Point Mugu, California. When the squadron relocated to NAS Lemoore in 1991, Shults became an instructor under the command of CAPT Rosemary Mariner, the first woman to command an operational air squadron. Shults became one of the first female naval aviators to qualify in the F/A-18 Hornet when the squadron transitioned from the EA-6B Prowler.

During Operation Desert Storm, the combat exclusion policy at that time prevented women from flying combat sorties, so Shults flew training missions as an instructor aggressor pilot for naval aviators. She finished her tour of duty in March 1993.

In December 1995, she was promoted to Lieutenant Commander (LCDR), then transitioned to the Navy Reserve, where she flew the F/A-18 Hornet and EA-6B Prowler until August 2001. 

After leaving the Navy, Shults joined Southwest Airlines as a pilot, flying a part-time schedule of 8–10 days per month so that she could also raise a family following her marriage to fellow naval aviator Dean Shults.

On April 17, 2018, while Shults was captain in command of Flight 1380 from New York to Dallas, an engine fan blade on the Boeing 737 failed and flying debris damaged the left side of the fuselage and one side window; the window failed, causing the plane to decompress. One passenger was partially sucked through the damaged window and was later pronounced dead at the hospital. Shults made an emergency descent and landed in Philadelphia. Her actions, calm demeanor, and competence during the emergency were noted by Southwest Airlines officials and passengers as well as Chesley Sullenberger, another commercial airline and former military pilot who controlled a similar situation in 2009 on US Airways Flight 1549.

Shults later revealed that she had not intended to be the pilot of that flight, but had swapped the shift with her husband.

In 1994, she married Dean Shults, at the time a fellow naval aviator in the A-7 Corsair II, who also joined Southwest Airlines as a pilot that year. Together, they have two children. The couple lives in Boerne, Texas. Shults is a devout Christian who teaches Sunday school, and helps the needy, such as internally displaced persons from Hurricane Rita.

Shults wrote a book about Southwest Airlines flight 1380, Nerves of Steel, which was released in the United States on October 8, 2019.