She is a nationally renowned speaker and has presented at corporations, government agencies, civic organizations, conferences, and colleges around the country on technology and aerospace innovation, as well as on gender and diversity.

Upon Simpson's appointment to the position of senior technical advisor in the Bureau of Industry and Security in 2010, she became the first openly transgender woman political appointee of any presidential administration.

In 1988 she added a multi-engine class rating to her commercial license to qualify for transfer to Hughes Missile Systems as a project test engineer and pilot.

Simpson upgraded to an airline transport pilot (ATP) license in 1994 after adding multi-engine to her flight instructor ratings in 1991.

While an undergraduate, Simpson spent her summers working as a student engineer in the customer service organization on the DC-8/DC-9/DC-10 electrical systems at the Douglas Aircraft facility in Long Beach, and on the AH-64 Apache Target Acquisition and Designation Sight/Pilot Night Vision Systems at Hughes Helicopter Company in Marina Del Rey.

She was hired by Hughes Electron Dynamics Division in Torrance, California, in 1983 as an engineer and program manager.

Simpson also contributed to the development and/or testing of numerous operation missile systems including Maverick, AMRAAM, Standard, Phalanx, TOW, RAM, JAGM, ACM, HARM, JSOW, MALD, ESSM, SilentEyes, Sidewinder, Sparrow, Paveway and Tomahawk.

Completing her public service with the Defense Department, she joined Airbus Americas in 2018 as the vice president for research and technology.

In this role, she is responsible for coordinating technology development, research activities, and innovation for Airbus in the Western Hemisphere.

[14] Simpson served as a commissioner on the City of Tucson Gay, Lesbian, Bisexual and Transgender Commission from 2001 until 2008, representing Councilwoman Carol West.

She won the Democratic primary with over 57% of the vote, but was unsuccessful in the general election where she finished third, receiving 20% in the best two of four contest.

In late 2009, Simpson accepted an appointment by the Obama administration,[18] where she served in the Department of Commerce as the senior technical adviser to the Bureau of Industry and Security.

[citation needed] Simpson is a fellow of the American Institute of Aeronautics and Astronautics, and served on its Systems Engineering Technical Committee from 2007 to 2009.