Shanahan served Boeing Commercial Airplanes as vice president and general manager of the Boeing 757 program, with responsibility for the design, production, and profitability of the 757 family of planes.
Shanahan oli osakonna Boeing Commercial Airplanes asepresident ning Boeing 757 projekti üldjuht, tema ülesandeks oli vastutada 757 lennukiperekonna kujunduse, tootmise ja kasumlikkuse eest.