Lockheed Martin Second Largest Employer in Tarrant County. Lockheed Martin located in the west side of Fort Worth is Second Largest Employer in Tarrant County. An estimated 15,900 people work at the massive mile long plant. The plant known as Air Force Plant 4 is on a 602- acre government- owned contractor-operated aircraft manufacturing facility. The plant has been in continuous operation producing aircraft since 1942. Aircraft built at the plant include B-24, B-32.B-36, B-58, F-111, F-16, F-22 and the F-35. For Employment