The McDonnell Douglas DC-10 was produced in three basic models, the Series 10 for domestic routes to 3,500 miles and the series 30 and 40 for extended range and intercontinental travel. The three-engine DC-10 incorporated improvements in propulsion, aerodynamics, structure, avionics, flight control systems and environmental compatibility that advanced industry standards. The roomy flight deck of the DC-10 had stations for a three-member crew, plus seating for two observers. Prime considerations in cockpit design were simplicity, efficiency and low crew workload.