Large-scale vehicle simulations in which human subjects are exposed to realistic environmental profiles are well within the engineering state-of-the-art. The Boeing Multiple-Stress Laboratory is capable of exposing subjects to heat, noise, vibration, and altitude, while measuring their performance and physiology. Data have been obtained on simulations relative to fixed-wing aircraft, helicopters, and three-stage boosters. Exposure periods have ranged from a minimum of 9 minutes to a maximum of 6 hours. Boeing experience, in the past 4 years, has evidenced that a facility of this type can provide an effective bridge between analytical studies and the operational situation. Inherently flexible, such a facility can support a wide variety of development programs.