Highly Accelerated Stress Screens (HASS) use the highest possible stresses, frequently well above qualification test levels, to reduce the time required to conduct the screen. HASS is based on the principle that many stimuli exhibit an exponential acceleration of flaws on a system. These stimuli enable the duration of the stress to be reduced (assuming the correct stress is applied), which in turn severely diminishes the screening equipment and manpower required. 
HASS cannot be used if Highly Accelerated Life Testing (HALT) has not been applied to the affected items during design. In such cases, “normal” Environmental Stress Screening (ESS) should be used.