  We propose a new framework to facilitate dynamic assurance within a safety
case approach by associating safety performance measurement with the core
assurance artifacts of a safety case. The focus is mainly on the safety
architecture, whose underlying risk assessment model gives the concrete link
from safety measurement to operational risk. Using an aviation domain example
of autonomous taxiing, we describe our approach to derive safety indicators and
revise the risk assessment based on safety measurement. We then outline a
notion of consistency between a collection of safety indicators and the safety
case, as a formal basis for implementing the proposed framework in our tool,
AdvoCATE.
