Before revision: When μ >> λ, the preceding formula is often approximated to: Q = λ / μ Calculations using unavailability Often fault trees and reliability block diagrams will use unavailability of the various components in the calculation of the top level failure rates through AND gates or parallel redundant components.
After revision: When μ >> λ, the preceding formula is often approximated to: Q ≅ λ / μ Calculations using unavailability Often fault trees and reliability block diagrams will use unavailability of the various components in the calculation of the top level failure rates through AND gates or parallel redundant components.