Markov process based time limited dispatch analysis with constraints of both dispatch reliability and average safety levels

Time Limited Dispatch (TLD) allows a degraded redundant system to operate for a limited length of time before it is sent for repair. Existing TLD analysis methods do not consider dispatch reliability requirement as a constraint, thus unacceptable flight delays or cancellations may be experienced when aircraft are dispatched following the intervals determined by existing methods. In this paper, an improved TLD analysis method with constraints of both dispatch reliability and average safety levels is proposed based on Markov process analysis. Dispatch strategies for multiple fault TLD models are proposed, the average safety level is redefined, and both the dispatch reliability and the average safety level are expressed by dispatch intervals based on the Markov processes. Finally, examples illustrate the advantages of the proposed method. The results show that the requirements for both dispatch reliability and average safety level are ensured when aircraft are dispatched following the intervals determined by the proposed method.