We propose a new protocol that can be used to implement a partitionable membership service for timed asynchronous systems. The protocol is fail-aware in the sense that a process p knows at all times if its approximation of the set of processes in its partition is up-to-date or out-of-date. The protocol minimizes wrong suspicions of processes by giving processes a second chance to stay in the membership before they are removed. Our measurements show that the exclusion of live processes is rare and the crash detection times are good. The protocol guarantees that the memberships of two partitions never overlap.