Abstract-- We propose a formal definition for the timed asynchronous distributed system model. We present extensive measurements of actual message and process scheduling delays and hardware clock drifts. These measurements confirm that this model adequately describes current distributed systems such as a network of workstations. We also give an explanation of why practically needed services, such as consensus or leader election, which are not implementable in the time-free model, are implementable in the timed asynchronous system model. Keywords-- timed model, system model, failure model, distributed systems, asynchronous systems, synchronous systems, measurements, communication by time.