Abstract: This paper proposes a timing analysis technique that gives practical support to the industrial systems engineering process for large-scale, distributed real-time systems. The technique, known as reservation-based timing analysis (RBA), gives support throughout the life-cycle of the system, from the early stages of system development through to implementation stages and later in-service upgrades. RBA allows the timing properties of the system to be validated incrementally throughout system development and upgrade. This gives greater control over the costs associated with the development and upgrade of the real-time properties of the system.