Sociotechnical systems are rapidly becoming more and more complex due to technological advancements and increasing interconnectivity. Today, many of these systems are embedded in temporary organisations (TO). The complex interconnectivity characterising a TO increases the risk of adverse work situations emerging in unexpected ways. This chapter focuses on TOs operating in high-hazard environments involving high capital assets and operations in which failure can have severe consequences—here referred to as complex temporary organisations (CTOs). Based on an empirical study aimed at understanding how these organisations sustain their operational reliability, this chapter discusses the everyday realities in a CTO with regard to collaboration, unexpected events and governance. The purpose of this chapter is to introduce the organising complexity in a CTO and illustrate that by focusing on how these organisations work rather than how they fail, a world of untapped learning opens up, offering generous scope for cross-sectoral learning.