In the context of aircraft turnaround processes, this paper illustrates how simulation can be used not only to analyze critical activities and paths, but also to generate the associated survival functions ' thus providing the probabilities that the turnaround can be completed before a series of target times. After motivating the relevance of the topic for both airlines and airports, the paper reviews some related work and proposes the use of Monte Carlo simulation to obtain the critical paths of the turnaround process and generate the associated survival function. This analysis is performed assuming stochastic completion times for each activity in the process - which contrast with current practices in which deterministic times are usually assumed. A series of numerical experiments considering the Boeing 737-800 aircraft are carried out. Different levels of passengers' occupancy are analyzed, as well as two alternative designs for the turnaround stage.