Abstract

In this article, the staff pre-warning delay concept is developed: the time between staff becoming aware of an incident by receiving a pre-alarm, or as a result of other cues, and the raising of a general alarm. This represents the potential delay in staff response as they interpret the cues received and engage in various response behaviors before warning the population and raising a general alarm; a delay that may be procedural and/or cognitive. The theoretical basis for this concept is discussed, examples of incidents involving this delay described and data from experiments and incidents examined to help demonstrate and estimate the impact and the effects upon the available safe escape time/required safe escape time calculation. Hypothetical examples of how pre-warning delay can influence required safe escape time are presented, along with a discussion of the aspects of emergency procedures that are particularly susceptible to this type of delay. A framework for understanding these susceptibilities is suggested, together with proposals for dealing with this aspect in engineering designs so as to evaluate and minimize its impact on escape time. This concept is considered important as the exclusion of a delay from the engineering design may lead to artificially optimistic results being produced.