The aggregation of web services in order to achieve a common goal is a basic concept in Service Oriented Architectures (SOA). This paper demonstrates OGC Web Services (OWS) aggregation based on a simulated bomb threat scenario which is a possible disaster management example. Web services are aggregated based on the OGC Web Processing Service (WPS) interface. Here the concept of a “Composite-WPS” is introduced and used to invoke all other services involved. The presented approach is compared to the use of BPEL which is an orchestration language with some technical pitfalls when applied to the orchestration of OWS.