  X-ray transients are among the most enigmatic objects in the cosmic sky. The
unpredictability and underlying nature of their transient behavior has prompted
much study in recent years. While significant progress has been made in this
field, a more complete understanding of such events is often hampered by the
delay in the rapid follow-up of any transient event. An efficient way to
mitigate this constraint would be to devise a way for near real time detection
of such transient phenomena. The Athena/Wide Field Imager (WFI), with its $40'
\times 40'$ field of view and large effective area, will detect a large number
of X-ray variable or transient objects daily. In this work, we discuss an
algorithm for the rapid on-board or ground-based detection of X-ray transients
with WFI. We present a feasibility test of the algorithm using simulated
Athena/WFI data and show that a fairly simple algorithm can effectively detect
transient and variable sources in typical Athena/WFI observations.
