Many rebreather accidents and fatalities could have been prevented with the use of assembly and pre-dive checklists. There is nothing particularly difficult about assembling a rebreather, however there are many small yet important steps in the process. A small oversight such as forgetting to re-install an O-ring can have disastrous consequences.
We are all human and as such are susceptible to distraction and lapses in memory. There is overwhelming evidence pointing to the efficacy of checklists in preventing errors in complex technical procedures. It is highly recommended that you use a written or digital checklist for both assembly and pre-dive checks before every dive. See the Checklists section in this manual for assembly and pre-dive checklists.