PBN APP Failure RNAV

If the approach mode fails to engage or the integrity monitoring fails then the RNAVRNAV —Radio Navigation equipment is no longer effective, so you would have to revert to a basic procedure. A CDICDI —Course Deviation Indicator out by more than half full scale deflection should, and a TCAS advisory might, result in a total abandonment of the approach, not just a switch to a different one. An engine failure would have no effect and you should continue the approach.