Didn't Polish LOT do something very similar in an old generation 737 possibly a 400 out of LHR.
Entered East into the FMC because that's where they mostly do all their flying on the 737, instead of West and with the IRSs not working correctly your down to STBY instrumentation.
ATC talked them down with turn right 5' left 10' etc.
We are all sky gods at home on the couch but are all just one flight away from a Disaster at work!
Correct me if I'm wrong gents.
Cheers Enos