Ampan,
"So you and the F/O proceed to manually enter the waypoints, assuming that they are the same as on the flightplan used at the briefing – and so you don’t check the McMurdo waypoint against your chart."
The First Officer, according to Mahon's "Verdict on Erebus" had left his briefing documents at home.
Once again this fact was used by Mahon to weave a story about who collected what from whom and to whom it was all delivered.