Originally Posted by
Teal
I once watched a BA 747 turn 50° after an incorrect waypoint input. It occurred in darkness and the flightcrew were completely oblivious until asked to confirm their position (heading east to the South Pacific off the New South Wales coast when they should have been tracking to Sydney over land). I can imagine a crew under pressure easily making a similar mistake with no visual references to alert them to a navigation error.
Oddly the passengers watching the inflight map, would see the plane heading out to sea. Human mistakes are made, when the information they see in front of them they have mentally checked it off as OK. Once checked off, it takes fresh eyes or very good training to reassess the data to reconfirm it is actually correct.