The most difficult to assess when you are about to overtake another vehicle is where the meeting with an oncoming vehicle will occur.
Meetings with oncoming vehicles usually occur much earlier than we think they will. If you are going to overtake another vehicle or turn left on a country road and misjudge the distance to an oncoming vehicle, or the oncoming vehicle's speed, the consequences can be devastating.
Always expect meetings with oncoming vehicles to come earlier than you think. Do not take chances – if you feel uncertain of where a meeting will take place, it is better to wait with the overtaking manoeuvre or the left turn.