Taxi, takeoff, and landing. The pros stay on centerline unless otherwise appropriate for safety. Note that the runway centerline is marked by the dashed white line; not the yellow taxiway indicator lines. The yellow taxi indicator lines let you know that you are coming up on a taxiway; the yellow line will be on the same side of the dashed white line as the upcoming taxiway. While on the runway hold the dashed white line, not the yellow line(s).