The wind slows or speeds up the aircraft, requiring power adjustments, and changes its ground track, requiring course adjustments. In weather, the wind may be v

The wind slows or speeds up the aircraft, requiring power adjustments, and changes its ground track, requiring course adjustments. In weather, the wind may be varying as you fly, requiring constant adjustments. When flying by instruments you have to do those adjustments based on what you see on the instruments as there is no outside reference.