Overshoot and lead-in

Rotary aircraft can make 90 degree turns. When the get close to the end of each flightpath the aircraft slows to a stop, turns 90 degrees and heads to the next waypoint. This is quite efficient. Fixed wing aircraft do not do this. They typically throttle up in the turns to avoid losing altitude. Depending on the aircraft it may need to fly 50 to 200 meters past the end of the waypoint to have time to turn 180 degrees around and come down the next row. Lead-in is a term for a waypoint outside of the boundary which the plane tries to hit in order to get lined up for the next pass. As shown below, overshoot to the north of the red boundary is set at 150m as shown in waypoint 3 to waypoint 4. To the south of the boundary overshoot is set at 200m as shown in waypoint 7 to waypoint 8. The Lead In is 100m as shown in waypoint 9 to 10 and 13 to 14. The amount of overshoot and lead-in change with the wind speed and wind direction. Turns are very sharp when heading into high wind. Turning downwind with a high wind speed is usually very problematic for fixed wing planes. They get blown way off course and have a hard time recovering. Always avoid turning a fixed wing plane downwind.