For steep terrain (slope > 100% or 45 degrees) you need to be extra careful in flight planning. The spatial resolution of the elevation data (SRTM database) is 30m and the steeper the terrain, the higher the uncertainty of the data. Moreover, overshoots of WingtraOne in turns (especially in high winds) can lead to substantial risk in steep terrain. If you can afford, please consider using higher GSD (fly higher above ground) than normally. Furthermore, it is recommended to set the ground clearance parameter to a higher value to account for the additional uncertainty. Manually check points along the flight plan that come close to ground, rocks, or other obstacles.