Estimation of the economic impacts and operational limitations imposed on unmanned aerial systems by poor sky conditions

Cloudy skies reduce image quality obtained from unmanned aerial vehicles (UAV) due to variable lighting conditions imposed on the surface. This study provides a novel approach for identifying temporal windows of opportunity that show promise for avoiding such reductions. The total available hours for flight within a growing season were determined based on an hourly assessment of sky condition. In the study region, this represents total hours from 9 AM to 3 PM, March 1 through September 30. The most promising windows were early and late season, and early morning and late afternoon. Monthly windows were well aligned with crop decision making for emergence. An economic case study was conducted to determine the impact of sky condition on per hectare custom rate for agricultural applications of UAV. Both full-season and early-season-only operational scenarios were investigated. Use of UAV was financially favorable despite the frequent presence of poor sky conditions thought to reduce image quality (60% of total hours). A custom rate of < US$3.65 ha⁻¹ for three flights accommodated a range of acceptable returns on investment over a 3 year period. Poor sky conditions increased the average custom rate by at most US$0.89 ha⁻¹ in the early-season-only scenario and US$0.77 ha⁻¹ over the full season. These rates are competitive with manned aircraft for average fields in the study region (80 ha). Although the initial perception was that clouds would reduce the potential for UAV operations when high image quality is required, economic analyses did not support this preliminary assumption.