Fighting fire in the heat of the day: an analysis of operational and environmental conditions of use for large airtankers in United States fire suppression

Large airtanker use is widespread in wildfire suppression in the United States. The current approach to nationally dispatching the fleet of federal contract airtankers relies on filling requests for airtankers to achieve suppression objectives identified by fire managers at the incident level. In general, demand is met if resources are available, and the dispatch model assumes that this use is both necessary and effective. However, proof of effectiveness under specific conditions of use in complex environments has not been empirically established. We geospatially intersected historical drop data from the federal contract large airtanker fleet with operational and environmental factors to provide a post hoc assessment of conditions of use for the 2010–12 fire seasons in the conterminous United States. Our findings confirm previous results demonstrating extensive use in extended attack. Additionally, we show that use is generally within guidelines for operational application (aircraft speed and height above ground level) and often outside of environmental guidelines suggestive of conditions conducive for most effective use, including drop timing with respect to response phase (initial attack v. extended attack), terrain, fuels and time of day. Finally, our results suggest that proximity to human populations plays a role in whether airtankers are dispatched, suggesting that prioritisation of community protection is an important consideration. This work advances efforts to understand the economic effectiveness of aviation use in federal fire suppression.