Canadian Forest Service Publications

Exploring the impact of airtanker drops on in-stand temperature and relative humidity. Melanie Wheatley, Anne Cotton-Gagnon, Jonathan Boucher, B. Mike Wotton, Colin B. McFayden, Natasha Jurko, Jason Robinson

Year: 2023

Issued by: Great Lakes Forestry Centre

Catalog ID: 41014

Language: English

Availability: PDF (request by e-mail)

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Plain Language Summary

Airtankers are used to suppress wildland fires in the Canadian boreal, specifically skimmer or tanking aircraft that drop water. Aside from the effect of water to cool a burning area, it has been suggested airtanker drops also create a micro-climate relative humidity bubble. We tested four different fixed-wing and one rotary-wing airtanker to investigate (1) if an airtanker creates a relative humidity bubble, (2) how long this bubble lasts and (3) if the bubble would change fire behaviour by itself. We also explored differences between water, and water additives (foam and gel) drops. We found that there is a relative humidity bubble created after airtanker drops, however, it is unlikely the bubble itself would have a meaningful change to fire behaviour. It is far more likely that wetting the fuel directly is the most impactful effect of an airtanker drop.