An Assessment of Aerial Firefighting Response Times Between Agencies During the 2020 Fire Season in California

Rapid, well‑coordinated aerial response can be an effective way to limit wildfire growth during the initial‑response period. To date, most studies of wildland fire aviation effectiveness have relied on data from aircraft provided by the United States Forest Service, while other agencies aircraft have received less attention. This study leverages open ADS‑B data to reconstruct second‑by‑second aircraft movements for both the CAL FIRE and USFS aircraft during the 2020 California fire season, allowing a comparison between use of different agency aircraft for the first time. This study characterizes the two fleets activity and identifies how landscape, weather, and values‑at‑risk influence time to first aircraft arrival within the first 24 hours after ignition. ADS‑B flight tracks for USFS and CAL FIRE aircraft were matched to 7,214 wildfires; response time was calculated as the interval between ignition discovery and the first ADS‑B detection within 5 km. Cause‑specific cumulative‑incidence curves compared the probability that each agency arrived first, while Cox proportional‑hazards models, with stratification by diurnal period and protecting agency, quantified the effects of slope, fuel moisture, weather, distance to water, and human exposure metrics on dispatch timing. Aircraft responded to 1,476 fires. Hazard ratios indicated faster response times on wildfires under higher temperatures, and nearer populations, while wetter fuels and greener than average vegetation conditions delayed response. This study demonstrates the feasibility of real‑time, cross‑agency performance monitoring, informing resource allocation, and future integration of ADS‑B with existing federal tracking systems for a comprehensive aviation situational awareness framework.