Reach isn’t the same as delivery: a national directory for aerial firefighting reload water

Evaluating and pre-computing a map of every known water body in the U.S. shows where aerial firefighting aircraft can actually reload

Aerial firefighting coverage is usually measured by reach: whether an aircraft can get to a fire in time. That matters, but it is only part of it. A helicopter or a scooper does not make a single drop and stop. It drops, flies to water, reloads, and drops again, and how much it can put on a fire depends heavily on how close the nearest usable water is. Two of the same aircraft can deliver very different amounts, simply because one has a usable reload point closer than the other.

There has not been an open, national picture of which water an aircraft can actually reload from. This working paper builds one.

As one of multiple projects looking at a bigger question of whether we have enough aircraft in the first place and the best places to be positioning them, our Labs team used their experience in data science and machine learning to create a working paper that describes how a supporting geospatial dataset could be modelled.

We wrote a program that takes the United States Geological Survey’s national map of surface water, about 5.7 million water bodies, and measures the shape of each one, its size, length, and width, to work out whether it could serve as a reload point for each aircraft class: open water a helicopter can dip into, and a long, wide, clear run a fixed-wing scooper needs. The output is a national layer that records each water body’s dimensions and whether it could work for helicopter, Fire Boss, or CL-415 aircraft. About 3.6 million bodies work for helicopters and about 57,000 for the fixed-wing scoopers, and the scooper-capable ones are unevenly spread, concentrated across the northern states and the reservoir-heavy West and sparse through drier country.

The precomputed locations look only at the shape of the water as it is mapped. It does not assess depth, current water level, obstacles, access, or whether a body is approved for use. A positive result is a candidate to check, not an operational green light.

What it enables is coverage measured by delivery rather than reach alone: how much can actually be put on an incident, where reload distance limits response regardless of flight time, and where to base and pre-position rotary and scooper aircraft. It feeds directly into standards-of-cover analysis.

The paper is built entirely on public data, and we are sharing it openly. It is the first of several pieces from TracPlus Labs on measuring aerial firefighting capability and coverage.

Read the full working paper here.

Alongside the paper, we’re also sharing the geospatial output itself, the full national dataset behind this screen, in GeoParquet format. It’s a working output rather than a polished tool, shared for anyone who wants to see what the data looks like up close. Learn More.