VLAT

A VLAT is a fixed-wing aircraft equipped to carry and drop large volumes of water or fire retardant on wildfires. These are the largest machines in the aerial firefighting fleet, typically holding 3,000 to 10,000 U.S. gallons per load, compared to 400 to 800 gallons for conventional air tankers. They are used on uncontained wildfires where ground crews cannot safely operate and where access by road is impossible or delayed.

Most VLATs are conversions of retired military or cargo aircraft: the C-130 Hercules, the Boeing 747, and the Airbus A400M are common platforms. Some are large amphibious aircraft originally built for water bombing, such as the Canadair CL-415. The conversion involves installing tanks that can fill in minutes from ground reservoirs and systems to release the load precisely over the fire perimeter. Flight crews operate at low altitudes in poor visibility and near terrain hazards, often in hot, turbulent air.

Retardant drops happen on the flanks and head of a fire to slow its spread or create a defensible line for ground crews. Water drops are used on active hotspots. A single VLAT mission can cost thousands of dollars in fuel and crew time; availability is limited by aircraft age, maintenance cycles, and seasonal demand across regions and continents. During peak wildfire season in the Northern Hemisphere, demand often exceeds supply.

Hazards and constraints

VLATs operate in extreme conditions. Smoke obscures landmarks and runways. Downdraughts from terrain and convection from the fire itself create sudden wind shear. Retardant corrosion affects engine components and visibility from the cockpit. Residual fuel and slurry weight affect balance and fuel consumption. Loss of situational awareness, spatial disorientation, and controlled flight into terrain are primary accident modes.

The term emerged in the 1990s as air tanker fleets were classified by payload: large air tankers (LATs) carried 2,000 to 3,000 gallons; very large air tankers were the next tier up. The distinction remains useful for logistical and operational planning, though aircraft capability now varies widely regardless of label.