There is a high time-limit requirement for emergency of wildfire near transmission lines. Helicopters have advantages in extinguishing wildfire near transmission lines. Aiming at the problems of large amount of drifting and uneven fire extinguishing by helicopter drop extinguishing agent

we proposed a scheme of full-scale and full-process helicopter extinguishing agent drop tests for wildfire. Drop experiments at different altitudes and different flying speeds were carried out. The distribution of fire extinguishing agent depth was measured

and the distribution pattern of extinguishing agent was obtained. According to the efficiency of extinguishing agent

the high-efficiency

effective

and ineffective spraying areas were obtained. The drift amount and utilization rate of helicopter fire extinguishing water agent were calculated

which could provide a theoretical foundation for the compilation of helicopter fire extinguishing strategy on the transmission line mountain fire site. It is found that the coverage area of the fire extinguishing agent will increase with the increase of flight speed and flight altitude. The maximum depth of fire extinguishing liquid is 1.6 mm. When using pure water for fire extinguishing

the maximum utilization rate of fire extinguishing agent is only 1.4%. When high-efficiency fire extinguishing agent is used to extinguish a fire

the utilization rate of the fire extinguishing agent can reach 30%～70%. Based on the test conclusions of this paper

a high-efficiency fire suppression strategy for firefighting of the wildfire is formulated. The application of wildfire near transmission lines by helicopter spraying system has been carried out. Furthermore

the firefighting of wildfire near 500 kV Wumin during the Qingming period in 2019 is taken as an example

and the results show that when the test data and conclusions are adopted

the wildfire with an area of 600 square meters is quickly extinguished in 20 minutes. The applicability and advantages to guide the on-site hill fire suppression of the rules for wildfire drop can be verified.