Forest fire, Firefighting aircraft, Critical safety height, Stall speed, Critical angle of attack, Science (General), Q1-390, Social sciences (General), H1-99

Although firefighting aircrafts are effective for fighting forest fires, they are affected by a variety of risks related to forest fires during flight operations such as thermal radiation, temperature rise, decrease in air density, and changes in updraft aerodynamics. Quantifying these influences poses a significant challenge. Our research reveals that safety standards predominantly hinge on technical indicators like flight height, speed, and angle of attack, which makes it possible to quantify the above effects. A general method framework for analysing firefighting flight safety criteria was constructed in this study. Using relevant physical models, such as heat radiation, temperature, air density, and updraft in a forest fire environment, safety criteria with an analytical form were established. The corresponding safety constraints of each criterion were calculated quantitatively, and the most stringent constraint was determined based on multiple factors to obtain a comprehensive safety constraint boundary composed of the critical height, stall speed, and critical angle of attack. Finally, the effectiveness of the method is validated through a simulation case. The research results show that the constrained boundary calculation method proposed in this study can provide a scientific foundation for developing technical specifications for forest aviation safety and aviation fire task plan.