The aviation industry is the center of gravity for tourism-dependent countries seeking to uplift their economic activities. The COVID-19 pandemic in the early part of 2020 threatened people and the air industry to the maximum extent. This paper investigated the sustainable air travel behavior of passengers under the risk knowledge path. The mediating role of risk perception, i.e., physical risk, psychological risk, and service quality, was also tested for the risk knowledge-air travel behavior association. We surveyed 339 travelers at six airports in Thailand from January to June 2021 to record their responses. We applied covariance–variance-based structural equation modeling (CB-SEM), and the study results revealed a direct effect of risk knowledge with an indirect impact via risk perception paths on air travel behavior. This paper highlights knowledge as a remedial response to the perceptual makeup of air services sustainability. The study has solid managerial implications for aviation management in the design of ideal pathways for retaining air services during the current public emergency of COVID-19.