Flight safety during the landing phase is crucial, and many environmental factors may undermine this process. Sun glare has been identified as an important environmental factor affecting operation performance, but the empirical evidence concerning its effects requires further exploration. This study investigates the effect of sun glare on flight landing performance based on real flight QAR data. Five landing performance indicators were extracted from the QAR data encompassing 1235 flights at an east-west runway airport during clear weather conditions. We examined whether landing performance can be undermined when sun glare is more likely to happen, specifically during westward landing in the late afternoon and eastward landing in the early morning. The general linear model analysis findings reveal a marginally significant interaction effect between runway direction and time period on touchdown distance. Notably, in the morning, eastward landings exhibited longer touchdown distances compared to westward landings, while during the late afternoon, the opposite trend was observed with westward touchdown distances being longer. This study offers a novel perspective on how environmental factors can influence flight performance. The findings hold promise in devising strategies to mitigate the adverse effects of sun glare on flight operation performance, thereby enhancing overall flight safety standards.