Comprehension of customer complaints is regarded as an essential factor for firms to recognize the service problem to recover the service. This study objective is to investigate the relationship between load factor, service failures, and customer complaints in the US airline industry by analyzing the panel data. In particular, the lagged effect and nonlinear relationship between load factor, service failure and customer complaints. The results reveal that the load factor has a positive effect on service failure. Furthermore, the load factor and the indicators of service failure which are airline cancellation, delay, and mishandled baggage have a lagged effect on customer complaints. Finally, the airline cancellations, delay, and load factor show the non-linear relationship with customer complaints in the airline industry. Contributions of this paper are twofold. First, the effects of load factor and service failures on customer complaints were able to be detected accurately, by using longitudinal data. Secondly, empirical results provide implications to the existing body of knowledge on service failure and service quality, and proposed findings can provide implications for airline management.