Thermographic inspection is a widely used non-destructive inspection (NDI) technique for evaluating the integrity of aircraft structural composites. Its extensive use in structural assessment stems from its relative simplicity and its effectiveness in detecting a broad range of defect types. This chapter presents the fundamental principles, methodologies, and practical applications of thermographic inspection within the aviation industry. It also discusses common defects found in aircraft composite materials and includes a case study addressing the detection of missing and excessive plies, metal and polymer inclusions, and fiber discontinuities in glass-fiber composite laminates. The results underscore the effectiveness of thermographic inspection for assessing aircraft structural composites, demonstrating its essential role in maintaining the safety and reliability of aerospace materials.