Civil aviation is always the silver bullet target of the terrorist due to countless favorable reason for them. After the World Trade Center attack on September 11, 2001, world countries impose stringent security norms to keep civil aviation safe and to avoid another airborne catastrophe. Theamplified security measures eroded the probability of a conventional terrorist attack, and consequently, the terrorist organizations are being compelled to seek innovative ways to plan an attack. This led to the origin of an alternative form of terrorism, perpetrated by employees working inside the civil aviation or the so called insider threat. This paper provides valuable insights about the insider threat, why they are so challenging, types of insiders, their motivation, an analysis of the possibility of them being identified at the pre-attack stage, and other mitigation processes that could be utilized to ensure the safety of civil aviation