This thesis aims to analyze an incidental event concerning the De-Icing procedure of an Airbus A320-216 aircraft, which occurred at Munich International Airport (MUC), as a complex socio-technological system using the Functional Resonance Analisys Method (FRAM). This study aims to understand which steps of the standardized De-Icing procedure (Work As Imagined) are different from the actions actually performed (Work As Done) as they conceal an intrinsic variability which, when combined, led to the generation of an emergency and how the current procedures implemented at the airports managed by the Società Esercizi Aeroportuali di Milano (SEA) allow the containment of such variability, reducing the probability of an accident occurring.