Final answer:
Without specific details of the FAC coding system, it is not possible to determine which flights FAC 5421 includes; it could encompass bomber, fighter, or special mission flights.
Step-by-step explanation:
The Functional Account Code (FAC) 5421 is not explicitly detailed in the provided reference material. Consequently, without additional information regarding the specific coding system or context in which FAC 5421 is used, it is not possible to accurately determine which flight(s) it includes. Functional account codes are typically used for classifying expenses and budgets within an organization, which could relate to various operational aspects such as flights in the military or airforce context. However, based on the provided context that mentions a B-66 bomber and F-105 fighter jets during a mission, one can hypothesize that FAC 5421 could potentially encompass a range of military aircraft flights such as bomber flights, fighter flights, and possibly special mission flights. Without specific details on the FAC coding system, a clear answer cannot be given.