from my understanding Flight-Equipment-Seat is read-only data that some staff of FBN maintains which is beyond the scope of this assignment. Further you will have some "SearchManager" (POJO-DAO) that hides the rather complex algorithm of doing the actual search. I also assume that this searching algorithm is on a more detailed level and not part of the architecture, therefore I just assume a complex searching transportation algorithm but will NOT show the algorithm itself (e.g. in the sequence diagaram). Is that an assumption I can make? However, I am not sure if the search uses Flight or Segment? If it searches on the Segment then Segment will also be read-only but I am not confident if that is the case.
Also, what class would use the SearchManager? Right now I am thinking about the Itinerary using the SearchManager. Would you show the SearchManager in the class diagram or only in the sequence and component diagrams?