Add the four dropdown menus – a list of departure airports, arrival airports, number of passengers (1-4), and a date dropdown for the flight date. The date dropdown should only include dates that have existing flights. Don’t worry about restricting the contents of the airport dropdowns – you’d normally use JavaScript – so just allow the user to select any airport. See this SO post on formatting date in dropdown lists, this quickie SO post on selecting months/years and the Rails DateHelper API Docs for some help with creating Date selects.