说明：  一、民航管理系统设计： 民航系统功能：能给客户提供订票、退票的功能，还能浏览航班航线信息（如航班号、航线、飞行时间及成员订额）和查询航班信息； 民航系统的具体实现如下形式： 1.系统以菜单方式工作 2.航班信息录入功能(航班信息用文件保存)－－输入 3.航班信息浏览功能－－输出 4.查询航线（按航班号查询） 5.承办订票和退票业务
(a CAD management system design : CAD system function : to provide their customers with booking, a refund of the function, flight routes can browse information (such as flight number, route, time of flight and members of the amount set), and check their flight information; the CAD system is a concrete realization of the following forms : 1. the menu system to work two ways. flight information into functional (flight information in document preservation)-- input 3. flights information browsing-- output 4. inquiries route (flights inquiry) 5. contractors booking business and Refund)