PLANE_TYPE(Model, Capacity, Weight)
        PK: Model

AIRPLANE(Reg, Plane_Model, Hangar_No)
        PK: Reg,
        FK: Plane_Model that references PLANE_TYPE.Model
               Hangar_NO that references HANGAR.Number

HANGAR(Number, Capacity, Location)
        PK: Number

OWNER(OwnerID )
        PK: OwnerID

CORPORATION(Name, Address, Phone, OwnerID)
        PK: Name
        FK: OwnerID that references OWNER.OwnerID

PERSON(SSN, Address, Phone, Name, OwnerID)
        PK: SSN
        FK: OwnerID that references OWNER.OwnerID

PILOT(SSN, Lic_Num, Restr)
        PK: SSN
        FK SSN that references PERSON.SSN

EMPLOYEE(SSN, Salary, Shift)
        PK: SSN
        FK: SSN that references PERSON.SSN

SERVICE(AirplaneReg, Date, Workcode, Hours)
        PK: AirplaneReg, Date, Wrokcode
        FK: AirplaneReg that references AIRPLANE.Reg

FLIES(Model, SSN)
        PK: Model, SSN
        FK: Model that references PLANE_TYPE.Model
               SSN that references PILOT.SSN

WORK_ON(SSN, PlaneModel)
        PK: SSN, PlaneModel
        FK: SSN that references EMPLOYEE.SSN
               PlaneModel that references PLANE_TYPE.Model

MAINTAIN(SSN, AirplaneReg, Date, Wrokcode)
        PK: SSN, AirplaneReg, Date, Wrokcode
        FK: SSN that references EMPLOYEE.SSN
               AirplaneReg, Date, Wrokcode that reference SERVICE. AirplaneReg, SERVICE.Date, SERVICE.Wrokcode respectively.

OWNS(OwnerID, AirplaneReg, Pdate)
        PK: OwnerID, AirplaneReg
        FK: OwnerID that references OWNER.OwnerID
               AirplaneReg that reference AIRPLANE.Reg