@startuml

class AirplaneModel {
    Int ModelId
}

class Airplane {
    Int AirPlaneId
}

class Acquisition {
    Int AcquisitionId
    Float NegotiatedPice
    String Options
    DateTime DeliveryDate
}

class Contract {
    Int ContractId
    String Text
}

class Employee {
    Int EmployeeId
}

class Airline {
    String Name
}


AirplaneModel "1" -- "0..*" Airplane
Airplane "0..1" -- "0..1" Acquisition : part of
Acquisition "0..*" -- "1" Contract : part of
Contract "0..*" -- "1" Airline
Contract "0..*" -- "1" Employee
Airline "0..1" -- "0..*" Airline

@enduml