def __init__(self, parent=None):
        super(FuelPlanner, self).__init__(parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.msgBox = QtWidgets.QMessageBox()
        #Pesos
        self.MRW = 106000
        self.MTOW = 105000
        self.MZFW = 87000
        self.SOW = 61252
        self.MLW = 95300
        #inicializando aeronave vacia
        self.ZFW = 61252
        self.TOW = 61252
        #inicializando combustible
        self.combustible_minimo_vuelo = 8040
        self.combustible_maximo = 24649
        self.combustible_reserva_final = 4000

        self.tiempo_reserva_final = timedelta(minutes=45)
        self.tiempo_extra = timedelta()

        self.ui.timeEdit_reserva_final.setTime(QtCore.QTime(0, 45))
        self.ui.lineEdit_num_app.setText(
            "650")  #por defecto una sola app instrumental
        self.ui.comboBox_num_app.currentIndexChanged.connect(
            self.calcular_combustible_apps)
        self.ui.spinBox_extra.valueChanged.connect(self.calcular_tiempo_extra)
        self.ui.pushButton.clicked.connect(self.calcular)