Something

CREATE TABLE Planemodel 
( 
	make      VARCHAR(10),
	model     VARCHAR(10),   
	capacity  INTEGER NOT NULL,
	range     INTEGER NOT NULL,
	weight    INTEGER NOT NULL,
	CONSTRAINT PlaneModel_PK PRIMARY KEY (make,model)
);

CREATE TABLE Substitute
(
	make      VARCHAR(10) NOT NULL,
        model     VARCHAR(10) NOT NULL,
        substituteMake VARCHAR(10) NOT NULL,
        substituteModel VARCHAR(10) NOT NULL,
        CONSTRAINT Substitute_FK1 FOREIGN KEY (make,model)  REFERENCES Planemodel,
        CONSTRAINT Substitute_FK2 FOREIGN KEY (substituteMake,substituteModel)  REFERENCES Planemodel
);