 Decalage is said to be positive when the upper wing has a higher angle of incidence than the lower wing, and negative when the lower wing's incidence is greater than that of the upper wing.Positive decalage results in greater lift from the upper wing than the lower wing, the difference increasing with the amount of decalage.In a survey of representative biplanes, real-life design decalage is typically zero, with both wings having equal incidence.