Method for graphic representation of the relative position of the sky and the earth in an onboard display system for aircraft

The general field of the invention is that of the methods for graphic representation of the relative position of the sky and of the earth in an onboard display system for aircraft, said graphic representation being displayed on a display screen comprising piloting and navigation information superimposed on a three-dimensional synthetic representation of the outside landscape. Said graphic representation is displayed only when the attitude of the aircraft is unusual, an unusual attitude corresponding to a roll value or to a pitch value located outside of a first range of nominal values. It comprises two disc segments of identical form, that are opaque and of different colour, situated symmetrically on a circle concentric to that bearing the roll scale, the straight-line segments of the two disc segments being parallel to the line representing the zero longitudinal trim indicator, the rotation of the two disc segments being slaved to the rotation of said zero longitudinal trim indicator.