Method contributing to making safe a synthetic graphical representation of the view outside an aircraft, said aircraft comprising at least one visualisation viewing means (2,6) on which it is possible to display on the one hand an at least partial view in perspective of the environment of said aircraft and on the other hand piloting symbology of said aircraft, a roll axis (X 10) extending from the rear of said aircraft to the front of the aircraft, a yaw axis (Z 10) extending upwards perpendicularly to said roll axis (X 10) and a pitch axis (Y 10) extending from right to left perpendicularly to said roll axis (X 10) and yaw axis (Z 10), forming a local reference frame (X 10, Y 10, Z 10) tied to said aircraft, characterised in that, - at least the heading and the attitude of said aircraft and a reference point (Pr) of said aircraft are determined, - at least ono shock point (D 1, D 2, D 3) situated in said environment of said aircraft is defined, each check point (P 1,P 2,P 3) forming with said reference point (Pr) a first straight line (D P1,D P2,D P3), the position of each first straight line (D P1, D P2, D P3) being known in said local reference frame (X 10, Y 10, Z 10) tied to said aircraft, - the display coordinates (a 1,b 1), (a 2,b 2), (a 3,b 3) of each check point (P 1, P 2, P 3) on said visualisation viewing means (2,6) are calculated by a first display function (F 1), - a second straight line (D S1, D S2, D S3) for each check point (P 1,P 2,P 3) is calculated by the inverse ((F 2) -1) of a second display function (F 2) and from said display coordinates (a 1,b 1) (a 2, b 2), (a 3, b 3), each second straight line (D S1,D S2,D S3) passing through said reference point (Pr) of said aircraft, said first display function (F 1) and said second display function (F 2) being distinct, - each first straight line (D P1,D P2, D P3) and each second straight line (D S1, D S2, D S3) corresponding to a same check point (P 1,P 2,P 3) are compared, - it is defined that said at least partial view in perspective of the environment of said aircraft is trustworthy if each first straight line (D P1, D P2, D P3) and each second straight line (D S1, D S2, D S3) corresponding to a same check point (P 1,P 2,P 3) have an angular difference less than or equal to a predetermined margin. - at least the heading and the attitude of said aircraft and a reference point (Pr) of said aircraft are determined, - at least ono shock point (D 1, D 2, D 3) situated in said environment of said aircraft is defined, each check point (P 1,P 2,P 3) forming with said reference point (Pr) a first straight line (D P1,D P2,D P3), the position of each first straight line (D P1, D P2, D P3) being known in said local reference frame (X 10, Y 10, Z 10) tied to said aircraft, - the display coordinates (a 1,b 1), (a 2,b 2), (a 3,b 3) of each check point (P 1, P 2, P 3) on said visualisation viewing means (2,6) are calculated by a first display function (F 1), - a second straight line (D S1, D S2, D S3) for each check point (P 1,P 2,P 3) is calculated by the inverse ((F 2) -1) of a second display function (F 2) and from said display coordinates (a 1,b 1) (a 2, b 2), (a 3, b 3), each second straight line (D S1,D S2,D S3) passing through said reference point (Pr) of said aircraft, said first display function (F 1) and said second display function (F 2) being distinct, - each first straight line (D P1,D P2, D P3) and each second straight line (D S1, D S2, D S3) corresponding to a same check point (P 1,P 2,P 3) are compared, - it is defined that said at least partial view in perspective of the environment of said aircraft is trustworthy if each first straight line (D P1, D P2, D P3) and each second straight line (D S1, D S2, D S3) corresponding to a same check point (P 1,P 2,P 3) have an angular difference less than or equal to a predetermined margin.