Hello Dlimos,
I tried what you advised me to do and this is perfectly working !! Thank you a lot !
To any people that might face this problem, this is the js function I used :
function buildPoint(point,angle, nav_long){
var coord = esri.geometry.lngLatToXY(point.getLongitude(),point.getLatitude(),true);
var ox = coord[0]+ Math.cos(angle/180*Math.PI)*nav_long;
var oy = coord[1] + Math.sin(angle/180*Math.PI)*nav_long;
var newPoint = new esri.geometry.Point(esri.geometry.xyToLngLat(ox,oy),new esri.SpatialReference({
wkid:4326
}));
return newPoint;
}
OlivierL