A method of detecting and avoiding conflict along a current route of an unmanned aerial vehicle , the method comprising: accessing a trajectory of the unmanned aerial vehicle on the current route of the unmanned aerial vehicle, and a predicted trajectory of a nearby moving object; detecting a conflict between the unmanned aerial vehicle and the nearby moving object from a comparison of the unmanned aerial vehicle and the nearby moving object on respectively the trajectory of the unmanned aerial vehicle, and the predicted trajectory of the nearby moving object; determining a plurality of alternate routes for the unmanned aerial vehicle, each alternate route including an alternate route segment offset from the current route by a fixed offset, and a transition segment from the current route to the alternate route segment; evaluating routes, including the plurality of alternate routes, according to a cost metric that depends on a time or distance to a point of approach between the nearby moving object and the unmanned aerial vehicle, and a distance from the current route, wherein the cost metric is defined such that the current route is the highest ranked one of the routes when the conflict is no longer detected for the unmanned aerial vehicle on the current route and higher ranked routes are those with a longer time or distance to the point of approach, and/or closest to the current route ; selecting one of the alternate routes from the plurality of alternate routes for use in at least one of guidance, navigation or control of the unmanned aerial vehicle to avoid the conflict, wherein the selected alternate route is a higher ranked route; causing the unmanned aerial vehicle to travel the selected alternate route to avoid the conflict; and causing the unmanned aerial vehicle to return to the current route during travel of the unmanned aerial vehicle on the alternate route. accessing a trajectory of the unmanned aerial vehicle on the current route of the unmanned aerial vehicle, and a predicted trajectory of a nearby moving object; detecting a conflict between the unmanned aerial vehicle and the nearby moving object from a comparison of the unmanned aerial vehicle and the nearby moving object on respectively the trajectory of the unmanned aerial vehicle, and the predicted trajectory of the nearby moving object; determining a plurality of alternate routes for the unmanned aerial vehicle, each alternate route including an alternate route segment offset from the current route by a fixed offset, and a transition segment from the current route to the alternate route segment; evaluating routes, including the plurality of alternate routes, according to a cost metric that depends on a time or distance to a point of approach between the nearby moving object and the unmanned aerial vehicle, and a distance from the current route, wherein the cost metric is defined such that the current route is the highest ranked one of the routes when the conflict is no longer detected for the unmanned aerial vehicle on the current route and higher ranked routes are those with a longer time or distance to the point of approach, and/or closest to the current route ; selecting one of the alternate routes from the plurality of alternate routes for use in at least one of guidance, navigation or control of the unmanned aerial vehicle to avoid the conflict, wherein the selected alternate route is a higher ranked route; causing the unmanned aerial vehicle to travel the selected alternate route to avoid the conflict; and causing the unmanned aerial vehicle to return to the current route during travel of the unmanned aerial vehicle on the alternate route. <EOS>