The method in accordance with the invention is a method of providing a 3D emergency descent trajectory for aircraft comprising the steps of searching for at least one possible better trajectory allowing a secure continuation in relation to the relief and/or the surrounding conditions towards a homing point as soon as a situation requiring an unscheduled modification of the current trajectory occurs, wherein this trajectory is updated as a function of the alterations in the surrounding conditions, as a function of the information provided by the onboard sensors and/or outside information received.