Aircraft having a fuselage and provided with an airbag system for the aircraft of an auto-adaptive type comprising a first airbag assembly carried by the fuselage and adapted to extend, when inflated following its activation, from a lower side of the fuselage of the aircraft and at least a second airbag assembly carried by the fuselage and adapted to extend, when inflated following its activation, from the lower side of the fuselage of the aircraft, the first and the second airbag assemblies (3, 5) being spaced from one another along the fuselage of the aircraft, wherein each first and second airbag assembly (3, 5) is configured to be partially or completely activated to alternatively carry out a first arrangement in which the airbag body extends by a first length from the fuselage of the aircraft and a second arrangement in which the airbag body extends by a second length greater than the first length from the fuselage of the aircraft; the airbag system is provided with an electronic control unit adapted to detect flight parameters of said aircraft prior to the impact so as to carry out the partial/total activation of each first/second airbag assembly (3, 5) and reduce the impact loads, wherein the first airbag assembly and the second airbag assembly are arranged spaced from each other along the fuselage and are adapted to reduce the loads, resulting from an impact in water of the fuselage of the aircraft; said electronic control unit being adapted to detect the predicted pitch angle upon impact on the water surface and being configured to compare the detected pitch angle with a target pitch angle predicted by the flight manuals to reduce impact loads: said electronic control unit being adapted to control, based on the results of the comparison, the partial or total activation of said first and said second airbag assemblies (3, 5); characterised in that each first and second airbag assembly (3, 5) comprises a first inflatable casing configured to assume, in use, a toroidal shape around an axis and a second inflatable casing carried by the first casing and configured to assume, in use, a cylindrical shape around the axis with an elongated portion extending axially through the central opening of the first toroidal inflatable casing; further characterised in that the first inflatable casing is connected to at least one first gas source and the free end of the elongated portion is connected to at least a second gas source; both of the gas sources (20, 22) are activatable by said electronic control unit; when only the first gas source is activated the partial activation of said first airbag assembly is carried out with the deployment of only the first casing and when both of the gas sources (20, 22) are activated the total activation of said first airbag assembly is carried out with the deployment of both casings (12, 14). wherein each first and second airbag assembly (3, 5) is configured to be partially or completely activated to alternatively carry out a first arrangement in which the airbag body extends by a first length from the fuselage of the aircraft and a second arrangement in which the airbag body extends by a second length greater than the first length from the fuselage of the aircraft; the airbag system is provided with an electronic control unit adapted to detect flight parameters of said aircraft prior to the impact so as to carry out the partial/total activation of each first/second airbag assembly (3, 5) and reduce the impact loads, wherein the first airbag assembly and the second airbag assembly are arranged spaced from each other along the fuselage and are adapted to reduce the loads, resulting from an impact in water of the fuselage of the aircraft; said electronic control unit being adapted to detect the predicted pitch angle upon impact on the water surface and being configured to compare the detected pitch angle with a target pitch angle predicted by the flight manuals to reduce impact loads: said electronic control unit being adapted to control, based on the results of the comparison, the partial or total activation of said first and said second airbag assemblies (3, 5); characterised in that each first and second airbag assembly (3, 5) comprises a first inflatable casing configured to assume, in use, a toroidal shape around an axis and a second inflatable casing carried by the first casing and configured to assume, in use, a cylindrical shape around the axis with an elongated portion extending axially through the central opening of the first toroidal inflatable casing; further characterised in that the first inflatable casing is connected to at least one first gas source and the free end of the elongated portion is connected to at least a second gas source; both of the gas sources (20, 22) are activatable by said electronic control unit; when only the first gas source is activated the partial activation of said first airbag assembly is carried out with the deployment of only the first casing and when both of the gas sources (20, 22) are activated the total activation of said first airbag assembly is carried out with the deployment of both casings (12, 14).