section 20 a of nacelle 20 when the doors 24 26 are in their stowed position as in fig1 the engine is in a thrust reversal mode in fig2 this mode is generally used immediately after landing an aircraft on a runway the doors 24 26 are pivoted to that position simultaneously using actuators not shown the arrows a 2 a 3 in fig2 indicate the main flow path of the efflux coming out of the engine when operated during the thrust reversal as can be seen a large portion of the gases coming out of the engine are deviated substantially toward the front the gases exit the doors 24 26 in the vicinity of their leading edges 24 b 26 b these edges are located at the front of the doors 24 26 and are referred to as u201c leading u201d edges with reference to the travel path of the aircraft the deviation of the gases creates a resulting horizontal retarding force opposing the forward movement of the aircraft increasing the output thrust generated by the engine creates an increased aerodynamic decelerating force thus more braking fig2 and 3 show that the trailing edge 24 a of the upper door 24 is pivoted behind the trailing edge 26 a of the lower door 26 when the doors 24 26 are deployed this can be achieved for example from an asymmetrical positioning of the door pivots with reference to the horizontal center plane of the jet pipe 30 such.