Method for merging monitoring indicators of a device (3,4), measurement sensors (101,102,103) being positioned on said device (3,4) and/or close to said device (3,4), measurements of at least one of said sensors (101,102,103) making it possible to determine at least one monitoring indicator Ind i, each monitoring indicator Ind i being associated with a detection threshold Sd i, during which - during a preliminary step, said monitoring indicators Ind i of said device (3,4) are distributed in at least one group of indicators G, an algorithm g being applied to said monitoring indicators Ind i of a group of indicators G in order to determine a characteristic operating point Pf of said device (3,4) for said group of indicators G, - during a training step, there are determined a representative model Mr of the healthy state of said device (3,4), a belonging function f of a characteristic operating point Pf of said device (3,4) to said representative model Mr of the healthy state of said device (3,4) for said group of indicators G, and also an alarm threshold Sa associated with said belonging function f based on training operating points, characterised in that - during a step of taking account of the detection thresholds Sd i, a transformation T of said belonging function f is determined so as to take into account on the one hand said alarm threshold Sa of said representative model Mr and on the other hand said detection thresholds Sd i of said monitoring indicators Ind i of said group G, - during a monitoring step, o said monitoring indicators Ind i of a group of indicators G are determined, o said merged indicator HI is determined by applying said transformation T to said monitoring indicators Ind i of a group of indicators G, o said merged indicator HI is compared with said alarm threshold Sa and o an operating state of said device (3,4) is deduced therefrom. - during a preliminary step, said monitoring indicators Ind i of said device (3,4) are distributed in at least one group of indicators G, an algorithm g being applied to said monitoring indicators Ind i of a group of indicators G in order to determine a characteristic operating point Pf of said device (3,4) for said group of indicators G, - during a training step, there are determined a representative model Mr of the healthy state of said device (3,4), a belonging function f of a characteristic operating point Pf of said device (3,4) to said representative model Mr of the healthy state of said device (3,4) for said group of indicators G, and also an alarm threshold Sa associated with said belonging function f based on training operating points, characterised in that - during a step of taking account of the detection thresholds Sd i, a transformation T of said belonging function f is determined so as to take into account on the one hand said alarm threshold Sa of said representative model Mr and on the other hand said detection thresholds Sd i of said monitoring indicators Ind i of said group G, - during a monitoring step, o said monitoring indicators Ind i of a group of indicators G are determined, o said merged indicator HI is determined by applying said transformation T to said monitoring indicators Ind i of a group of indicators G, o said merged indicator HI is compared with said alarm threshold Sa and o an operating state of said device (3,4) is deduced therefrom. o said monitoring indicators Ind i of a group of indicators G are determined, o said merged indicator HI is determined by applying said transformation T to said monitoring indicators Ind i of a group of indicators G, o said merged indicator HI is compared with said alarm threshold Sa and o an operating state of said device (3,4) is deduced therefrom.