Method for controlling an economy operating mode for an aircraft, said aircraft being provided with at least one rotor (2,3) and at least two heat engines rotating said at least one rotor (2,3), said aircraft having a controller configured to control said heat engines in at least said economy operating mode wherein at least one active engine from among said heat engines supplies non-zero mechanical power to said at least one rotor (2,3) and at least one passive engine from among said other heat engines does not supply mechanical power to said at least one rotor (2,3), said method comprising the following steps: - measuring operating parameters of said aircraft by means of sensors, - using a calculator to compare said operating parameters of said aircraft with safety limitations and functional limitations relating to said economy operating mode, said safety limitations having a direct effect on the safety of the flight of said aircraft, said functional limitations having an effect on the operation of said aircraft and/or on the effectiveness of said economy operating mode, - if said aircraft is in said economy operating mode and at least one of said functional limitations is not being respected and said safety limitations are being respected, issuing an alert indicating that said functional limitations of said economy operating mode have been exceeded, and - if said aircraft is in said economy operating mode and at least one of said safety limitations is not being respected, automatically disengaging said economy operating mode, said automatic disengagement comprising activation of said at least one passive engine by means of said controller, characterised in that said method comprises normal starting and accelerated starting of said at least one passive engine in said economy operating mode, said normal starting comprising a first acceleration of said at least one passive engine for a first time period, until it supplies non-zero mechanical power to said at least one rotor, said accelerated starting comprising a second acceleration of said at least one passive engine for a second time period, until it supplies non-zero mechanical power to said at least one rotor (2,3), said second time period being shorter than said first time period, said normal starting taking place following the issuing of an alert indicating that said functional limitations of said economy operating mode have been exceeded and if a pilot of said aircraft authorises the disengagement of said economy operating mode by means of an interface, said accelerated starting being carried out upon said activation. said method comprising the following steps: - measuring operating parameters of said aircraft by means of sensors, - using a calculator to compare said operating parameters of said aircraft with safety limitations and functional limitations relating to said economy operating mode, said safety limitations having a direct effect on the safety of the flight of said aircraft, said functional limitations having an effect on the operation of said aircraft and/or on the effectiveness of said economy operating mode, - if said aircraft is in said economy operating mode and at least one of said functional limitations is not being respected and said safety limitations are being respected, issuing an alert indicating that said functional limitations of said economy operating mode have been exceeded, and - if said aircraft is in said economy operating mode and at least one of said safety limitations is not being respected, automatically disengaging said economy operating mode, said automatic disengagement comprising activation of said at least one passive engine by means of said controller, - measuring operating parameters of said aircraft by means of sensors, - using a calculator to compare said operating parameters of said aircraft with safety limitations and functional limitations relating to said economy operating mode, said safety limitations having a direct effect on the safety of the flight of said aircraft, said functional limitations having an effect on the operation of said aircraft and/or on the effectiveness of said economy operating mode, - if said aircraft is in said economy operating mode and at least one of said functional limitations is not being respected and said safety limitations are being respected, issuing an alert indicating that said functional limitations of said economy operating mode have been exceeded, and - if said aircraft is in said economy operating mode and at least one of said safety limitations is not being respected, automatically disengaging said economy operating mode, said automatic disengagement comprising activation of said at least one passive engine by means of said controller, characterised in that said method comprises normal starting and accelerated starting of said at least one passive engine in said economy operating mode, said normal starting comprising a first acceleration of said at least one passive engine for a first time period, until it supplies non-zero mechanical power to said at least one rotor, said accelerated starting comprising a second acceleration of said at least one passive engine for a second time period, until it supplies non-zero mechanical power to said at least one rotor (2,3), said second time period being shorter than said first time period, said normal starting taking place following the issuing of an alert indicating that said functional limitations of said economy operating mode have been exceeded and if a pilot of said aircraft authorises the disengagement of said economy operating mode by means of an interface, said accelerated starting being carried out upon said activation.