Patent ID: 8477048

Claim:
A method for preventing at least some alarms from being emitted by an anti-collision system ( 2 ) on board an airplane (AC) during an altitude change maneuver comprising an approach phase followed by a phase for capturing a set level (Zc), said anti-collision system ( 2 ) being able to detect at least one intrusive aircraft (AI) being located in the air environment of said airplane (AC), to calculate a theoretical collision time between said airplane (AC) and said intrusive aircraft (AI) and to emit first type alarms (TA) and second type alarms, when such a theoretical collision time is lower respectively than a first predetermined triggering threshold and a second predetermined triggering threshold, characterized in that, when said airplane (AC) is flying to said set level (Zc) with a vertical speed (Vz), the absolute value of which is at least equal to a first predetermined vertical speed threshold (Vz 1 ), the following steps are carried out for preventing a second type alarm from being emitted: the emission of a first type alarm (TA) is first detected; in the case where said first type detected alarm (TA) occurs when the height (h) separating said airplane (AC) from said set level (Zc) is at the most equal to a predefined height threshold (ho), the vertical speed (Vz) of said airplane (AC) is reduced so that the absolute value thereof is equal to said first vertical speed threshold (Vz 1 ), so as to maintain the theoretical collision time associated with a second type alarm above the second triggering threshold; and in the case where said first type detected alarm (TA) occurs when the height (h) separating said airplane (AC) from said set level (Zc) is strictly higher than said height threshold (ho): i) as long as the height (h) separating said airplane (AC) from said set level (Zc) remains strictly higher than said height threshold (ho), the vertical speed (Vz) of said airplane (AC) is reduced so that the absolute value thereof is equal to a second predetermined vertical speed threshold (Vz 2 ); and ii) then, when the height (h) separating said airplane (AC) of said set level (Zc) is at the most equal to said height threshold (ho), the vertical speed (Vz) of said airplane (AC) is limited so that the absolute value thereof is equal to said first vertical speed threshold (Vz 1 ), until said capture phase is initiated, so as to maintain the theoretical collision time associated with a second type alarm above the second triggering threshold.