Method and device for automatically controlling an emergency descent of an aircraft
View Patent ↗A method and device automatically engage an emergency descent function of an aircraft as a function of pressure variation measured in the cabin of the aircraft.
1. A method of automatic control of an emergency descent of an aircraft, according to which method, when an automatic emergency descent function is engaged, the following successive operations are carried out:
a) determining automatically a set of vertical directives, said directives comprising:
a target altitude which represents an altitude to be attained by the aircraft at the end of the emergency descent; and
a target speed which represents a speed that the aircraft must comply with during the emergency descent;
b) determining automatically a set of lateral directives, which represents a lateral maneuver to be carried out during the emergency descent; and
c) guiding the aircraft automatically so that it complies simultaneously with said set of vertical directives and said set of lateral directives until it attains said target altitude which it thereafter maintains, said automatic guidance possibly being interrupted by an action of a pilot of the aircraft,
according to which method, to automatically engage said emergency descent function, the following operations are carried out in an automatic manner:
α1) determining a variation in altitude of the cabin of the aircraft, which depends on a variation in the pressure measured inside the cabin;
β1) determining an engagement criterion which depends on said variation in altitude of the cabin;
γ1) comparing this engagement criterion with a predetermined threshold value; and
δ1) engaging said emergency descent function when said engagement criterion is above said threshold value, wherein:
in step δ1), said emergency descent function is engaged when said engagement criterion is above said threshold value for a predetermined duration, and in step a), the following operations are moreover carried out in an automatic manner:
in a step α2):
a variation in the pressure of the air in the cabin is monitored; and
the size of a hole in the structure of the aircraft, corresponding to structural damage, is estimated as a function of said variation in the pressure of the air in the cabin; and
in a step β2), said target speed is adapted to said estimated size of the hole in the structure of the aircraft.
2. The method as claimed in claim 1 ,
wherein said engagement criterion corresponds to said variation in altitude of the cabin.
3. The method as claimed in claim 1 ,
wherein:
in step α1), an altitude of the cabin of the aircraft, which depends on a pressure measured inside the cabin is moreover determined; and
in step β1), an engagement criterion is determined as a function at one and the same time of said variation in altitude of the cabin and of said altitude of the cabin.
4. The method as claimed in claim 3 ,
wherein in step β1), one of the following engagement criteria x1, x2 and x3 is calculated:
{
x
1
=
G
1
a
c
.
A
c
+
G
1
vac
.
Vac
x
2
=
[
(
G
2
a
c
.
A
c
)
2
+
(
G
2
vac
.
Vac
)
2
]
1
/
2
x
3
=
[
(
G
3
a
c
.
A
c
)
n
+
(
G
3
vac
.
Vac
)
n
]
1
/
n
for which:
Ac represents said altitude of the cabin;
Vac represents said variation in altitude of the cabin;
n is an integer greater than 2; and
G1ac, G2ac, G3ac, G1vac, G2vac and G3vac are predetermined gain values.
5. The method as claimed in claim 1 ,
wherein means are provided allowing a pilot to manually engage said emergency descent function.
6. A device for the automatic control of an emergency descent of an aircraft, said device comprising:
engagement means able to engage an automatic emergency descent function;
means for determining, automatically, a set of vertical directives comprising:
a target altitude which represents an altitude to be attained by the aircraft at the end of the emergency descent; and
a target speed which represents a speed that the aircraft must comply with during the emergency descent;
means for determining, automatically, a set of lateral directives, which represents a lateral maneuver to be carried out during the emergency descent;
means for automatically guiding the aircraft, upon engagement of an automatic emergency descent function, so that it complies simultaneously with said set of vertical directives and said set of lateral directives until it attains said target altitude which it thereafter maintains; and
means allowing a pilot of the aircraft to manually interrupt said automatic guidance,
said engagement means comprising, for automatically engaging said emergency descent function:
means for automatically determining a variation in altitude of the cabin of the aircraft, which depends on a variation in the pressure measured inside the cabin;
means for automatically determining an engagement criterion which depends on said variation in altitude of the cabin;
means for automatically comparing this engagement criterion with a predetermined threshold value; and
means for automatically ordering the engagement of said emergency descent function, when said engagement criterion is above said threshold value,
wherein said device comprises, moreover:
means for automatically monitoring a variation in the pressure of the air in the cabin;
means for automatically estimating the size of a hole in the structure of the aircraft, corresponding to structural damage, as a function of said variation in the pressure of the air in the cabin; and
means for automatically adapting the target speed to said estimated size of the hole in the structure of the aircraft.
7. An aircraft,
which comprises a device such as that specified under claim 6 .