Patent Grant
7038613
The present invention relates to a method and a device for determining at least one cue of vertical position of an aircraft during landing thereof.
It is known that numerous airports are equipped with a ground-based radionavigation system emitting signals allowing instrument precision landing of the ILS (“Instrument Landing System”) type of an aircraft, in particular of a civil transport plane, equipped with appropriate receivers.
Such a radionavigation system comprises ground stations that are situated at the strip verge and at least one specialized radioreceiver mounted aboard the aircraft, which provides horizontal and vertical guidance before and during landing by presenting the pilot with the lateral deviation with respect to an approach axis and the vertical deviation with respect to a descent plane. Said radionavigation system generally comprises, as ground stations:
Such a radionavigation system affords considerable and effective assistance with landing (through lateral guidance and vertical guidance), in particular through poor visibility (fog, etc.) or in the absence of visibility.
However, it may happen that such a radionavigation system is incomplete or at least partially faulty so that the pilot then no longer has access to all the information allowing completely assisted landing.
The present invention applies to the case where no “glide” beam (vertical guidance) is available, only a “loc” beam (lateral guidance) being detectable from the aircraft.
Such a case may occur in particular in the following situations:
When such a case occurs, the pilot must manage the vertical guidance without assistance. Such management requires a considerable workload and close attention on the part of the pilot, and this may sometimes increase the risk of errors and hence entail lesser flight safety than during an “ILS” type precision approach, for which, as indicated above, the pilot benefits in particular from assistance in respect of vertical guidance.
An object of the present invention is to remedy these drawbacks. It relates to a method of determining at least one cue of vertical position of an aircraft during landing thereof on a landing strip, in the presence only of a lateral alignment beam (that is to say of a “loc” beam) which is emitted from the ground and which gives an indication regarding the lateral alignment with respect to the approach axis, and hence in the absence of a detectable vertical guidance beam (“glide” beam).
For this purpose, according to the invention, said method is noteworthy in that:
Thus, by virtue of the invention, a cue of vertical position of the aircraft is obtained solely on the basis of a lateral alignment beam (“loc” beam), that is to say without using a vertical guidance beam (“glide” beam).
Advantageously, in step b), to determine said approach axis:
Furthermore, advantageously, in step c), the actual position of the aircraft is determined on the basis of values of longitude, of latitude and of altitude of the aircraft.
In a preferred embodiment, the value of altitude of the aircraft is obtained with the aid of at least one measurement carried out by at least one barometric probe.
In this case, in a first variant embodiment, the altitude value which is measured is corrected, as a function of the temperature on the ground.
Preferably, the altitude value Am measured is corrected with the aid of the following expression, to obtain a corrected altitude value Ac:
Ac=(Am−Ap).(T1/T2)+Ap
in which:
Ap represents the altitude of the landing strip;
T1 is the temperature on the ground; and
T2 is a predetermined temperature value.
Advantageously, the altitude value is corrected only if the temperature on the ground is less than a predetermined temperature value.
In a second variant embodiment (which may be combined with said first variant embodiment described hereinabove, to provide the altitude value Am used in the altitude correction formula corresponding to said first variant), the altitude value measured is corrected if necessary in such a way as to obtain a corrected altitude value QNH which is referenced with respect to the level of the sea.
In this second variant, firstly, when the measured altitude value QFE is referenced with respect to the landing strip, it is corrected, with the aid of the following expression, to obtain the corrected altitude value QNH:
QNH=QFE+Ap,
in which Ap represents the altitude of the landing strip.
Furthermore, secondly, when the measured altitude value is a standard altitude STD, it is corrected, with the aid of the following expression, to obtain the corrected altitude value QNH:
QNH=STD+Δ with Δ=QNHp−β,
QNHp being a value dependent on the atmospheric pressure at the level of the landing strip and β being a predetermined value.
The present invention also relates to a method of guiding an aircraft during landing thereof on a landing strip, in the presence of a lateral alignment beam which is emitted from the ground and which gives an indication regarding the lateral alignment with respect to the landing strip.
According to the invention, this method is noteworthy in that the following series of successive operations is carried out repetitively up to landing:
Additionally, the present invention also relates to a device for determining at least one cue of vertical position of an aircraft during landing thereof on a landing strip, in the presence of a lateral alignment beam which is emitted from the ground and which gives an indication regarding the lateral alignment with respect to the landing strip. This device is noteworthy, according to the invention, in that it comprises:
Preferably, said first and second means form part of one and the same computation unit. Preferably also, said third and fourth means form part of one and the same computation unit.
The figures of the appended drawing will elucidate the manner in which the invention may be embodied. In these figures, identical references designate similar elements.
The device 1 in accordance with the invention and represented diagrammatically in
This lateral alignment beam 3 is a “loc” beam which is generally emitted by a directional VHF radiotransmitter, generally placed on the axis of the strip 2 at the opposite end from the approach threshold, which ensures azimuthal guidance along the approach axis according to an ideal lateral alignment profile during an “ILS” approach, this radiotransmitter emitting in a known manner two signals with different modulation which overlap on the approach axis where the two signals are received with equal strength.
This radiotransmitter forms part of a standard radionavigation system which generally comprises, moreover, at least one radiotransmitter which is able to emit a “glide” beam 4 for vertical guidance, as represented by dashed lines in
The present invention applies to the case where no “glide” beam 4 (vertical guidance) is available, only a “loc” beam 3 (lateral guidance) being detectable from the aircraft A.
Such a case can occur in the following situations:
To be able to obtain a cue of vertical position in such a case, said device 1 which is carried aboard the aircraft A comprises, according to the invention, as represented in
Thus, by virtue of said device 1 in accordance with the invention, a cue of vertical position of the aircraft (vertical deviation with respect to the prescribed position) is obtained solely on the basis of a lateral alignment beam 3 (“loc” beam), that is to say without using a vertical guidance beam 4 (“glide” beam).
According to the invention:
To do this, said means 9:
To do this, said means 14 preferably comprises:
In a preferred embodiment:
In a preferred embodiment, to determine the preset position of the aircraft A on the approach axis, one proceeds in the following manner. A first point corresponding to the aircraft's actual position (same latitude and longitude) determined by the means 14 is considered, in a horizontal plane. A straight line corresponding to the vertical projection, in this horizontal plane, of the approach axis determined by the means 9 is considered. A second point in this horizontal plane corresponding to the orthogonal projection of said first point onto this straight line is determined and a vertical plane orthogonal to this straight line and containing said second point is considered. The preset position of the aircraft on the approach axis corresponds to the intersection of this approach axis with this vertical plane.
Of course, a preferred but nonexclusive application of the device 1 in accordance with the invention relates to the guidance of an aircraft A during landing thereof.
In this case, said device 1 forms part of a guidance device 22 which moreover comprises, as represented in
Within the framework of the present invention, this guidance which consists in canceling out said vertical and lateral deviations may for example be similar to that performed in the case where the aircraft makes a standard “ILS” precision approach. According to a first embodiment, this guidance may be carried out by means of an automatic pilot of the aircraft A. According to a second embodiment, this guidance may be carried out by the pilot who is furnished with a so-called “flight director” indicator on a screen of the aircraft [for example a primary flight display “PFD”]. According to another embodiment, the pilot is furnished only with said lateral and vertical deviations with the aid of an appropriate means of information (for example a screen) and he corrects the trajectory of the aircraft A (by piloting the latter) in such a way as to cancel out these deviations.
Consequently, the user device 25 may therefore be, in particular, an automatic pilot, a screen or another standard means of information.
The guidance device 22 in accordance with the invention therefore makes it possible to perform guidance of the aircraft A in an aircraft approach phase and during landing, in a manner similar to guidance carried out during an “ILS” precision approach, in the particular and difficult case considered in the present invention (absence of “glide” beam). This makes it possible to reduce the pilot's workload, improves the ergonomics since the user interface is similar to that used for an “ILS” approach, and affords enhanced flight safety.
The guidance device 22 in accordance with the invention therefore affords an essential aid to landing, in particular through poor visibility (fog, etc.) or in the absence of visibility.
Various characteristics of the device 1 in accordance with the invention are specified hereinbelow.
In a preferred embodiment of the invention, the means of computation 20 corrects the altitude value measured by the barometric probe 19, as a function of the temperature on the ground.
To do this, said means of computation 20 corrects the altitude value Am measured, with the aid of the following expression, to obtain a corrected altitude value Ac:
Ac=(Am−Ap).(T1/T2)+Ap
in which:
In a first variant of this preferred embodiment, the value of the temperature T1 measured on the airport is communicated verbally to the pilot (by radio link with the airport's control tower) and the pilot enters this value into a computer (computation unit UC1 for example) of the aircraft A by means of an appropriate input device (not represented), for example an interface of “MCDU” (“Multipurpose Control Display Unit”) type. In a second variant, this value of the temperature T1 measured on the airport is transmitted to a computer (computation unit UC1 for example) of the aircraft A by means of a digital datalink (not represented), for example a radio link, between the air traffic control and the aircraft A. Preferably, the altitude correction according to the aforesaid expression is carried out only if the temperature on the ground T1 is below a predetermined temperature value, in particular the value T2.
This preferred embodiment has the advantage of automatically correcting the altitude of the aircraft A as a function of the temperature during guidance of this aircraft along an approach axis, whereas at present pilots have to correct this altitude using charts, in particular when they land on airports where the temperature is particularly low.
In another embodiment (which may be combined with the preferred embodiment described hereinabove for providing the altitude value Am used in the altitude correction formula corresponding to said preferred embodiment), the aircraft's altitude used for the computation of said vertical deviation is corrected (if necessary) so as to be referenced with respect to the level 28 of the sea 29 (so-called QNH altitude).
Such a correction is carried out in particular in two cases:
In a known manner, the corrected altitude QNH is then computed with the aid of the following expression (
QNH=STD+Δ with Δ=QNHp−β,
QNHp being a value dependent on the atmospheric pressure at the level of the landing strip 2 and β being a predetermined value.
In a first variant of this last embodiment, the value QNHp is communicated verbally to the pilot (for example by radio link with the airport's control tower) and the pilot enters this value into a computer (computation unit UC1 for example) of the aircraft A by means of an appropriate input device, for example an interface of “MCDU” type. In a second variant, this value is transmitted to a computer (computation unit UC1 for example) of the aircraft A by means of a digital datalink (not represented), for example a radio link, between the air traffic control and the aircraft A.
This embodiment has the advantage of using a single altitude reference whatever reference is chosen by the pilot. This facilitates guidance of the aircraft A. Specifically, guidance is generally performed with respect to waypoints, whose altitude (QNH) indicated on the approach maps is referenced with respect to the level 28 of the sea 29. Moreover, generally, the altitude of the reference point used for the determination of the approach axis is, itself, referenced with respect to the level 28 of the sea 29.
| Number | Date | Country | Kind |
|---|---|---|---|
| 03 03335 | Mar 2003 | FR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3521228 | Izumi et al. | Jul 1970 | A |
| 3697022 | Autechaud et al. | Oct 1972 | A |
| 3988731 | Young | Oct 1976 | A |
| 3999007 | Crane | Dec 1976 | A |
| 4004758 | Boriss et al. | Jan 1977 | A |
| 5593114 | Ruhl | Jan 1997 | A |
| 5820080 | Eschenbach | Oct 1998 | A |
| 6111526 | Aymeric et al. | Aug 2000 | A |
| 20030132860 | Feyereisen et al. | Jul 2003 | A1 |
| Number | Date | Country |
|---|---|---|
| 3621052 | Jan 1988 | DE |
