Indicator of a variable for aircraft

Details Indicator of a variable for aircraft Indicator of a variable for aircraft

2000-12-05

2002-08-27

Swarthout, Brent A. (Department: 2632)

Communications: electrical

Aircraft alarm or indicating systems

Nonalarm flight indicator

C340S973000, C701S005000, C701S014000

Reexamination Certificate

active

06441751

ABSTRACT:

The present invention relates to an indicator of a variable for an aircraft.
More particularly, although not exclusively, it relates to an indicator of altitude and of vertical speed (which is the derivative with respect to time of the variable representing the altitude) for an aircraft.
BACKGROUND OF THE INVENTION
It is known that for an aircraft, for example a helicopter or an airplane, when climbing (or descending), the acquisition of a given altitude, for example a flight level imposed by air control, is generally performed at a stable vertical speed.
On the approach to the intended altitude, the pilot of the aircraft progressively reduces its vertical speed so as to intercept said altitude with a vertical speed low enough to avoid any significant overshoot of the intended altitude.
This reduction in the vertical speed on approaching the intended altitude can be performed by intuition or with the help of empirical rules by monitoring the alterations (in position and in speed) of the altitude indication [needle for conventional instrumentation or index on symbology known in aeronautics by the acronym EFIS (Electronic Flight Instruments System)].
For example, a common empirical rule consists in commencing the reduction in the vertical speed on overstepping a fraction of the deviation between the intended altitude and the current altitude ({fraction (1/10)} for example), then in repeating this approach so as to progressively reduce the vertical speed.
Nevertheless, whatever strategy is used (intuition or with the help of an empirical rule), these methods require, on the one hand, good knowledge and good conduct of the performance of the aircraft and give rise, on the other hand, to a considerable work load in a phase of change of flight circumstance, that is to say when the pilot must devote himself to other tasks relating, for example, to air traffic or to navigation. Consequently, none of these known methods is satisfactory, the difficulties of organization and of gaging being due essentially to the fact that the standard instruments are not organized so as to depict an obvious summary of the situation.
DESCRIPTION OF THE PRIOR ART
To try to afford a solution to this problem, the documents EP-0 324 195 and FR-2 742 226 each disclose an altitude and vertical speed indicator making it possible to remedy, at least partially, the aforesaid drawbacks. To this end, the indicator disclosed by the document FR-2 742 226 comprises:
first and second sensors of altitude and vertical speed of the aircraft, respectively;
means for processing the signals delivered by said first and second sensors; and
means for displaying the processed signals depicting on a display screen:
altitude indication means, and
vertical speed indication means arranged opposite said altitude indication means,
said altitude indication means and said vertical speed indication means being coupled so that the altitude indication situated opposite the vertical speed indication represents, at any instant, a forthcoming altitude for the current vertical speed.
Thus, once the vertical speed indication arrives opposite the intended altitude indication, it is sufficient to keep the vertical speed indication locked onto the intended altitude indication until the latter is attained, this resulting in a progressive reduction in the vertical speed until an at least substantially zero vertical speed is reached. This known indicator consequently makes it possible to provide the pilot of the aircraft with an analog and coupled altitude and vertical speed indication, on a display screen, making it possible to guide any barometric (or radar) altitude capture without displaying the current value of the altitude of the aircraft, except when the intended altitude has actually been reached.
Moreover, in this known document FR-2 742 226, said altitude indication means consist of a graduated scale, rectilinearly (vertically) mobile past a fixed mark, and said vertical speed indication means consist of a needle mobile in rotation about the point of intersection of the extension of said fixed mark and of the extension of said needle and pointing toward said mobile scale, the angle defined by said fixed mark and said needle being representative of the value of the vertical speed.
Consequently, this known indicator enables the pilot of the aircraft to easily modulate the vertical speed so as to accurately capture and follow a desired altitude. At the moment of capture, the aircraft therefore exhibits a zero or substantially zero vertical speed.
Such a mode of interception, which is particularly advantageous for meeting up with a specified altitude or for capturing a trajectory with zero slope, cannot be applied to the interception of a trajectory exhibiting a nonzero slope since, with this known mode of interception, the aircraft captures the trajectory with a zero vertical speed, while this vertical speed ought to be such that it makes it possible to follow the trajectory (with nonzero slope) as soon as it is intercepted.
Also, to intercept a slopewise target trajectory, for example an approach trajectory, the pilot of the aircraft generally performs the following operations:
he determines beforehand by calculation the vertical speed factor making it possible to follow the slope while taking account of the ground speed of the aircraft;
he displays a vertical interception speed making it possible to converge toward the slopewise trajectory; and
on the approach to the slopewise trajectory, he progressively modulates the vertical speed, on the one hand so as to intercept said trajectory without significant overshoot and, on the other hand, so as to alter his vertical speed from the interception value to the value for following (also determined beforehand by calculation).
Once the interception has been achieved, the same strategy is applied each time the aircraft exhibits a significant deviation with respect to the target trajectory.
This known method of intercepting a slopewise target trajectory thus exhibits the same drawbacks as those stated above relating to the known methods of approach, by intuition or with the help of empirical rules, to a specified altitude. In particular, it requires, on the one hand, good knowledge and good conduct of the performance of the aircraft and gives rise, on the other hand, to a considerable work load in a particular phase of flight, in which the pilot generally has to devote himself to other tasks relating, for example to air traffic or to navigation. This known method of intercepting a target trajectory exhibiting a nonzero slope is therefore scarcely satisfactory.
SUMMARY OF THE INVENTION
The object of the present invention is to remedy these drawbacks. It relates to an indicator of a variable for an aircraft, providing a pilot of the aircraft with a visual guide which is integrated into an environment which is familiar to him and which enables him to anticipate and to gage in an optimal manner the piloting of the aircraft so as to capture and follow a target trajectory.
To this end, the indicator of a variable and its derivative for an aircraft, comprising:
first means for determining the variable and its derivative with respect to time; and
display means which depict on a display screen:
to indicate said variable, a graduated scale which bears values relating to said variable and which is rectilinearly mobile past a fixed mark, marking the value of said variable of said aircraft; and
to indicate said derivative, an indicator element,
is noteworthy in that it furthermore comprises second means for determining a first target value relating to said variable and a second target value relating to said derivative, and wherein said display means furthermore depict on said display screen:
a first means of indication of the first target value, which is arranged in such a way as to indicate said first target value on said graduated scale; and
a second means of indication of the second target value, which is associated at least with said indicator element so that, when the latter points toward said seco

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