Communications: electrical – Aircraft alarm or indicating systems – Flight alarm
Patent
1996-07-30
1998-08-25
Swarthout, Brent A.
Communications: electrical
Aircraft alarm or indicating systems
Flight alarm
340961, 364461, G08B 2300
Patent
active
057987122
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and a device for supplying information, an alert or alarm for an aircraft maneuvering above terrain with known relief, particularly in the vicinity of a runway for the aircraft, when the trajectory of the aircraft is capable of intercepting a relief of said terrain.
DESCRIPTION OF RELATED ART
It has proved to be necessary, for aircraft in flight, to provide an alarm system making it possible, in good time, to detect and signal proximity of the relief (in a general way, of the ground), which is a danger to the aircraft. A currently widespread system is GPWS, standing for "Ground Proximity Warning System". GPWS uses the radio altimeter measurement of the height of the aircraft above the ground situated in the vertical to its instantaneous position. The comparison of these radio-altimeter data and the vertical speed parameters, among others (pitot-static vertical speed and radio altimeter rate of approach to the ground), with respect to various predetermined thresholds, allows various types of visual and audible alarms to be triggered. Alarms make it possible to warn the pilot of a dangerous situation risking a collision with the ground in the near future if no corrective action is taken on the controls making it possible rapidly to regain sufficient altitude to guarantee the safety of the aircraft. The main drawback of this system lies in the high number of false alarms which it generates.
Another system of this type is also known, but based on a different principle from that used by GPWS, to evaluate the level of danger which the ground represents for the aircraft. In this case, the measured position of the aircraft in the horizontal and vertical planes is used so as to calculate a prediction of the changes in the various possible trajectories of the aircraft in the moments which follow the measurement, and to compare the envelope of these trajectories with the safety altitudes described in a ground-related database, calculated, particularly, from the various heights of the surface of the ground overflown by the predicted trajectories.
The detection of an intersection between the envelope of trajectories and the safety volume defined by the ground-related database makes it possible to predict that the aircraft risks departing from the range of safety altitudes in a time interval which is determined in advance. An alert or alarm can then be generated so as to warn the pilot of this danger situation so that he returns to an acceptable safety altitude as rapidly as possible.
In this system, the ground (terrain)-related database consists of the recording of safety altitudes corresponding to each of the meshes of the grid describing the terrain. The grid defines subdivisions of the surface of the earth which, for example, may be referenced in geographic coordinates. The grid then consists of a network of adjacent meshes. Each mesh has a safety altitude attributed to it, guaranteeing that overflying this mesh, at least at this altitude, will entail no collision with the terrain described in this mesh. The main drawback of this system lies in the short timescale left to the crew to react to certain rapid variations in the relief which are associated with a number, which may be high, of false alarms which they generate.
The alarm is generated based on the detection of a "conflict" (interception) between the trajectory of the aircraft and the relief of an element (mesh) of the ground- or terrain-related database.
The position (in terms of Ox, Oy and Oz coordinates) of the aircraft is extrapolated for an all-inclusive maximum anticipation time of the order of one minute or less (for example 30 or 60 seconds) along the direction of the ground speed vector (speed with respect to the ground).
This timescale has been chosen inclusively in order to include the following reaction times: vigilance is variable in the course of a flight; surfaces; on configuration (gears, flaps, engine failure, particularly);
Prediction of the aircraft's trajectory is obtain
REFERENCES:
patent: 3936796 (1976-02-01), Bateman
patent: 4224669 (1980-09-01), Brame
patent: 4646244 (1987-02-01), Bateman et al.
patent: 4914436 (1990-04-01), Bateman et al.
patent: 4916448 (1990-04-01), Thor
patent: 5414631 (1995-05-01), Denoize et al.
patent: 5442556 (1995-08-01), Boyes et al.
patent: 5448233 (1995-09-01), Saban et al.
patent: 5488563 (1996-01-01), Chazelle et al.
Aviation Week & Space Technology, "Terrain Alert Graphics Tested on Cockpit Displays", Paul Proctor, Aug. 8, 1994, p. 51.
Aerospatiale - Societe Nationale Industrielle
Swarthout Brent A.
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