CA1240771A - Warning system for tactical rotary wing aircraft - Google Patents
Warning system for tactical rotary wing aircraftInfo
- Publication number
- CA1240771A CA1240771A CA000451452A CA451452A CA1240771A CA 1240771 A CA1240771 A CA 1240771A CA 000451452 A CA000451452 A CA 000451452A CA 451452 A CA451452 A CA 451452A CA 1240771 A CA1240771 A CA 1240771A
- Authority
- CA
- Canada
- Prior art keywords
- airspeed
- warning
- aircraft
- altitude
- warning system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
- G01C5/005—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels altimeters for aircraft
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Emergency Alarm Devices (AREA)
- Radar Systems Or Details Thereof (AREA)
- Traffic Control Systems (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
WARNING SYSTEM FOR TACTICAL ROTARY WING AIRCRAFT
Abstract of the Disclosure A warning system for rotary wing aircraft that monitors the altitude above ground of the aircraft and issues a warning when there is insufficient terrain clearance. The warning criteria are optimized for rotary wing aircraft and are altered as a function of landing gear position and airspeed. Two distinct warnings are given. One indicates insufficient terrain clearance and the other warns the pilot if he attempts to land with the landing gear up. Logic circuitry is provided to modify the criteria necessary to gener-ate a warning, and to inhibit certain warnings, as required by the mode of operation of the aircraft.
Abstract of the Disclosure A warning system for rotary wing aircraft that monitors the altitude above ground of the aircraft and issues a warning when there is insufficient terrain clearance. The warning criteria are optimized for rotary wing aircraft and are altered as a function of landing gear position and airspeed. Two distinct warnings are given. One indicates insufficient terrain clearance and the other warns the pilot if he attempts to land with the landing gear up. Logic circuitry is provided to modify the criteria necessary to gener-ate a warning, and to inhibit certain warnings, as required by the mode of operation of the aircraft.
Description
~2a~
BACKGROUND OF THE INVENTION
Field of the Invention -This invention relates generally to ground proximity warning systems, and more particularly to a ground proximity warning system for providing the pilot of a rotary wing aircraft with a warning in the I event of insufficient terrain clearance, or if a landing ; with the landing gear up is attempted.
Descrlption of the Prior Art Systems for providing the pilot of an air-craft with a warning in the event of insufficient terrain clearance or if a gear up landing is attempted are known. Examples of such systems are disclosed in United States Patent Nos. 3,934,221, 3,934,222, 3,944,968 and 4,030/065 assigned to the assignee of the present invention.
While these systems do provide warnings in the event of insufficient terrain clearance, these systems are designed primarily for use with transport aircraft, and are not readily applicable to rotary wing aircraft whose flight and operational characteristics are substantially different than those of transport aircraft.
SUMMARY OF THE INVENTION
_ Therefore, it is an object of the present invention to provide a warning system that overcomes many of the disadvantages of the prior art warning systems.
7~.
It is yet another object of the present invention to provide a warning to the pilot of a rotary wing aircraft in the 2vent of insufficient terraln clearance It is yet another object of the present invention to provide a warning system that warns the pilot of a rotary wing aircraft if he attempts to land with the landing gear up.
It is yet another object of the present invention to provide a warning system for alerting the pilot of a rotary wing aircraft of an insufficient terrain clearance condition wherein the warning criteria are optimized for the performance and opera-tional characteristics of rotary wing aircraft Therefore, in accordance with a preferred embodiment of the invention there is provided a system that monitors the altitude above ground and airspeed of the aircraft and generates a voice warning such as "TOO LOW TERRAIN" when the altitude above ground of the aircraft is insufficient for the airspeed at which the aircraft is flying. The criteria required to generate a warning are modified when the landing gear is up, and a second distinct warning such as "TOO LOW
GEAR" is generated if the pilot attempts to land with the landing gear up.
These and other objects and advantages of the present invention will become readily apparent upon consideration of the following detailed descrip-tion and attached drawing, wherein:
FIG. 1 is a logical block diagram of the portion of the system according to the invention that generates a warning in the event of insufficient terrain clearance;
~2~77~L.
FIG. 2 is a graph illustrating the relation-ship between the airspeed of the aircraft and the altitude above ground required to generate a warning when the landing gear is up; and FIG. 3 is a graph illustrating the relation-ship between the airspeed of the aircraft and the altitude above ground of the aircraft required to generate a warning when the landing gear of the air-craft is down.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, with particular attention to FIG. 1, there is illustrated an embodiment of the insufficient terrain clearance portion of the warning system according to the invention generally designated by the reference numeral 10. The system 10 according to the invention is illustrated in FIG.
1 in logical block diagram form as a series of gates, comparators, flip-flops and the like for purposes of illustration; however, it should be understood that the actual implementation of the system can be other than as shown in FIG. 1, with various digital and analog implementations being possible. The signals used by the warning system as described include radio altitude and airspeed along with a signal representa-tive of the position of the landing gear, various discrete signals indicating the mode of operation of the aircraft, for example, tactical or non-tactical or mine counter measures (MCM), and various validity signals. Depending on the type of aircraft in which the warning Cystem is installed, the signals shown in FIG. 1 can be obtained from individual instruments such as a radio altimeter 12, an airspeed signal source 14, such as, for example, an air data computer or an airspeed indicator, and various discrete elements such as a switch indicating the position of the landing gear, a tactlcal mission switch and a mine counter measures IMCM) switch. Alternatively, these signals may be obtained from a digital data bus in certain newer aircraft.
As previously discussed, the warning system according to the invention provides two different insufficient terrain clearance warnings according to two different warning criteria depending upon whether the landing gear of the aircraft is up or down. In the illustrated embodiment, the warning criteria for the gear up configuration are defined by a gear up warning comparator 16, while the criteria for generating the warning in a gear down configuration are defined by a gear down comparator 18. Both of the comparators 16 and 18 receive signals representative ox the altitude above ground of the aircraft from the radio altimeter 12 and a signal representative of the airspeed of the aircraft from the airspeed signal source 14, and generate a warning initiation signal when the relation-ship between altitude above ground and airspeed is such that insufficient terrain clearance exists.
In order to avoid nuisance warnings, the system according to the invention is disabled during take-off. The disabling function is accomplished by a take-off flip-flop 20 that is set during take-off and reset during other phases of flight. The flip-flop 20 is set by an AND gate 22 when the landing gear is down, and the aircraft is below 100 feet of radio altitude, and if either the speed of the aircraft is below 40 knots or the aircraft is below 10 feet as is indicated by signals applied to an OR gate 24.
The flip-flop 20 is reset by an OR gate 26 once the altitude above ground of the aircraft exceeds 200 feet, or the tactical inhibit signal indicating a tactical mission is applied to the gate 26. The ` ~2~7~.
various signals representative of various airspeeds and altitudes are provided by an airspeed comparator 28 and an altitude comparator 3~. The airspeed compar-ator 28 receives signals from the airspeed signal source 14, and compares the airspeed signal with a reference signal representative of a predetermined airspeed, such as, for example, 40 knots, and provides a signal to the gate 24 whenever the airspeed is greater than 40 knots. Similarly, the altitude comparator 30 compares the altitude signals received from the radio altimeter 12 with various internally (or externally) generated reverence signals representative of various altitudes, and provides various output signals repre-sentative of whether the altitude is above or below the various reference altitudes. For example, the altitude comparator 30 provides output signals repre-sentative of when the airGraft is below 10 feet, above 10 feet, below 100 feet and above 200 feet of radio altitude to various gates in the logic circuitry.
The system is inhibited by the master inhibit signal which inhibits a pair of gates 30 and 32 in the event of a faulty instrument. In addition, the gates 32 and 34 are inhibited during tactical opera-tions by the tactical inhibit signal, and when the aircraft is below 10 feet of radio altitude by the absence of the greater than 10 foot enabling signal.
The gate 32 is enabled by a gear up signal when the aircraft landing gear is up in order to put the system under the control of the gear up comparator 16. The AND gate 34 is enabled by the gear down signal to place the system under the control of the gear down warning comparator 18 when the gear is down. In addi-tion, the gate 32 is inhibited by an OR gate 36 under various flight conditions, including mine counter measures and tactical maneuvers, and if the pilot ~,4~7~
desires to cancel the gear up warning. The inhibiting function is provided by the mine counter measures (MCM) inhibit signal, the gear up cancel signal and the tactical inhibit signal.
When the aircraft is flying with its gear up and it is not in a take-off mode, and the other enabling conditions have been met, the AND gate 32 is under the control of the gear up warning comparator 16 which generates the warning initiation signal and applies it via the gate 32 to a first voice generator 38 and an AND gate 40 whenever the criteria indicating insufficient terrain clearance are exceeded. As long as the airspeed of the aircraft is below a predetermined airspeed, for example, 120 knots, the AND gate 40 is inhibited, thus preventing the warning initiation signal from being applied to a second warning generator 42. The first warning generator 38 is responsive to the warning initiation signal received from the AND
gate 32 and generates a voice signal, such as, for example, "TOO LOW GEAR", and applies it to a transducer 44 which may be a loudspeaker, an earphone or the like to provide a voice warning to the pilot. Although FIG. 1 shows the signal from the generator 38 being applied directly to the transducer 44, the signal may also be applied indirectly, for example, via the air-craft intercom system.
When the airspeed of the aircraft exceeds a predetermined airspeed, such as, for example, 120 knots, indicating that the aircraft is in a cruise rather than in a landing mode of operation, the AND
gate 40 is enabled by the greater than 120 knot signal.
This permits the warning initiation signal from the AND glte 32 to be applied to the TOO LOW TERRAIN
warning generator 42 to cause the "TOO LOW TERRAIN"
warning to be generated and applied to the transducer 44. The generator 42 also inhibits the generator 38 when the "TOO LOW TERRAIN" warning is being generated to avoid confusing the pilot. Thus, when the speed of the aircraft is below 120 knots, indicative of a landing, any warning generated will be "TOO LOW GEAR".
At an airspeed above 120 knots, which is indicative of a cruise mode of operation, any warning generated will be "TOO LOW TERRAIN".
When the landing gear is down, the AND gate 32 is inhibited, and the AND gate 34 is enabled to thereby place the TOO LOW TERRAIN warning generator 42 under the control of the gear down warning comparator 18 via the END gate 34~ Consequently, the warning criteria will be determined by the gear down warning comparator 18, and any warning generated will be "TOO
LOW TERRAIN".
In the illustrated embodiment, the gear up warning comparator 16 and the gear down warning compar-ator 18 have been shown as two separate comparators;
however, both functions can be implemented in a signal comparator whose warning criteria are modified depend-ing on whether the gear is up or down. Similarly, the TOO LOW GEAR warning generator 38 and the TOO LOW
TERRAIN warning generator 42 are shown as two separate warning generators, but a single warning generator capable of generating two distinct warnings can also be used.
The relationships between radio altitude and airspeed required to generate a warning are illus-trated by the shaded areas of FIG. 2. Below an air-speed of approximately 150 knots, the "TOO LOW GEAR"
warning is generated, and above approximately 120 knots airspeed the "TOO LOW TERRAIN" warning is generated. Below approximately 40 knots of airspeed, the "TOO LOW GEM" warning is generated when the alti-~3LZ,~7~.
tude above ground of the aircraft drops below approxi-mately 150 feet. The altitude required to generate the warning drops linearly with airspeed above approxi-mately 40 knots until an airspeed of approximately 120 knots is reached, at which point the "TOO LOW
GEAR" warning is generated at an altitude of approxi-mately 75 feet above the ground. the reason for the particular shape of the curve is to maximize the warning time when the pilot is actually landing, and to minimize nuisance warnings when low level maneuvers are being performed, since such maneuvers are generally performed at airspeeds in excess of approximately 40 knots. Above an airspeed of approximately 120 knots the "TOO LOW TERRAIN" warning is generated whenever the radio altitude drops below approximately 75 feet regardless of airspeed, provided that the airspeed exceeds approximately 120 knots.
The relationship between radio altitude and airspeed required to generate a warning in the gear down mode of operation is shown by the shaded portion of the graph of FIG. 3. Because the gear is down already, no "TOO LOW GEAR" warning is generated, and the only warning generated is "TOO LOW TERRAIN". Above an airspeed of approximately 120 knots, dropping below a radio altitude of approximately 100 feet will cause the warning to be generated. This altitude is somewhat higher than the altitude required to generate the warning in the gear up case, because helicopters generally have their landing gear down when performing low level maneuvers. Below approximately 120 knots airspeed, the altitude at which the warning is generated decreases linearly until the warning altitude is reduced to 10 feet at an airspeed of 58 knots. Below an air-speed of 58 knots, no warning is given in order to permit nuisance warning free, low speed, low level I` ~2~ 7~
9, maneuvering. Also, the warnings are inhibited below 10 feet of radio altitude for both the gear up and the gear down modes of operation in order to avoid nuisance warnings caused by erratic radio altitude signals at low altitudes.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings Thus, it is to be understood that, within the scope of the append:ed claims,the invention may be practiced otherwise than as specifically described above.
BACKGROUND OF THE INVENTION
Field of the Invention -This invention relates generally to ground proximity warning systems, and more particularly to a ground proximity warning system for providing the pilot of a rotary wing aircraft with a warning in the I event of insufficient terrain clearance, or if a landing ; with the landing gear up is attempted.
Descrlption of the Prior Art Systems for providing the pilot of an air-craft with a warning in the event of insufficient terrain clearance or if a gear up landing is attempted are known. Examples of such systems are disclosed in United States Patent Nos. 3,934,221, 3,934,222, 3,944,968 and 4,030/065 assigned to the assignee of the present invention.
While these systems do provide warnings in the event of insufficient terrain clearance, these systems are designed primarily for use with transport aircraft, and are not readily applicable to rotary wing aircraft whose flight and operational characteristics are substantially different than those of transport aircraft.
SUMMARY OF THE INVENTION
_ Therefore, it is an object of the present invention to provide a warning system that overcomes many of the disadvantages of the prior art warning systems.
7~.
It is yet another object of the present invention to provide a warning to the pilot of a rotary wing aircraft in the 2vent of insufficient terraln clearance It is yet another object of the present invention to provide a warning system that warns the pilot of a rotary wing aircraft if he attempts to land with the landing gear up.
It is yet another object of the present invention to provide a warning system for alerting the pilot of a rotary wing aircraft of an insufficient terrain clearance condition wherein the warning criteria are optimized for the performance and opera-tional characteristics of rotary wing aircraft Therefore, in accordance with a preferred embodiment of the invention there is provided a system that monitors the altitude above ground and airspeed of the aircraft and generates a voice warning such as "TOO LOW TERRAIN" when the altitude above ground of the aircraft is insufficient for the airspeed at which the aircraft is flying. The criteria required to generate a warning are modified when the landing gear is up, and a second distinct warning such as "TOO LOW
GEAR" is generated if the pilot attempts to land with the landing gear up.
These and other objects and advantages of the present invention will become readily apparent upon consideration of the following detailed descrip-tion and attached drawing, wherein:
FIG. 1 is a logical block diagram of the portion of the system according to the invention that generates a warning in the event of insufficient terrain clearance;
~2~77~L.
FIG. 2 is a graph illustrating the relation-ship between the airspeed of the aircraft and the altitude above ground required to generate a warning when the landing gear is up; and FIG. 3 is a graph illustrating the relation-ship between the airspeed of the aircraft and the altitude above ground of the aircraft required to generate a warning when the landing gear of the air-craft is down.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, with particular attention to FIG. 1, there is illustrated an embodiment of the insufficient terrain clearance portion of the warning system according to the invention generally designated by the reference numeral 10. The system 10 according to the invention is illustrated in FIG.
1 in logical block diagram form as a series of gates, comparators, flip-flops and the like for purposes of illustration; however, it should be understood that the actual implementation of the system can be other than as shown in FIG. 1, with various digital and analog implementations being possible. The signals used by the warning system as described include radio altitude and airspeed along with a signal representa-tive of the position of the landing gear, various discrete signals indicating the mode of operation of the aircraft, for example, tactical or non-tactical or mine counter measures (MCM), and various validity signals. Depending on the type of aircraft in which the warning Cystem is installed, the signals shown in FIG. 1 can be obtained from individual instruments such as a radio altimeter 12, an airspeed signal source 14, such as, for example, an air data computer or an airspeed indicator, and various discrete elements such as a switch indicating the position of the landing gear, a tactlcal mission switch and a mine counter measures IMCM) switch. Alternatively, these signals may be obtained from a digital data bus in certain newer aircraft.
As previously discussed, the warning system according to the invention provides two different insufficient terrain clearance warnings according to two different warning criteria depending upon whether the landing gear of the aircraft is up or down. In the illustrated embodiment, the warning criteria for the gear up configuration are defined by a gear up warning comparator 16, while the criteria for generating the warning in a gear down configuration are defined by a gear down comparator 18. Both of the comparators 16 and 18 receive signals representative ox the altitude above ground of the aircraft from the radio altimeter 12 and a signal representative of the airspeed of the aircraft from the airspeed signal source 14, and generate a warning initiation signal when the relation-ship between altitude above ground and airspeed is such that insufficient terrain clearance exists.
In order to avoid nuisance warnings, the system according to the invention is disabled during take-off. The disabling function is accomplished by a take-off flip-flop 20 that is set during take-off and reset during other phases of flight. The flip-flop 20 is set by an AND gate 22 when the landing gear is down, and the aircraft is below 100 feet of radio altitude, and if either the speed of the aircraft is below 40 knots or the aircraft is below 10 feet as is indicated by signals applied to an OR gate 24.
The flip-flop 20 is reset by an OR gate 26 once the altitude above ground of the aircraft exceeds 200 feet, or the tactical inhibit signal indicating a tactical mission is applied to the gate 26. The ` ~2~7~.
various signals representative of various airspeeds and altitudes are provided by an airspeed comparator 28 and an altitude comparator 3~. The airspeed compar-ator 28 receives signals from the airspeed signal source 14, and compares the airspeed signal with a reference signal representative of a predetermined airspeed, such as, for example, 40 knots, and provides a signal to the gate 24 whenever the airspeed is greater than 40 knots. Similarly, the altitude comparator 30 compares the altitude signals received from the radio altimeter 12 with various internally (or externally) generated reverence signals representative of various altitudes, and provides various output signals repre-sentative of whether the altitude is above or below the various reference altitudes. For example, the altitude comparator 30 provides output signals repre-sentative of when the airGraft is below 10 feet, above 10 feet, below 100 feet and above 200 feet of radio altitude to various gates in the logic circuitry.
The system is inhibited by the master inhibit signal which inhibits a pair of gates 30 and 32 in the event of a faulty instrument. In addition, the gates 32 and 34 are inhibited during tactical opera-tions by the tactical inhibit signal, and when the aircraft is below 10 feet of radio altitude by the absence of the greater than 10 foot enabling signal.
The gate 32 is enabled by a gear up signal when the aircraft landing gear is up in order to put the system under the control of the gear up comparator 16. The AND gate 34 is enabled by the gear down signal to place the system under the control of the gear down warning comparator 18 when the gear is down. In addi-tion, the gate 32 is inhibited by an OR gate 36 under various flight conditions, including mine counter measures and tactical maneuvers, and if the pilot ~,4~7~
desires to cancel the gear up warning. The inhibiting function is provided by the mine counter measures (MCM) inhibit signal, the gear up cancel signal and the tactical inhibit signal.
When the aircraft is flying with its gear up and it is not in a take-off mode, and the other enabling conditions have been met, the AND gate 32 is under the control of the gear up warning comparator 16 which generates the warning initiation signal and applies it via the gate 32 to a first voice generator 38 and an AND gate 40 whenever the criteria indicating insufficient terrain clearance are exceeded. As long as the airspeed of the aircraft is below a predetermined airspeed, for example, 120 knots, the AND gate 40 is inhibited, thus preventing the warning initiation signal from being applied to a second warning generator 42. The first warning generator 38 is responsive to the warning initiation signal received from the AND
gate 32 and generates a voice signal, such as, for example, "TOO LOW GEAR", and applies it to a transducer 44 which may be a loudspeaker, an earphone or the like to provide a voice warning to the pilot. Although FIG. 1 shows the signal from the generator 38 being applied directly to the transducer 44, the signal may also be applied indirectly, for example, via the air-craft intercom system.
When the airspeed of the aircraft exceeds a predetermined airspeed, such as, for example, 120 knots, indicating that the aircraft is in a cruise rather than in a landing mode of operation, the AND
gate 40 is enabled by the greater than 120 knot signal.
This permits the warning initiation signal from the AND glte 32 to be applied to the TOO LOW TERRAIN
warning generator 42 to cause the "TOO LOW TERRAIN"
warning to be generated and applied to the transducer 44. The generator 42 also inhibits the generator 38 when the "TOO LOW TERRAIN" warning is being generated to avoid confusing the pilot. Thus, when the speed of the aircraft is below 120 knots, indicative of a landing, any warning generated will be "TOO LOW GEAR".
At an airspeed above 120 knots, which is indicative of a cruise mode of operation, any warning generated will be "TOO LOW TERRAIN".
When the landing gear is down, the AND gate 32 is inhibited, and the AND gate 34 is enabled to thereby place the TOO LOW TERRAIN warning generator 42 under the control of the gear down warning comparator 18 via the END gate 34~ Consequently, the warning criteria will be determined by the gear down warning comparator 18, and any warning generated will be "TOO
LOW TERRAIN".
In the illustrated embodiment, the gear up warning comparator 16 and the gear down warning compar-ator 18 have been shown as two separate comparators;
however, both functions can be implemented in a signal comparator whose warning criteria are modified depend-ing on whether the gear is up or down. Similarly, the TOO LOW GEAR warning generator 38 and the TOO LOW
TERRAIN warning generator 42 are shown as two separate warning generators, but a single warning generator capable of generating two distinct warnings can also be used.
The relationships between radio altitude and airspeed required to generate a warning are illus-trated by the shaded areas of FIG. 2. Below an air-speed of approximately 150 knots, the "TOO LOW GEAR"
warning is generated, and above approximately 120 knots airspeed the "TOO LOW TERRAIN" warning is generated. Below approximately 40 knots of airspeed, the "TOO LOW GEM" warning is generated when the alti-~3LZ,~7~.
tude above ground of the aircraft drops below approxi-mately 150 feet. The altitude required to generate the warning drops linearly with airspeed above approxi-mately 40 knots until an airspeed of approximately 120 knots is reached, at which point the "TOO LOW
GEAR" warning is generated at an altitude of approxi-mately 75 feet above the ground. the reason for the particular shape of the curve is to maximize the warning time when the pilot is actually landing, and to minimize nuisance warnings when low level maneuvers are being performed, since such maneuvers are generally performed at airspeeds in excess of approximately 40 knots. Above an airspeed of approximately 120 knots the "TOO LOW TERRAIN" warning is generated whenever the radio altitude drops below approximately 75 feet regardless of airspeed, provided that the airspeed exceeds approximately 120 knots.
The relationship between radio altitude and airspeed required to generate a warning in the gear down mode of operation is shown by the shaded portion of the graph of FIG. 3. Because the gear is down already, no "TOO LOW GEAR" warning is generated, and the only warning generated is "TOO LOW TERRAIN". Above an airspeed of approximately 120 knots, dropping below a radio altitude of approximately 100 feet will cause the warning to be generated. This altitude is somewhat higher than the altitude required to generate the warning in the gear up case, because helicopters generally have their landing gear down when performing low level maneuvers. Below approximately 120 knots airspeed, the altitude at which the warning is generated decreases linearly until the warning altitude is reduced to 10 feet at an airspeed of 58 knots. Below an air-speed of 58 knots, no warning is given in order to permit nuisance warning free, low speed, low level I` ~2~ 7~
9, maneuvering. Also, the warnings are inhibited below 10 feet of radio altitude for both the gear up and the gear down modes of operation in order to avoid nuisance warnings caused by erratic radio altitude signals at low altitudes.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings Thus, it is to be understood that, within the scope of the append:ed claims,the invention may be practiced otherwise than as specifically described above.
Claims (11)
1. A ground proximity warning system for alerting the pilot of a rotary wing aircraft of insufficient terrain clearance, comprising:
means for receiving a signal representative of the airspeed of the aircraft;
means for receiving a signal representative of the altitude above ground of the aircraft; and means responsive to the airspeed signal and altitude above ground signal receiving means for generating a warning if the altitude above ground of the aircraft is below an airspeed-dependent threshold altitude, wherein the threshold altitude varies from a first altitude above ground at a first airspeed to a second altitude above ground, lower than the first, at a second, higher airspeed.
means for receiving a signal representative of the airspeed of the aircraft;
means for receiving a signal representative of the altitude above ground of the aircraft; and means responsive to the airspeed signal and altitude above ground signal receiving means for generating a warning if the altitude above ground of the aircraft is below an airspeed-dependent threshold altitude, wherein the threshold altitude varies from a first altitude above ground at a first airspeed to a second altitude above ground, lower than the first, at a second, higher airspeed.
2. A warning system according to claim 1, wherein the threshold altitude varies linearly with changing airspeed for airspeeds between the first and second air speeds.
3. A warning system according to claim 2, wherein the first altitude above ground and the first airspeed are approximately 150 feet (46 metres) and approximately knots (21 metres per second) respectively, and the second altitude above ground and the second airspeed are
3. A warning system according to claim 2, wherein the first altitude above ground and the first airspeed are approximately 150 feet (46 metres) and approximately knots (21 metres per second) respectively, and the second altitude above ground and the second airspeed are
Claim 3 continued....
approximately 75 feet (23 metres) and approximately 120 knots (62 metres per second) respectively.
approximately 75 feet (23 metres) and approximately 120 knots (62 metres per second) respectively.
4. A warning system according to claim 1, further comprising means for varying the nature of the warning generated, from a first warning if the aircraft is flying below a threshold airspeed to a second warning, distinguishable from the first, if the aircraft is flying above the threshold airspeed.
5. A warning system according to claim 4, wherein the threshold airspeed is approximately 120 knots (62 metres per second).
6. A warning system according to claim 4, wherein the threshold airspeed is the said second airspeed.
7. A warning system according to claim 1, 2 or 3 further comprising means for inhibiting the warning at altitudes above ground below approximately 10 feet (3 metres).
8. A warning system according to claim 1, 2 or 3 further comprising means for inhibiting the warning during a take-off phase of flight of the aircraft.
9. A warning system according to claim 1, further comprising:
9. A warning system according to claim 1, further comprising:
Claim 9 continued....
means for receiving a landing gear signal representative of the position of retractible landing gear of the aircraft; and means for varying the airspeed-dependent threshold altitude in response to the landing gear signal, to establish when the landing gear is down a redefined threshold altitude which increases with increasing airspeed.
means for receiving a landing gear signal representative of the position of retractible landing gear of the aircraft; and means for varying the airspeed-dependent threshold altitude in response to the landing gear signal, to establish when the landing gear is down a redefined threshold altitude which increases with increasing airspeed.
10. A warning system according to claim 9, wherein the redefined threshold altitude increases linearly with increasing airspeeds.
11. A warning system according to claim 9 or claim 10, wherein the redefined threshold altitude increases from approximately 10 feet (3 metres) above ground and an airspeed of approximately 58 knots (30 metres per second) to approximately 100 feet (30 metres) above ground at an airspeed of approximately 120 knots (62 metres per second).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50321683A | 1983-06-10 | 1983-06-10 | |
| US503,216 | 1983-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1240771A true CA1240771A (en) | 1988-08-16 |
Family
ID=24001189
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000451452A Expired CA1240771A (en) | 1983-06-10 | 1984-04-06 | Warning system for tactical rotary wing aircraft |
Country Status (14)
| Country | Link |
|---|---|
| JP (1) | JPS608196A (en) |
| AU (1) | AU548266B2 (en) |
| BE (1) | BE899876A (en) |
| CA (1) | CA1240771A (en) |
| CH (1) | CH660159A5 (en) |
| DE (1) | DE3421517A1 (en) |
| FI (1) | FI841931A (en) |
| FR (1) | FR2553507B1 (en) |
| GB (1) | GB2141683B (en) |
| GR (1) | GR81645B (en) |
| IT (1) | IT1179182B (en) |
| NL (1) | NL8401856A (en) |
| NZ (1) | NZ207888A (en) |
| SE (1) | SE8403093L (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3944968A (en) * | 1974-11-01 | 1976-03-16 | Sundstrand Data Control, Inc. | Aircraft ground proximity warning system having speed versus altitude compensation |
| IL48315A (en) * | 1975-03-18 | 1978-08-31 | United Technologies Corp | Warning system for helicopters for avoiding tail contact during landing |
| US4030065A (en) * | 1976-07-19 | 1977-06-14 | Sundstrand Corporation | Terrain clearance warning system for aircraft |
| JPS53114981A (en) * | 1977-03-17 | 1978-10-06 | Santo Tekkosho Kk | Continuous fabric conveying apparatus |
| US4567483A (en) * | 1982-12-10 | 1986-01-28 | Sundstrand Data Control, Inc. | Position based ground proximity warning system for aircraft |
-
1984
- 1984-04-06 CA CA000451452A patent/CA1240771A/en not_active Expired
- 1984-04-18 NZ NZ207888A patent/NZ207888A/en unknown
- 1984-05-14 FI FI841931A patent/FI841931A/en not_active Application Discontinuation
- 1984-05-14 FR FR8407408A patent/FR2553507B1/en not_active Expired
- 1984-05-21 GB GB08412991A patent/GB2141683B/en not_active Expired
- 1984-05-30 AU AU28842/84A patent/AU548266B2/en not_active Ceased
- 1984-06-06 CH CH2762/84A patent/CH660159A5/en not_active IP Right Cessation
- 1984-06-07 IT IT48342/84A patent/IT1179182B/en active
- 1984-06-07 GR GR74951A patent/GR81645B/el unknown
- 1984-06-08 BE BE0/213110A patent/BE899876A/en not_active IP Right Cessation
- 1984-06-08 DE DE3421517A patent/DE3421517A1/en not_active Ceased
- 1984-06-08 JP JP59116819A patent/JPS608196A/en active Pending
- 1984-06-08 SE SE8403093A patent/SE8403093L/en not_active Application Discontinuation
- 1984-06-12 NL NL8401856A patent/NL8401856A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| SE8403093L (en) | 1984-12-11 |
| AU2884284A (en) | 1984-12-13 |
| FR2553507A1 (en) | 1985-04-19 |
| CH660159A5 (en) | 1987-03-31 |
| AU548266B2 (en) | 1985-12-05 |
| IT8448342A0 (en) | 1984-06-07 |
| FI841931A0 (en) | 1984-05-14 |
| NL8401856A (en) | 1985-01-02 |
| DE3421517A1 (en) | 1984-12-13 |
| GB2141683B (en) | 1986-10-15 |
| FR2553507B1 (en) | 1988-11-10 |
| JPS608196A (en) | 1985-01-17 |
| BE899876A (en) | 1984-12-10 |
| IT1179182B (en) | 1987-09-16 |
| SE8403093D0 (en) | 1984-06-08 |
| GB8412991D0 (en) | 1984-06-27 |
| FI841931A (en) | 1984-12-11 |
| NZ207888A (en) | 1987-11-27 |
| GB2141683A (en) | 1985-01-03 |
| GR81645B (en) | 1984-12-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |