FI74251B - SYSTEM FOER VARNING AOT PILOTEN FOER EN FARLIG FLYGPROFIL UNDER MANOEVRERING PAO LAOG HOEJD. - Google Patents

Description

1 74251 Driver alarm system for dangerous flight profile during low movements

The present invention relates generally to ground proximity warning systems, and in particular to a system according to the preamble of claim 1, which protects an airplane during low altitude movements if the airplane is to descend below a predetermined minimum altitude or if the airplane 10 exceeds a predetermined rate of descent. or other movements that require tilting. Clearly distinguishable, special warnings are issued to inform the pilot of a specific action to be taken to correct a dangerous flight profile.

15 Proximity warning systems are already known to warn the pilot of a dangerous flight profile. These systems provide warnings to the pilot of the airplane in a number of hazardous flight situations, such as when flying below a pre-determined minimum altitude of 20 and allowing the airplane to reach excessive rate of descent after take-off or approach. An example of a system that warns the pilot when he falls below a predetermined minimum desired altitude is a system that compares the radio altitude to the lowest decision altitude setting, or the "alarm.ys" setting on the radio altimeter, and provides an audible warning or a visual warning if below the minimum decision height. Examples of systems that provide a warning to the pilot during take-off or missed approach if the airplane sinks at an excessive rate of change of pressure altitude or loses a predetermined amount of pressure altitude are disclosed in U.S. Patent Nos. 3,946,358, 35 U.S. 3,947,808, U.S. 3,947,808, U.S. 3,947,808, U.S. Pat. , the applicant of which is the applicant of the present invention.

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Although these systems warn the pilot in the event that the airplane falls below a pre-set minimum altitude above the ground, or if the airplane falls too fast-5 ti after take-off or missed approach, they are primarily designed for commercial airplanes that do not normally fly at low altitudes or make turns or other difficult or violent movements near the ground. Thus, such systems do not normally provide sufficient warning to the pilot in very agile airplanes, such as fighter or ground combat aircraft, which perform tactical movements close to the ground.

It is therefore an object of the present invention to provide a warning system which overcomes many of the disadvantages of prior art warning systems during high speed and low flight operations.

It is a further object of the present invention to provide a warning system designed to provide a pilot of a high performance aircraft, such as a fighter or combat aircraft flying at low altitude, with a warning of a dangerous flight situation in sufficient time for him to take corrective action.

It is a further object of the present invention to provide the pilot of an aircraft performing turning and tilting movements near the ground with a warning of a dangerous situation, such as an excessive rate of descent, in sufficient time for the pilot to take corrective action.

It is a further object of the present invention to provide a warning of excessive radio altitude loss on take-off to take-off terrain.

35 The flight profile of a fighter or ground fighter aircraft includes low altitude 3 74251 flight and offensive parts, and if the pilot is disturbed or deviated from the direction, there is a risk of falling into the terrain by mistake or flying into slowly ascending terrain. The danger of flying in ascending terrain occurs primarily during take-off and during low-altitude cruising. The risk of inadvertent subsidence is greatest during low movements, which require large heeling angles such as those occurring during the attack part of the flight, because the pilot 10 can easily be disturbed and deviate from the direction during those movements, and because the aircraft tends to sink when flying at high heels.

The set objects are achieved by a warning system according to the invention, which is characterized by what is set forth in the characterizing part of claim 1.

Thus, according to a preferred embodiment of the invention, there is provided a warning system which measures the altitude of an airplane from the ground using a radio altimeter or the like and provides a special audible warning to the pilot, such as "TOO LOW", if the airplane sinks below a predetermined minimum altitude. during low-altitude cruising phases. A predetermined, desired minimum altitude is typically a minimum decision height that is manually set by a minimum decision height indicator or radio altimeter.

Thus, to provide a warning during takeoff in ascending terrain or during inadvertent descent before the minimum decision height 30 is reached, the system has a memory that monitors the radio altitude after takeoff and stores the maximum altitude reached after takeoff. In the event that the airplane falls below a predetermined portion of the maximum radio altitude reached before the minimum decision height of 35 is reached, a warning is also generated. This warning is typically the same "TOO LOW" warning that is generated if the minimum decision height is exceeded to indicate to the pilot that he is too low.

In addition, the system monitors the angle of inclination of the aircraft 5 and generates a second special warning in case the aircraft is below another predetermined altitude and exceeds a predetermined rate of descent that changes as a function of the angle of inclination of the aircraft to alert the pilot that the aircraft 10 is descending at excessive speed. during. The warning to be given should be unambiguous enough to allow the instructor to quickly identify the problem, and in the present embodiment a warning "ROLL OUT" or similar term is provided.

These and other objects and advantages of the present invention will become apparent upon consideration of the following detailed description and accompanying drawings, in which:

Figure 1 shows a logical block diagram of a warning system 20 according to the invention;

Figure 2 is a diagram illustrating the relationship between airspeed and radio altitude at which warnings are generated; and

Figure 3 is a diagram illustrating the relationship between the rate of change of pressure altitude 25 and the heeling angle required to generate a warning if an airplane sinks at excessive speed during a heeling motion.

Referring now to the drawings, and in particular to Figure 1, there is shown an embodiment of a proximity warning system 30 according to the invention which is particularly useful for providing warnings of unsafe flight situations during low flight, generally indicated by reference numeral 10. The system 10 of the invention is illustrated in Figure 35. in logical block diagram form as a series of gates, comparators, flip-flops and the like for illustrative purposes; however, it should be understood that the actual implementation of the logic may be different from that shown in Figure 1; with several digital and analog implementations, the signals used by the described warning system include radio altitude, pressure altitude change rate, airspeed, engine speed, aircraft tilt angle, minimum decision height, the position of the airplane landing gear as well as several qualification signals. Depending on the type of aircraft 10 in which the warning system is installed, the signals shown in Figure 1 can be obtained from individual gauges such as pressure altimeter 12, pressure altitude rate circuit 14, radio altimeter 16 and artificial horizon 18, and various discrete elements such as landings. discrete element indicating. These signals can also be obtained from the digital data bus on certain newer aircraft.

As previously discussed, the system of the present invention is designed to provide various warnings at various stages of aircraft operation. For example, the system is designed to provide a first warning, such as an aural or audible warning "TOO LOW", if the airplane sinks below mi-25 nominal altitude during a low voyage. This warning is also developed if the airplane loses the height of a predetermined section reached after take-off but before reaching the minimum decision height. In addition, the system is designed to provide a second, specific, special warning, such as an aural or audible "ROLL OUT" signal, if the aircraft sinks too quickly during a tilting motion. Thus, a logic circuit is provided to indicate to the system a particular flight phase in which the airplane 35 operates, e.g., take-off, low flight, or low motion 74251, so that an appropriate warning is generated when certain flight parameters are exceeded. This operation is provided by a logic circuit including AND gates 20, 22, 24, 26 and 28, an OR gate 30, a pair of set / reset flip-flops 32 5 and 34, a shift detector 36 and a switch 38 controlled by flip-flop 34.

Because the system is designed to provide warnings during take-off, low-altitude cruising, and low-altitude flight phases of flight, certain determinations must be made to determine if the airplane is actually in any of the above phases. The initial determinations are made by the AND gate 20, which provides an enable signal to the AND gates 22 and 24 only 15 if certain conditions are met. These conditions are that the wheels have no weight, indicating that the aircraft is actually flying, that the landing gear is up, and that the aircraft is not flying slower than 200 knots (375 km / h), thus indicating that the aircraft is not in landing gear.

In order for the system to function, the pressure altimeter 12, the pressure altitude change rate circuit 14 and the radio altimeter must also function properly. Thus, signals indicating that the altimeter and radio altimeter are not obstructed, as well as a signal indicating that the rate of change of radio altitude is not excessive, are input to gate 20 to allow gates 22 and 24 only if the altimeter 12, altitude change rate 14 circuit The signals obtained are valid.

30 In addition to determining whether an airplane is flying in a non-landing gear and whether the measuring equipment is operating correctly, it is necessary to determine whether the airplane is in the approach phase or in the take-off phase after take-off or missed approach. This determination is made by 35 AND gates 26 and 28, an OR gate 30 and a setting / reset flip-flop 32. In the embodiment shown, take-off or missed approach detour is indicated only if 74251 if both of the following conditions, take-off power and landing gear up, are met . If both conditions are met, the setting / reset flip-flop 32 is reset. The take-off power signals input to gate 26 may be obtained from a variety of sources, for example, a reference circuit that provides an enable signal to gate 26 when engine speed is high enough to indicate take-off power; or from a discrete element indicating the position of the power lever. An engine-10 engine tachometer indicating, for example, the speed of the jet engine supercharger zone 1 can be used to provide an engine speed signal, and a predetermined engine speed, e.g., 90% of the maximum engine speed, can be used to indicate take-off power. The landing gear up signal can be easily obtained from another discrete element, such as the switch operated by the landing gear or the landing gear operating lever in the cab.

The approach situation is indicated by gates 30 and 28, 20 when the landing gear is not up or the airplane is below 100 ft (30.5 m) altitude and the engine is not producing take-off power and the airplane speed is less than 200 knots (375 km / h). The approach indication from gate 28 sets the flip-flop 32.

25 In operation, during the take-off phase of the flight, the setting / reset flip-flop 32 is reset, thus causing the Q output of the flip-flop 32 to change from a high state to a low state. This displacement is indicated by a displacement detector 36 which generates an output pulse in response to the displacement and 30 sets a set / reset flip-flop 34. This causes the Q-output of flip-flop 34 to move switch 38 to the position shown in Figure 1, thus switching gate 22 to a single input circuit containing a comparator 40, a scaling circuit 42, and a radio altitude memory 44. These paths determine when the generator 46 should generate a "TOO LOW" signal during the take-off phase of the operation.

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When the airplane has completed its take-off, as evidenced by the fact that the radio altitude has exceeded the minimum decision altitude (MDA), the MDA comparator 50 generates a signal indicating 5 that the airplane has exceeded the minimum decision altitude to restore the flip-flop 34, thus resetting the flip-flop 34. When the flip-flop 34 is set, the switch 38 operates to separate the gate 22 from the low comparator 40 and switches the MDA comparator 50 less than the MDA output, thus making the system responsive to any sinking below the minimum decision height. Thus, when the airplane falls below the minimum decision height while in this state, the warning generator 46 generates a "TOO LOW" warning and feeds it to the converter 48.

15 As long as the airplane altitude is below a predetermined minimum decision height and a predetermined additional distance, such as 100 ft (30.5 m), but not below the minimum decision height, allows comparisons of 50 AND gates 24 more than MDA and less than 20 MDA + Using 100 ft signals input to its two inputs. Thus allowed, the AND gate 24 is made responsive to comparators 52 and 54 to operate a second warning generator 56 that generates a second warning, such as "ROLL OUT", when the rate of descent of the aircraft exceeds a predetermined level at a certain angle of inclination.

Looking at operation in more detail as the aircraft takes off, flip-flop 32 is reset, thus causing the shift detector 36 to provide an output pulse 30 to set flip-flop 34 to connect gate 22 to comparator 40. The output pulse from shift detector 36 also resets radio altitude memory to zero or (15.2 m). The radio altitude memory 35 receives altitude signals from the radio altitude meter 16, and maintains the maximum altitude 74251 reached after take-off. This maximum radio altitude value reached after take-off is fed to a scaling circuit which multiplies it by a scaling factor, for example 75%, and feeds it too low to a comparator 40 which controls the operation of the too low warning generator 46 during the take-off phase of operation.

The signal of the radio altimeter is also fed to the comparator 40 too low, and as long as the radio altitude remains above the maximum radio height multiplied by the scaling factor, no warning is generated. However, if the radio altitude falls below the scaled maximum altitude, e.g., 75% of the maximum altitude reached during flight, comparator 15 40 provides a signal to gate 22. This signal causes gate 22 to provide a signal to the "TOO LOW" warning generator 46 and causes generator 46 to generate a "TOO LOW". warning and input it either directly or indirectly to transducer 48, provided that gate 20 has allowed a second input of gate 22.

The radio altitude signal from the altimeter 16 is also input to the MDA comparator 50, which monitors the radio altitude signal from the radio altimeter 16 and provides a "GREATER THAN MDA" signal to flip-flop 34 when the ra-25 diode height exceeds the minimum decision height. This signal resets the flip-flop 34 and causes the switch 38 to connect the gate 22 to the MDA comparator 50 so that the MDA comparator 50 controls the generated warning. The MDA comparator 50 continues to monitor the radio altitude and no warning is triggered as long as the radio altitude remains above the minimum decision height. However, if the height falls below the minimum decision height and the gate 20 allows the gate 22, the MDA comparator provides a "LESS THAN MDA" signal to the gate 22 to cause the gate 22 to initiate a "TOO LOW" warning from the warning-generator 46.

When the airplane rises above the minimum decision height but remains below the minimum decision height and a predetermined additional distance, such as 100 feet (30.5 m), and as long as the gate 20 provides an allow level signal, the gate 24 has a tilt comparator 52 and a tilt angle comparator 54. under the guidance of. The function of the comparators 52 and 54 is to monitor the tilt angle and barometric rate of descent of the aircraft, and to cause the gate 24 to initiate a warning from the warning generator 56 if an unsafe combination of landing speed and tilt angle occurs.

10 As described above, the airplane tends to sink as the angle of inclination increases. However, this effort is not significant until the angle of inclination exceeds a predetermined level, such as 45 ° with a modern fighter or ground fighter aircraft, 15 such as the "Fairchild A10". Thus, the tilt angle comparator and 54 monitors the tilt angle signal generated by the artificial horizon 18, or a similar device that indicates the tilt angle of the aircraft and provides an enable signal to the gate 24 when the tilt angle reaches a value at which the aircraft tends to sink. This allows the generator 56 to generate a "ROLL OUT" warning if the barometric descent rate exceeds the maximum speed allowed for a particular tilt angle, as determined by the tilt comparator 52. The conditions required for the development of a "ROLL OUT" warning are further discussed in connection with the description in Figure 3.

Referring to Figure 2, which is a diagram illustrating the conditions required to generate a “TOO LOW” warning and to allow a “ROLL OUT” warning as a function of air-30 speed and altitude, these conditions are shown in two shaded areas in the diagram. neither warning can be generated as long as the airspeed of the aircraft is below a predetermined value, in this embodiment 200 35 knots (375 km / h) As long as the airspeed of the aircraft exceeds 200 knots (375 km / h) and the other above conditions are met, a "TOO LOW" warning is issued whenever 11 74251 the airplane sinks below the minimum decision height, or a predetermined percentage, for example, 75% of the maximum altitude reached during take-off or taxiing before exceeding the minimum decision height.

When the altitude of the airplane exceeds the minimum decision height but is below the minimum decision height plus a predetermined additional distance, such as 100 feet (30.5 m), a "ROLL OUT" warning is permitted.

10 However, the "ROLL OUT" warning is not automatically generated when the "ROLL OUT" warning border shown in Figure 2 is broken, as is the case with the "TOO LOW" warning border. The "ROLL OUT" warning mode is only allowed, but the actual warning is only generated 15 if the tilt angle exceeds a predetermined angle, e.g. 45 °, and if the descent rate breaks the edge of the descent rate curve (Figure 3) that determines the maximum allowable descent rate as a function of tilt angle.

The sink rate curve, which has been found to be particularly suitable for use in a fighter or ground plane, is shown in Figure 3. The shaded area shows the relationship between the heeling angle and the barometric sink rate required to generate a "ROLL OUT" 25 warning. As can be seen from Figure 3, the "ROLL OUT" warning is not generated until the tilt angle reaches 45 °, at which point the "ROLL OUT" warning is generated if the pressure altitude. the rate of descent exceeds 100 feet (30.5 m) per minute.

30 When the heeling angle has increased to 60 °, only a descent speed of 50 ft (15.2 m) per minute is required to initiate the warning, and when the heeling angle reaches 90 °, no sinking is acceptable, as the lift provided by the wings is practically zero.

Claims (18)

1 0 74251 for generating a second specific warning when the aircraft angle of incidence exceeds 45 degrees. An alert system for alerting an aircraft pilot to a hazardous flight condition during actuation 5 at low altitude, which system comprises a first signal device (16) for monitoring the aircraft's altitude above the ground surface and for generating signals corresponding to the aircraft's altitude above the ground, and a recording device (44) for recording an indication of a maximum altitude 10 above the ground surface which the aircraft night during the flight, characterized in that it comprises a) a device for selecting a desired minimum flight height above the ground surface, b) a terrain warning device (22,38,40,50) which responds to signals corresponding to the altitude above ground level and to the recording device (44), to generate a first specific warning as a function of the minimum flight altitude selector device, if the aircraft has exceeded a predetermined desired minimum flight altitude , and as a function of an in-flight maximum altitude above ground level, if the aircraft has not exceeded a previous desired flight altitude. Warning system according to claim 1, wherein the aircraft comprises a retractable landing gear, characterized in that it comprises a second signal device for generating signals corresponding to the power of the engine, a third signal device for generating signals corresponding to the position of the landing gear, a first clearance device (26). , 32,36,34) to operate the warning device for generating a warning if the landing site is up and the engine is operating at takeoff power or above it. 3. A warning system according to claim 1, characterized in that it comprises a second warning device (24,52,56) for generating a warning which in function of the aircraft's angle of incidence and sinking speed when the aircraft has exceeded a predetermined desired minimum flight altitude. Warning system according to claim 3, characterized in that it comprises other release devices (54) for releasing a device for generating a second specific warning only when the angle of incidence exceeds a predetermined value. Warning system according to claim 1, characterized in that the device (22,38,40,50) for generating a first warning is activated if the altitude drops below a desired minimum flight altitude after the aircraft has exceeded a predetermined desired altitude. Warning system according to claim 3, characterized in that it comprises a fourth signal device for generating a signal representing the angle of incidence of the aircraft, and a fifth signal device for generating a signal representing the sinking velocity of the aircraft 20. Warning system according to claim 6, characterized in that it comprises devices (20) for preventing the generation of a warning in the event that the aircraft's sinking speed exceeds a predetermined second value. Warning system according to claim 1, characterized in that a first specific warning is activated if the signal corresponding to the altitude above the ground surface drops below a predetermined proportion of the maximum altitude reached after takeoff, if the aircraft has not yet exceeded a predetermined desired mimin flight altitude. 9. Warning system according to claim 1, characterized in that the minimum flight height is manually adjusted. Warning system according to claim 4, characterized in that the system is activated __ _— T— __ Warning system according to claim 8, characterized in that the predetermined proportion 5 of the highest reached altitude is 75% of the altitude reached above the surface. The warning system according to claim 6, characterized in that it comprises a second free device (54) for releasing a warning device 10 (24,52,56) for generating a second specific warning, if the aircraft operates under a second flight altitude and above for a desired minimum flight altitude. A warning system according to claim 4, characterized in that the warning is generated when the incident angle exceeds 45 degrees and the sinking speed exceeds 30 m / min (100 feet / min). Warning system according to claim 4, characterized in that the warning is generated when the angle of incidence exceeds 60 degrees and the sinking speed 20 exceeds 15 m / min (50 feet / min). 15. A warning system according to claim 4, characterized in that the warning is generated when the angle of incidence exceeds 90 degrees and the sinking speed exceeds 0 m / min. 16. A warning system according to claim 4, characterized in that the value of the predetermined drop rate is an inverse function of the angle of incidence. The warning system according to claim 3, characterized in that it comprises a third release device (20) for releasing the first and second specific warning devices only where the flight speed exceeds a certain value. The warning system according to claim 6, characterized in that it comprises a device 35 (20) which responds to the aircraft's speed for retaining the warning generation when the aircraft speed exceeds a predetermined speed.