Abstract:
A system and method for intervention control of an aircraft in the event of pilot command error whether voluntary or involuntary. Impending detection of a chaotic condition associated with a maneuvering aircraft enable early prediction and control of the aircraft where solutions based upon performance prediction are available. A further feature of the present intervention control of the aircraft enables an equipment malfunction detection signal substitution of a satisfactory equipment signal.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a flight safety system and more particularly to a method and apparatus for preventing accidents resulting from pilot command errors or equipment malfunctions during the flight of an aircraft. 
     2. Description of the Prior Art 
     Heretofore, alarm systems have sounded to indicate that a major problem has occurred on the aircraft that the flight crew must attend to immediately, e.g.: 
     a. The aircraft&#39;s speed has exceeded a predetermined safe mach level, e.g. 0.86 mach. 
     b. Cabin pressure has fallen below acceptable levels. 
     c. The autopilot has become disconnected for reasons other than pilot command. 
     d. Fire indication. 
     e. Improper take-off or landing configurations. 
     Heretofore, the pilot of the aircraft has been depended upon to respond to events a. through e. 
     Prior systems failures aboard the aircraft such as failure of the instrument landing system, automatic braking system, autopilot etc. have heretofore afforded the pilot of the aircraft no known remedy except to fly the aircraft with such systems inoperative. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides support services for equipment aboard an aircraft normally heretofore available only at a ground service facility. 
     Input signals from equipment aboard the aircraft are coupled via a data link to corresponding ground equipment continuously maintained as a standard by e.g. the manufacturer. An equipment substitution signal commands an output signal from the ground equipment standard to be substituted for the equipment output signal aboard the aircraft. The output signal transmitted from the ground equipment is an information signal transmitted over a data link reconditioned as required to the proper signal level required by the equipment aboard the aircraft. An equipment substitution signal is generated in response to comparison of the aircraft equipment signal with the standard. 
     Failure of airborne equipment does not result in loss of this equipment during flight thus handicapping the pilot in flight of the aircraft. 
     A further important feature of the system of the present invention is the provision for override of pilot control when a pilot command error is detected. A pilot command error may occur when an incorrect flight configuration and operating parameters are detected whether voluntary or involuntary. The present system provides immediate override should this be necessary in the event of pilot inability to respond through immediate voice communication where time permits. The present ground system override permits a pilot at the ground station through activated ground controls corresponding to the aircraft&#39;s flight controls to fly the aircraft. The pilot in command at the ground station may, instead of controlling the flight of the aircraft manually, utilize a flight control computer containing further flight control programming not available to the pilot flight control computer, e.g. containing programs for flying the aircraft in rarely occurring emergency situations such as loss of a functioning control surface where immediate control signals are required in response to uncontrolled maneuvering of the aircraft which control signals are based upon understanding and calculations of flow physics. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a block diagram of an embodiment of the present system showing an aircraft under control of the present intervention control system and a further aircraft transparent to the present intervention control system; 
     FIG. 2 is exemplary of a comparator circuit utilized in the present intervention control system of FIG. 1 for a twin engine commercial jet aircraft providing automatic back up in the event of a pilot error; 
     FIG. 3 is illustrative of the present system ground equipment substitution in the event of the presence of an equipment substitution signal representative of a corresponding equipment failure aboard an aircraft; 
     FIG. 4 is a diagram illustrative of normal configurations at different altitudes utilized under normal conditions; and, 
     FIG. 5 is illustrative of an exemplary type of flight control system for flight control based upon input flight control signal information received from an aircraft data link to a ground station which information signals are representative of abnormal maneuver of an aircraft during an emergency condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Introduction 
     Transmission of digital data between each commercial aircraft and the proper airline flight operations department occurs today through ACARS (Aircraft Addressing and Reporting System) developed by ARINC (Aeronautical Radio Inc.). Such data presently includes aircraft identification, fuel data, engine performance data, etc. Development of broadband communications between aircraft, in flight satellite communications links, H.F. (high frequency) links, etc. are expanding the potential for increased data transfer and will reduce the need for an extensive network of ground stations. These efforts at improving data transfer rates will facilitate increased use of systems such as hereinafter described. Close monitoring of aircraft performance and control of the aircraft under emergency conditions based upon early data as hereinafter described will increase the probability of recovery under such conditions. Improved support functions for aircraft in flight will result from early detection of equipment malfunction and replacement of corrected output signals for the malfunctioning equipment. 
     Turning now to the system of FIG. 1, there is shown an aircraft B having a flight control system  20  which includes a flight control computer which interfaces with a number of aircraft systems, various aircraft sensors, e.g. aileron position sensor, rudder position sensor, flap position sensors etc. Also as known in the art, the flight control computer connects to aircraft instrumentation as well as aircraft autopilot servos for actuating and controlling the aircraft aileron, rudder, flaps, spoilers etc. Flight control systems including a flight control computer are well known as shown e.g. in U.S. Pat. No. 5,714,948, the details of which are incorporated herein by reference. 
     Aircraft A also includes a flight control system  20  as hereinbefore described and shown in aircraft B. Remote control of aircraft commenced with hobbyists and later more sophisticated remote control systems appeared in the patent literature e.g. as shown in U.S. Pat. Nos. 5,067,674 and 3,557,304. U.S. Pat. No. 3,3557,304 is illustrative of a system where a cockpit T.V. camera  11  provides a display  16  of panel instruments  22  at the ground station for control of the aircraft. The above remote control system of U.S. Pat. No. 3,557,304 is incorporated herein by reference and is useful in controlling the flight of aircraft A or aircraft B under conditions unique to the present system only where comparator  40  is actively controlling aircraft A in a manner hereinafter described. Aircraft B is not under remote control and is transparent to remote ground control since comparator  40  in aircraft B has not detected a pilot command error signal thereby activating transmitter-receiver  50 . 
     Turning now to FIG. 2 illustrative of comparator circuit  40  there are seen aircraft instrument data information signals, signal  29  representative of aircraft speed and a further signal  30  representative of a 2 engine OFF condition for a twin engine commercial jet aircraft. As shown in comparator circuit  40  of FIG. 2, when signal  29  representative of aircraft speed exceeds 0.86 mach AND a signal  30  representative of a 2 engine OFF condition are provided as inputs to comparator circuit  40 , then a pilot command error signal is provided by AND circuit  98 . Pilot command error signal  117  drives a relay closing switches  229  and  230  activating transmitter-receiver  50  and providing data transfer  25  through data link  52  to ground station transmitter-receiver  60  for remote control of aircraft A. While comparator  40  with the aforementioned input signals  29  and  30  as shown in FIG. 2 for a twin engine commercial jet aircraft clearly illustrate immediate generation of a pilot command error signal  117  and need for instant remote control by a ground station to avoid a potentially catastrophic incident, it will be recognized by those skilled in the art from the foregoing that other combinations of flight data indicative of incipient need for generation of a pilot command error signal  117  and ground control will become apparent e.g. a pair of input signals such as the combination of low cabin temperature representative of the approach of dangerous interior icing AND an ON autopilot would necessitate ground control. In the above example of pilot command error it is important to observe that pilot command error signal  117  is generated at the instant that the twin engine OFF signal appears as an input to comparator  40  together with an aircraft speed signal exceeding 0.86 mach, thus transferring control to the ground control and thereby enabling recovery action to be taken before the occurrence of further abnormal maneuvering of the aircraft. A further example would be the combination during final descent of signal representative of a flight path angle exceeding the flight path angle for the runway and a signal representative of pull up commands from the aircraft&#39;s proximity warning system. 
     Turning now to FIG. 3 there is seen a flight control system  41  aboard an aircraft in flight and there is also seen an identical flight control system  42  which is located at a ground station and is tested as a standard frequently by ground personnel from the manufacturer of these flight control systems. Flight control system  41  aboard the aircraft in flight and the counterpart standard flight control system  42  at the ground station here are shown in U.S. Pat. No. 3,327,973 and taken for illustrative purposes only since different types of flight control systems for various aircraft will require their matching ground station counterpart for generation of an equipment substitution signal  224  in the system of FIG.  3 . Transmitter-receiver  50  aboard an aircraft and transmitter-receiver  60  at the ground station in FIG. 3 correspond to transmitter-receiver  50  aboard aircraft A and transmitter-receiver  60  at the ground station in FIG. 1. A comparator circuit  140  as shown in FIG. 3 looks at output signal  24  of flight control system  41  aboard the aircraft (transmitted through data link  52 ) and compares the output signal  24  with output signal  124  from standard ground control flight control system  140  and if there is inequality causes equipment malfunction detection signal  224  to be transmitted via data link  52  to energize switch  516  to the dotted line position thereby transmitting standard flight control output signal  124 , to autopilot elevator control of the aircraft in substitution of the flight control output signal  24  from the malfunctioning aircraft equipment. It should be noted that ground flight control system  42  receives the identical input signals via data link  52  as flight control system  41  aboard the aircraft. 
     While generation of an equipment malfunction detection signal for an aircraft flight control system has been described, it will be recognized by those skilled in the art that other systems aboard the aircraft may be checked either continuously or periodically with a manufacturers ground system standard depending upon the data communication channel characteristics available including bandwidth, data transfer rates and number of aircraft monitored for equipment malfunctions by the present system. 
     Turning now to FIG. 4, it can be seen that aircraft during flight experience several configurations including cruise configuration, pre landing configuration and transition configurations prior to achieving a pre landing configuration. 
     Hereinbefore described was the generation of a pilot command error signal  107  based upon recognized known conditions requiring immediate remote control from a ground station however predicting aircraft behavior and providing aircraft control of maneuvering aircraft due to various possible equipment and/or aircraft control surface failures is beyond the capability of even an experienced pilot under most circumstances since these are rare occurrences. Behavior of an aircraft under such conditions requires wind tunnel testing, analytical and computational studies for each of a number of single or combinations of abnormal configuration flight conditions. Unsteady forces, moments, surface pressures etc. all have to be studied to provide correct controls under such circumstances. Occurrences of undesired events such as stall below glide slope capture in a pre landing configuration allow minimal opportunity for correction and the system of FIG. 5 in contrast is in general directed to recoveries at higher altitudes from abnormal maneuvering configurations based upon analysis of non-linear aerodynamics. The system of FIG. 5 inputs flight control information signals from an aircraft via data link  52  to a control computer  121  at the ground station which provides output signals to ground flight control  17  for transmission of flight control signals  28  to control the aircraft in flight instead of utilization of ground control computer  21  hereinbefore discussed for control under normal flight. Of importance is the immediate and early detection of flight control information signals representative of abnormal maneuvering so that control computer  21  can provide immediate flight control signals  28  for corrective action prior to time lapse and further deterioration of flight control of the aircraft.