Patent Description:
In various scenarios, a pilot may take over operational control of an aircraft and deviate from a planned flight path. An example of such system is disclosed in <CIT>. Often, this is initiated by an air traffic control (ATC) command. During this manual operation, one or more interrupts could occur that indicate a need to exit the manual mode, put the aircraft in an automatic flight control mode, and return the aircraft to the planned flight path.

The referenced interrupts are events that trigger or indicate a need to exit the manual mode. The referenced interrupts can be categorized as obstacles, an equipment or fuel level issue, and a pilot health issue. Responsive to the interrupt, control must be switched from manual control to a guided control and it must be determined where best to rejoin the planned flight path. In addition to determining where, it must be determined how to rejoin the planned flight path. The where and how inform a desired recapture path. Determining the details of the recapture path is a technical problem. While available flight guidance systems provide useful information, enhanced flight guidance systems that provide technologically improved recapture path assistance are desired.

Accordingly, enhanced flight guidance systems and methods are desired. The desired enhanced flight guidance systems and methods respond to an interrupt received while in manual operation by integrating relevant information to strategically compute a recapture path, including predicting aircraft state data, and generating guidance controls along the recapture path. Technical effects of the desired system include the timely generation of the strategically computed recapture path for immediate and automatic execution (i.e., exiting the manual mode and taking control of aircraft operation). The following disclosure provides these technological enhancements, in addition to addressing related issues.

The invention concerns a flight guidance system for an aircraft as set out in appended independent claim <NUM>.

The invention concerns a method for flight guidance as set out in appended independent claim <NUM>.

Preferred embodiments of the system and method are provided as set out in the appended dependent claims.

Furthermore, other desirable features and characteristics of the system and method will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the preceding background.

The present application will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:.

The embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention that is defined by the claims.

As mentioned, there is continued desire for enhanced flight guidance systems that determine when to retake control (i.e., switch from manual operation to flight controlled operation of the aircraft) and how to rejoin a planned flight plan. The provided enhanced flight guidance system can respond to a variety of interrupts that may occur while the aircraft is being operated in a manual mode. As mentioned, the interrupts may be categorized as an obstacle, equipment/fuel, or pilot health monitor interrupt. Examples of obstacle interrupts include terrain and weather hazards. Equipment/fuel interrupts are sourced from onboard systems, generally as an aspect of aircraft state data, described below. The pilot health monitor may generate an interrupt indicating a medical issue with the pilot. The provided enhanced flight guidance system responds to the interrupt by evaluating a plurality of relevant factors and selecting an appropriate recapture path strategy to thereby generate a customized recapture path that includes the associated guidance controls sufficient to take back control of the aircraft and to smoothly return the aircraft to its planned flight path. Provided enhancements over conventional flight guidance systems include:.

Exemplary embodiments process and integrate inputs using novel rules and algorithms to convert them into enhanced flight guidance that can be automatically implemented and can be displayed on an aircraft display system. The figures and descriptions below provide more detail.

Turning now to <FIG>, in an embodiment, enhanced flight guidance system <NUM> for generating a recapture path (also referred to herein as "system" <NUM>) is generally associated with a mobile platform <NUM>. In various embodiments, the mobile platform <NUM> is an aircraft, and is referred to as aircraft <NUM>. The system <NUM> embodies the control module <NUM>. In some embodiments, the control module <NUM> may be integrated within a preexisting mobile platform management system, avionics system, cockpit display system (CDS), flight controls system (FCS), or aircraft flight management system (FMS). Although the control module <NUM> is shown as an independent functional block, onboard the aircraft <NUM>, in other embodiments, it may exist in an electronic flight bag (EFB) or portable electronic device (PED), such as a tablet, cellular phone, or the like. In embodiments in which the control module is within an EFB or a PED, a display system <NUM> and user input device <NUM> may also be part of the EFB or PED.

The control module <NUM> may be operationally coupled to any combination of the following aircraft systems: a communication system and fabric <NUM>; a source of a planned/intended flight plan <NUM> (including a planned flight path with a stabilized approach) such as a navigation database (NavDB); a source of real-time aircraft navigation data <NUM>, such as a navigation system; a source of aircraft state data <NUM>; a source of weather information <NUM> (current, predicted, or current and predicted) a source of terrain data <NUM>; and, a source of air traffic control (ATC <NUM>) commands. Additionally, the system <NUM> may include a display system <NUM>; a user input device <NUM>; and, a pilot health monitor <NUM>. The functions of these aircraft systems, and their interaction, are described in more detail below.

Real-time aircraft navigation data may include any of: an instantaneous location (e.g., the latitude, longitude, orientation), an instantaneous heading (i.e., the direction the aircraft is traveling in relative to some reference), a flight path angle, a vertical speed, a ground speed, an instantaneous altitude (or height above ground level), and a current phase of flight of the aircraft <NUM>. As used herein, "real-time" is interchangeable with current and instantaneous. In some embodiments, the real-time aircraft navigation data is generated by a navigation system. The navigation system may be realized as including a global positioning system (GPS), inertial reference system (IRS), or a radio-based navigation system (e.g., VHF omni-directional radio range (VOR) or long-range aid to navigation (LORAN)), and may include one or more navigational radios or other sensors suitably configured to support operation of the FMS, as will be appreciated in the art. The aircraft navigation data is made available, generally by way of the communication system and fabric <NUM>, so other components, such as the control module <NUM> and the display system <NUM>, may further process and/or handle the aircraft state data.

An intended/planned flight plan (FP) may include a planned flight path made up of a series of intended geospatial midpoints between a departure and an arrival. In some embodiments, the geospatial midpoints are called waypoints. The connections between each of the geospatial midpoints may be referred to as a "leg," and each geospatial midpoint and leg of the flight path have performance data associated therewith (non-limiting examples of the performance data include intended navigation data, such as: intended airspeed, intended altitude, intended acceleration, intended flight path angle, and the like). In various embodiments, the planned flight path may be part of an operational flight plan (OFP). A source of the intended flight path <NUM> may be a storage location or a user input device. In various embodiments, a navigation database, NavDB, is the source of the active trajectory or OFP. The NavDB is generally a storage location that may also maintain a database of flight plans, and/or information regarding terrain and airports and/or other potential landing locations (or destinations) for the aircraft <NUM>.

The source of aircraft state data <NUM> generally provides, for each of a variety of aircraft <NUM> subsystems, current status/state and performance data. Examples of aircraft state data include: a flight mode, an engine status, an engine thrust level, a fuel level, a flap configuration, a braking status, a temperature control system status, and the like. As may be appreciated, the source of aircraft state data <NUM> may therefore include a variety of components, such as on-board detection sensors, which may be operationally coupled to the control module <NUM>, central management computer, or FMS.

In various embodiments, a communications system and fabric <NUM> is configured to support instantaneous (i.e., real time or current) communications between on-board systems (i.e., the source of the intended flight path <NUM>, the source of aircraft navigation data <NUM>, the source of aircraft state data <NUM>, the display system <NUM>, and the source of terrain data <NUM>), the control module <NUM>, and the one or more external data source(s), such as the source of weather information <NUM>, the air traffic control <NUM>. As a functional block, the communications system and fabric <NUM> represents one or more transmitters, receivers, and the supporting communications hardware and software required for components of the system <NUM> to communicate as described herein. In various embodiments, the communications system and fabric <NUM> may implement additional communications not directly relied upon herein, such as bidirectional pilot-to-ATC (air traffic control) communications via a datalink; support for an automatic dependent surveillance broadcast system (ADS-B); a communication management function (CMF) uplink; a terminal wireless local area network (LAN) unit (TWLU); an instrument landing system (ILS); and, any other suitable radio communication system that supports communications between the aircraft <NUM> and the various external source(s). In various embodiments, the control module <NUM> and communications system and fabric <NUM> also support the herein referenced controller pilot data link communications (CPDLC), such as through an aircraft communication addressing and reporting system (ACARS) router; in various embodiments, this feature may be referred to as a communications management unit (CMU) or communications management function (CMF). In summary, the communications system and fabric <NUM> may allow the aircraft <NUM> and the control module <NUM> to receive information that would otherwise be unavailable to the pilot and/or co-pilot using only the onboard systems.

The source of weather information <NUM> may include weather radar, a source for meteorological terminal aviation weather reports (METARS), and the like. The weather information is generally organized as a plurality (N) of regions, each region having an associated weather pattern, and each weather pattern having a corresponding severity rating, for example, high (also referred to as severe), moderate, low (also referred to as minor), and none. The severity rating is the one defined by the Federal Aviation Administration related to weather radar. The weather information may be organized in this manner before being transmitted onboard the aircraft <NUM> or may be organized this way by the control module <NUM> prior to further processing described below. In some embodiments, the source of weather information <NUM> is external to the aircraft <NUM>, and in other embodiments, the source of weather information <NUM> is on-board the aircraft <NUM>.

The source of terrain data <NUM> may be a database located on or off-board the platform <NUM>. Air traffic control (ATC) <NUM> communicates wirelessly with the system <NUM>. The pilot health monitor <NUM> may provide interrupts and information as a function of information from biometric sensors associated with the pilot. For example, the pilot health monitor may generate interrupts that indicate pilot unconsciousness or other medical conditions such as illness, cardiac instability, and drowsiness. The user input device <NUM> and the control module <NUM> are cooperatively configured to allow a user (e.g., a pilot, co-pilot, or crew member) to interact with display devices <NUM> in the display system <NUM> and/or other elements of the system <NUM>, as described in greater detail below. Depending on the embodiment, the user input device <NUM> may be realized as a cursor control device (CCD), keypad, touchpad, keyboard, mouse, touch panel (or touchscreen), joystick, knob, line select key, voice controller, gesture controller, or another suitable device adapted to receive input from a user. When the user input device <NUM> is configured as a touchpad or touchscreen, it may be integrated with the display system <NUM>. As used herein, the user input device <NUM> may be used by a pilot to communicate with external sources, such as ATC, to modify or upload the program product <NUM>, etc. In various embodiments, the display system <NUM> and user input device <NUM> are onboard the aircraft <NUM> and are also operationally coupled to the communication system and fabric <NUM>. In some embodiments, the control module <NUM>, user input device <NUM>, and display system <NUM> are configured as a control display unit (CDU).

In various embodiments, the control module <NUM>, alone, or as part of a central management computer (CMS) or a flight management system (FMS), draws upon data and information from the source of intended flight path <NUM> and source of aircraft navigation data <NUM> to provide real-time flight guidance for aircraft <NUM>. The real time flight guidance may be provided to a user by way of images <NUM> on the display system <NUM>, audible emissions from an audio system, or the like. For example, the control module <NUM> may compare an instantaneous position and heading of the aircraft <NUM> with planned flight plan data for the aircraft <NUM> and generate display commands to render images <NUM> showing these features and distinguishing them from each other. The control module <NUM> may further provide flight guidance responsive to associating a respective airport, its geographic location, runways (and their respective orientations and/or directions), instrument procedures (e.g., approach procedures, arrival routes and procedures, takeoff procedures, and the like), airspace restrictions, and/or other information or attributes associated with the respective airport (e.g., widths and/or weight limits of taxi paths, the type of surface of the runways or taxi path, and the like) with the instantaneous position and heading of the aircraft <NUM> and/or with the planned flight plan for the aircraft <NUM>.

The control module <NUM> may perform display processing. In various embodiments, the control module <NUM> generates display commands for the display system <NUM> to cause the display device <NUM> to render thereon the image <NUM>, comprising various graphical user interface elements, tables, icons, alerts, menus, buttons, and pictorial images, as described herein. The display system <NUM> is configured to continuously receive and process the display commands from the control module <NUM>. The display system <NUM> includes a display device <NUM> for presenting an image <NUM>. In various embodiments described herein, the display system <NUM> includes a synthetic vision system (SVS), and the image <NUM> is a SVS image. In exemplary embodiments, the display device <NUM> is realized on one or more electronic display devices, such as a multi-function display (MFD) or a multi-function control display unit (MCDU), configured as any combination of: a head up display (HUD), an alphanumeric display, a vertical situation display (VSD) and a lateral navigation display (ND).

The control module <NUM> may perform graphical processing. Responsive to display commands, renderings on the display system <NUM> may be processed by a graphics system, components of which may be integrated into the display system <NUM> and/or be integrated within the control module <NUM>. Display methods include various types of computer generated symbols, text, and graphic information representing, for example, pitch, heading, flight path, airspeed, altitude, runway information, waypoints, targets, obstacles, terrain, and required navigation performance (RNP) data in an integrated, multi-color or monochrome form. Display methods also include various formatting techniques for visually distinguishing objects and routes from among other similar objects and routes. The control module <NUM> may be said to display various images and selectable options described herein. In practice, this may mean that the control module <NUM> generates display commands, and, responsive to receiving the display commands from the control module <NUM>, the display system <NUM> displays, renders, or otherwise visually conveys on the display device <NUM>, the graphical images associated with operation of the aircraft <NUM>, and specifically, the graphical images as directed by the control module <NUM>. In various embodiments, any combination of the control module <NUM>, user input device <NUM>, source of aircraft state data <NUM>, and communication system and fabric <NUM>, may be coupled to the display system <NUM> such that the display system <NUM> may additionally generate or render, on the display device <NUM>, real-time information associated with respective aircraft <NUM> systems and components.

The control module <NUM> performs the functions of the system <NUM>. As used herein, the term "module" refers to any means for facilitating communications and/or interaction between the elements of the system <NUM> and performing additional processes, tasks and/or functions to support operation of the system <NUM>, as described herein. In various embodiments, the control module <NUM> may be any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination. Depending on the embodiment, the control module <NUM> may be implemented or realized with a general purpose processor (shared, dedicated, or group) controller, microprocessor, or microcontroller, and memory that executes one or more software or firmware programs; a content addressable memory; a digital signal processor; an application specific integrated circuit (ASIC), a field programmable gate array (FPGA); any suitable programmable logic device; combinational logic circuit including discrete gates or transistor logic; discrete hardware components and memory devices; and/or any combination thereof, designed to perform the functions described herein.

Accordingly, in <FIG>, an embodiment of the control module <NUM> is depicted as comprising a processor <NUM> and a memory <NUM>. The processor <NUM> may comprise any type of processor or multiple processors, single integrated circuits such as a microprocessor, or any suitable number of integrated circuit devices and/or circuit boards working in cooperation to carry out the described operations, tasks, and functions by manipulating electrical signals representing data bits at memory locations in the system memory, as well as other processing of signals. The memory <NUM> may comprise RAM memory, ROM memory, flash memory, registers, a hard disk, or another suitable non-transitory short or long-term storage media capable of storing computer-executable programming instructions or other data for execution. The memory <NUM> may be located on and/or co-located on the same computer chip as the processor <NUM>. Generally, the memory <NUM> maintains data bits and may be utilized by the processor <NUM> as storage and/or a scratch pad during operation. Specifically, the memory <NUM> stores instructions and applications <NUM>. Information in the memory <NUM> may be organized and/or imported from an external source <NUM> during an initialization step of a process; it may also be programmed via a user input device <NUM>.

During operation, the processor <NUM> loads and executes one or more programs, algorithms and rules embodied as instructions and applications <NUM> contained within the memory <NUM> and, as such, controls the general operation of the control module <NUM> as well as the system <NUM>. The novel recapture path program <NUM> includes rules and instructions which, when executed by the processor <NUM>, convert the processor <NUM>/memory <NUM> configuration into the recapture path control module <NUM>, which is a novel and enhanced flight guidance control module that performs the functions, techniques, and processing tasks associated with the operation of the enhanced flight guidance system <NUM> for generating a recapture path. Novel program <NUM> and associated stored variables <NUM> may be stored in a functional form on computer readable media, for example, as depicted, in memory <NUM>. While the depicted exemplary embodiment of the control module <NUM> is described in the context of a fully functioning computer system, those skilled in the art will recognize that the mechanisms of the present disclosure are capable of being distributed as a program product <NUM>.

As a program product <NUM>, one or more types of non-transitory computer-readable signal bearing media may be used to store and distribute the program <NUM>, such as a non-transitory computer readable medium bearing the program <NUM> and containing therein additional computer instructions for causing a computer processor (such as the processor <NUM>) to load and execute the recapture path program <NUM>. Such a program product <NUM> may take a variety of forms, and the present disclosure applies equally regardless of the type of computer-readable signal bearing media used to carry out the distribution. Examples of signal bearing media include: recordable media such as floppy disks, hard drives, memory cards and optical disks, and transmission media such as digital and analog communication links. It will be appreciated that cloud-based storage and/or other techniques may also be utilized as memory <NUM> and as program product time-based viewing of clearance requests in certain embodiments.

In various embodiments, the processor/memory unit of the control module <NUM> may be communicatively coupled (via a bus <NUM>) to an input/output (I/O) interface <NUM>, and a database <NUM>. The bus <NUM> serves to transmit programs, data, status and other information or signals between the various components of the control module <NUM>. The bus <NUM> can be any suitable physical or logical means of connecting computer systems and components. This includes, but is not limited to, direct hard-wired connections, fiber optics, infrared and wireless bus technologies.

The I/O interface <NUM> enables intra control module <NUM> communication, as well as communications between the control module <NUM> and other system <NUM> components, and between the control module <NUM> and the external data sources via the communication system and fabric <NUM>. The I/O interface <NUM> may include one or more network interfaces and can be implemented using any suitable method and apparatus. In various embodiments, the I/O interface <NUM> is configured to support communication from an external system driver and/or another computer system. In one embodiment, the I/O interface <NUM> is integrated with the communication system and fabric <NUM> and obtains data from external data source(s) directly. Also, in various embodiments, the I/O interface <NUM> may support communication with technicians, and/or one or more storage interfaces for direct connection to storage apparatuses, such as the database <NUM>.

In some embodiments, the database <NUM> is part of the memory <NUM>. In various embodiments, the database <NUM> and the source of terrain data, such as database <NUM> are integrated, either within the control module <NUM> or external to it. Additionally, in some embodiments, the source of terrain data <NUM> includes airport features data, and both the airport features data and terrain data are pre-loaded, and internal, to the control module <NUM>.

The novel control module <NUM> may perform, responsive to an interrupt, the functions of generating a recapture path and generating associated guidance controls for various geospatial midpoints along the recapture path, each as a function of aircraft structures, systems, and performance. The processor <NUM> loads the instructions embodied in the program <NUM>, thereby being programmed with program <NUM>. When programmed with program <NUM>, the processor <NUM> executes program <NUM>, and the processor <NUM>, the memory <NUM>, and the database DB <NUM> form the novel enhanced flight guidance system <NUM>.

First, the control module <NUM> recognizes the co-occurrence of an active flight path different than the planned flight path when the aircraft is being operated in manual mode. While in this co-occurrence scenario, the control module <NUM> receives an interrupt. Upon receiving an interrupt, the interrupt is categorized as an obstacle, according to the invention, and used in the determination of a recapture path strategy.

In various embodiments, the recapture path strategy may also be selected as a function of flight state, such as: the phase of flight, the current flight area and/or airspace, a current or target flight procedure, and relevant guidance (GUID) targets. In various embodiments, the recapture path strategy may also be selected as a function of the aircraft <NUM> state, such as current altitude, speed, heading, engine performance, aircraft gross weight (GW), and aircraft fuel level or fuel on board (FOB). In various embodiments, the recapture path strategy may also be selected based on potential aircraft roll, pitch, and yaw, as well as related comfort specifications. In an example, the shortest recapture path may have to be balanced against roll information, particularly when the phase of flight is a final approach, as in <FIG>, below.

The control module <NUM> selects a recapture path strategy from among lateral, vertical, and mixed lateral and vertical. Lateral recapture path strategies are generated, at least in part, as a function of the current location and heading of the aircraft <NUM> with respect to the geospatial midpoints constituting the planned flight path. According to the invention the selected recapture path strategy is that of a mixed lateral and vertical. <FIG> are directed to lateral recapture path strategies. In <FIG> and <FIG>, vertical and mixed lateral and vertical recapture path strategies are described.

<FIG> is a simplified image depicting several recapture strategies for when there is an obstacle to the shortest recapture path back to the planned flight path, in accordance with an exemplary embodiment. The planned flight path <NUM> is described by geospatial midpoints <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, which are connected in series in the direction of travel of the aircraft <NUM>. Aircraft <NUM> is on an active flight path (i.e., current flight path) with a heading <NUM>. Therefore, the current flight path is not the planned flight path <NUM>. The control module recognizes the cooccurrence of this scenario and the aircraft <NUM> being operated in manual mode. At a point on a trajectory defined by the current heading of aircraft <NUM>, an interrupt <NUM> is received. Responsive to the interrupt <NUM>, the system <NUM> begins a managed mode to retake control of the aircraft operation from manual mode. While in the managed mode, it employs one or more recapture path strategies to compute and evaluate a respective one or more potential recapture paths for the aircraft <NUM> to return to the planned flight path <NUM>. As used herein, "recapture paths for the aircraft <NUM> to rejoin the planned flight path" is shortened to "recapture path"). Recapture strategies described herein can be prepared in advance while being in manual mode; and then, upon transition to managed mode, the processor can evaluate which one is the best, to provide a faster response of the system. An obstacle <NUM>, such as a weather hazard, terrain, or other object, is between the trajectory defined by the current heading <NUM> of aircraft <NUM> and the planned flight path <NUM>; accordingly, at least one of the strategies for generating a recapture path includes processing information detailing the obstacle. In the example, a shortest recapture path <NUM>, goes right through the obstacle <NUM>. A recapture path <NUM> is generated that has the shortest distance to the planned flight path while avoiding the obstacle <NUM>. A recapture path <NUM> is generated that requires the least (i.e., most minimal) change in course for the aircraft to recapture the planned flight path <NUM>. Recapture path <NUM> is likely the most perceptibly smooth recapture path. In various embodiments, the system <NUM> stays in the managed mode until the computed recapture path is executed and the aircraft <NUM> is safely landed.

As may be appreciated, a selected recapture path strategy and generated recapture path may vary based on whether the trajectory of the aircraft at the current heading intersects with the planned flight path or not, this is illustrated in <FIG> and <FIG>. In <FIG>, the aircraft's (<NUM>) current heading <NUM> intersects with the planned flight path <NUM>. Planned flight path <NUM> includes geospatial midpoints <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, connected in series. Leg <NUM> extends from geospatial point <NUM> to <NUM> and indicates a planned flight path leg at the time the interrupt <NUM> is received. When the interrupt <NUM> is received, the aircraft <NUM> is distance <NUM> from the leg <NUM>, and the control module <NUM> generates a shortest recapture path for immediate response to the interrupt <NUM>: recapture path <NUM>, which would place the aircraft <NUM> back on the planned flight path at point <NUM>, which is along leg <NUM>, slightly before geospatial point <NUM>. Advantageously, the control module <NUM> is not limited to only generating recapture paths associated with waypoints. To further illustrate this advantage, in another scenario, the control module <NUM> generates a temporally later recapture path <NUM>, which places the aircraft <NUM> back on the planned flight path at point <NUM>, which is post geospatial point <NUM>, and is also intra-leg.

In <FIG>, the aircraft's (<NUM>) current heading <NUM> does not intersect with the planned flight path <NUM>. Planned flight path <NUM> includes geospatial midpoints <NUM>, <NUM>, <NUM>, and <NUM> connected in series in the direction of travel of the aircraft <NUM>. Leg <NUM> is the planned flight path leg. Points P1, P2, PN and PF are in series on a trajectory defined by the heading <NUM> of the aircraft <NUM>, and therefore depict locations as well as points in time during the aircraft travel. The control module <NUM> may, responsive to processed inputs, generate one or more of: the recapture path <NUM> to recapture the planned flight path from point P1, the recapture path <NUM> to recapture the planned flight path from point P2, and a change to heading <NUM> at point PN. Point PF represents a final point at <NUM> along the trajectory of the heading <NUM> for which a recapture path can be generated.

The concepts introduced in <FIG> may be further illustrated with various use cases depicted in <FIG>. In <FIG>, aircraft <NUM> is at an initial point <NUM>, traveling along the planned flight path (labeled primary fpln). The aircraft <NUM> is in a "cruise" phase of flight and the aircraft <NUM> is flying in all managed modes. A received ATC instruction to fly in a manual mode at heading <NUM> degrees (HDG <NUM>') is received by the system <NUM>, and at point <NUM>, the pilot changes course of the aircraft <NUM> to HDG <NUM>'. An interrupt <NUM> is received, and the control module <NUM> categorizes the interrupt as one of: (i) obstacle, (ii) equipment/fuel, or (iii) pilot health monitor. In some embodiments, the control module <NUM> next determines that there is no need to re-route to a diversion airport before further responding to the interrupt. Responsive to the interrupt <NUM>, the control module <NUM> begins a managed mode in which it generates/computes a recapture path. The control module <NUM> selects a rejoining leg of the planned flight path at which to rejoin the planned flight path. The control module <NUM> selects, as a function of the interrupt category and rejoining leg, a recapture path strategy from among a variety of available recapture path strategies. In an embodiment, the control module <NUM> selects a recapture path strategy from among (i) lateral, (ii) vertical, and (iii) mixed lateral and vertical. The control module <NUM> generates the recapture path <NUM> and automatically guides the aircraft <NUM>, along recapture path <NUM>, back to the planned flight path at <NUM>. As may be understood from the figures, the control module <NUM> may determine anywhere (i.e., any location) along the rejoining leg to rejoin the aircraft <NUM>, and the generated recapture path may return the aircraft <NUM> to the rejoining leg at the determined location of the selected rejoining leg. In order to automatically guide the aircraft <NUM> back to the planned flight path, the control module generates flight guidance commands along the recapture path <NUM> and re-takes control as LNAV and/or NAV (lateral navigation and/or navigation) from the previous manual operation at <NUM> and <NUM>.

<FIG> depicts an approach and descent use case. At <NUM>, the aircraft <NUM> is flying in all managed modes along the planned flight path, and in an approach and/or descent phase of flight. An ATC instruction "Fly HDG <NUM>‴ is received by the system <NUM>. At <NUM>, the pilot begins manual control and changes course to adhere to the instruction to fly at heading <NUM>'. At <NUM>, an interrupt is received. The control module <NUM> categorizes the interrupt, as one of: (i) obstacle, (ii) equipment/fuel, or (iii) pilot health monitor. Responsive to the interrupt <NUM>, the control module <NUM> begins a managed mode in which it generates a recapture path. The control module <NUM> selects, at least in part as a function of the interrupt category, a recapture path strategy from among a variety of supported recapture path strategies. In an embodiment, the control module <NUM> (i.e., the programmed processor <NUM>) selects a recapture path strategy from among (i) lateral, (ii) vertical, and (iii) mixed lateral and vertical. In this use case, the control module <NUM> further selects a recapture path strategy to ensure a stable approach and to avoid undue level flight during the approach and descent. As used herein, avoiding undue level flight means minimizing a distance to a destination while maintaining stability. As described below, in descent and approach phases of flight, the control module <NUM> (i.e., the programmed processor <NUM>) considers vertical trajectory to ensure a stable approach and landing; this does not mean pure lateral recapture path strategy is impossible during a descent and approach phase of flight, but a stable approach and landing is ensured. The control module <NUM> generates the recapture path <NUM> and automatically guides the aircraft <NUM>, along recapture path <NUM>, back to the planned flight path at <NUM>. In order to automatically guide the aircraft <NUM> back to the planned approach and/or descent, the control module generates flight guidance commands along the recapture path <NUM> and re-takes control as LNAV and/or NAV from the previous manual operation at <NUM> and <NUM>.

As mentioned, generating the recapture path includes selecting from among one or more strategies. The above described lateral recapture path strategies are generated as a function of the current location and heading of the aircraft <NUM> with respect to the geospatial midpoints constituting the planned flight path. However, in certain scenarios, lateral path recapture strategy is affected by an interrupt that is an obstacle such as an object or weather hazard. In <FIG>, an exemplary lateral strategy enhanced with obstacle avoidance is depicted. The control module receives an interrupt and categorizes it as an obstacle interrupt. The control module <NUM> processes one or more of weather data and terrain data to identify the location, area, and a center of the obstacle(s). In <FIG>, the obstacles are terrain <NUM> (<NUM>) and terrain <NUM> (<NUM>). The control model <NUM> employs an obstacle avoidance strategy to block the area of the obstacle from consideration prior to generating the recapture path(s). In the exemplary embodiment, the control module <NUM> employs an octagon method, constructing octagon shapes, centered on the center of the obstacle, to block out areas associated with obstacles. The control module <NUM> constructs a first octagon shape of an area that is large enough to completely surround terrain <NUM>, and a second octagon shape of an area that is large enough to completely surround terrain <NUM>. The selected octagon areas incorporate a preprogrammed safety margin. The control module <NUM> generates one or more recapture paths after blocking the obstacles. The recapture paths may pass alongside the octagons and therefore, may take a shape that reflects one or more sides of the octagons. In <FIG>, a first recapture path <NUM> recaptures the planned flight path <NUM> at <NUM>, by altering course prior to reaching the area blocked by the obstacle(s), and a second recapture path <NUM> recaptures the planned flight path <NUM> at <NUM>, by altering course after passing by the area blocked by the obstacle(s).

An exemplary vertical strategy is shown in <FIG>. Aircraft <NUM> is located above the planned flight path <NUM> and has a landing destination <NUM>. In this example, the rejoining leg is the ILS <NUM> landing. A pre-programmed selected altitude <NUM> is employed to determine the vertical path to recapture a trajectory of the instrument landing system ILS <NUM> (i.e., an ILS extension). If the aircraft <NUM> is above the ILS extension as shown in <FIG>, the intersection with selected altitude creates three options. Option (<NUM>), when the intersection with the ILS extension is in front of the first threshold <NUM>, aircraft recapture path descends to the selected altitude <NUM> and continues horizontally to the ILS <NUM> for landing. Option (<NUM>), when the intersection with the ILS <NUM> is behind the second threshold <NUM>, the aircraft recapture path bends to intersect with an extension of the ILS. Option (<NUM>), when the intersection with the ILS <NUM> is between the first threshold <NUM> and the second threshold <NUM>, the aircraft recapture path descends to the selected altitude <NUM> and then descends at a small angle <NUM> toward the ILS <NUM>. In an embodiment, a small angle <NUM> is less than <NUM> degrees. The definition of a small angle <NUM> is aircraft (and condition) dependent; for example, in an embodiment, it is chosen to affect deceleration assuming the use of extended flaps and airbrakes. In another example, not shown, if the aircraft <NUM> is below the ILS <NUM> extension, the recapture path includes descending to the selected altitude <NUM> and from there (i) traveling horizontally to the ILS <NUM> when there is enough distance to do so, or from there (ii) descending at a small angle <NUM> to intersect with the ILS <NUM>.

In <FIG>, a mixed lateral and vertical recapture path strategy is depicted in a three-dimensional drawing showing a vertical approach profile with planned flight path <NUM> to a runway <NUM>. An altitude scale <NUM> along the left side depicts from zero to <NUM> feet above ground. The aircraft <NUM> is descending vertically and tracing out a lateral path demarked at <NUM>. The planned flight path <NUM> includes a final approach fix (FAF <NUM>). Aircraft <NUM> is not on the planned flight path <NUM> when the interrupt is received and the control module <NUM> begins the managed mode. The control module <NUM> generates a shortest recapture path <NUM> that rejoins at <NUM>. The shortest recapture path <NUM> rejoins the descent leg after the FAF <NUM>, which means it is rejoining at a steep and/or sharp angle <NUM>. As used herein, a steep and/or sharp angle is less than <NUM> degrees. Additionally, the shortest recapture path <NUM> rejoins the descent leg in an above-path situation (depicted by the vertical bar <NUM>). The control module <NUM> determines, based on the angle <NUM> and the above path distance, that although the recapture path <NUM> is shortest, it poses an unacceptable risk of an unstable approach. The control module <NUM> then generates a longer recapture path <NUM>, which rejoins at <NUM> and allows vertical recapture of the approach profile prior to the FAF <NUM> and enables a stable approach. In an embodiment, the mixed lateral and vertical strategy is used to compute a most energy efficient descent to the stabilized approach.

The control module <NUM> generates guidance controls for the aircraft <NUM> to execute the determined recapture path. In addition to the guidance that directs the aircraft along the lateral and/or vertical path, the control module <NUM> generates performance and speed targets for geospatial midpoints along the recapture path. As stated, the various waypoints or geospatial midpoints making up the planned flight path include performance and speed targets; accordingly, a leg that connects any two waypoints has associated performance and speed targets that are informed by the performance and speed targets at the connected waypoints. Therefore, the control module <NUM> assures that the aircraft <NUM> arrives at the determined rejoining leg meeting the performance and speed associated with the rejoining leg. The control module <NUM> evaluates the current aircraft performance and speed and the rejoining leg performance and speed targets to create a deceleration or acceleration profile associated with the recapture path. In managed mode, the control module <NUM> controls the performance and speed of the aircraft <NUM> as it guides the aircraft <NUM> along the recapture path.

The system <NUM> may make its determinations and selections in accordance with a method such as method <NUM> of <FIG>. With continued reference to <FIG>, a flow chart is provided for a method <NUM> for providing a system <NUM>, in accordance with various exemplary embodiments. Method <NUM> represents various embodiments of a for weather impact prediction. For illustrative purposes, the following description of method <NUM> may refer to elements mentioned above in connection with <FIG>. In practice, portions of method <NUM> may be performed by different components of the described system. It should be appreciated that method <NUM> may include any number of additional or alternative tasks, the tasks shown in <FIG> need not be performed in the illustrated order, and method <NUM> may be incorporated into a more comprehensive procedure or method having additional functionality not described in detail herein. Moreover, one or more of the tasks shown in <FIG> could be omitted from an embodiment of the method <NUM> if the intended overall functionality remains intact.

The method starts, and the control module <NUM> is initialized and the system <NUM> is in operation. Initialization may comprise uploading or updating instructions and applications <NUM>, program <NUM>, and various display and formatting instructions that may be stored in the database <NUM>. Stored variables may include, for example, configurable, preprogrammed values, thresholds, small angle definitions, parameters for setting up a user interface, the shapes used in recapture path strategies, various colors and/or visually distinguishing techniques used for depicting recapture paths, and related icons and alerts. In some embodiments, program <NUM> includes additional instructions and rules for rendering information differently based on type of display device in display system <NUM>. Initialization may also include identifying external sources and/or external signals and the communication protocols to use with each external source.

At <NUM>, a planned flight plan is received, including a planned flight path with a stabilized approach. At <NUM>, the method <NUM> detects that the aircraft is being operated in manual mode and that the current/active flight path is not the same as the planned flight path. At <NUM>, navigation data and aircraft state data are continually received. In various embodiments, at <NUM>, weather data is received and/or terrain data is accessed. At <NUM>, the method <NUM> continually displays the active/current flight path and the planned flight path. At <NUM>, if an interrupt is received, it proceeds to <NUM>. At <NUM>, if an interrupt is not received, it cycles back to any of <NUM>, <NUM> or <NUM>. As may be appreciated, the display system <NUM> continuously updates the lateral image <NUM> to indicate the aircraft <NUM> at its current position and with terrain and weather imagery based on received data. At <NUM>, a received interrupt is categorized as one of (i) obstacle, (ii) equipment/fuel, or (iii) pilot health monitor. At <NUM>, responsive to the interrupt, a managed mode begins. While in managed mode, the method identifies a rejoining leg of the FP (<NUM>) and selects a location on rejoining leg for rejoining it (<NUM>). The control module <NUM> supports rejoining the rejoining leg at any location along the rejoining leg. Steps <NUM> and <NUM> may be based in part on the category of the interrupt. At <NUM>, a recapture path strategy is determined from among (i) lateral, (ii) vertical, and (iii) mixed lateral and vertical. According to the invention the selected recapture path strategy is that of a mixed lateral and vertical. At <NUM>, the method employs the determined recapture path strategy to compute a recapture path to rejoin at the location. In some embodiments, the rejoining leg and or the location on the rejoining leg are a function of the interrupt category and the selected strategy. At <NUM>, more than one recapture path may be generated and evaluated by the control module <NUM>, prior to selecting just one recapture path to execute (see, for example, <FIG>). As mentioned above, in some embodiments, the recapture paths are generated in advance, and at <NUM> the recapture paths are simply evaluated to determine which is the most appropriate. The computed/generated recapture path includes speed targets and configuration requirements at dedicated points along the recapture path. At <NUM>, the method predicts aircraft state data along the recapture path, and at <NUM>, the control module <NUM> generates guidance controls along the recapture path. After <NUM>, the method <NUM> is shown as ending, but it is understood that this generated recapture path and associated performance and guidance parameters may then be executed automatically, meaning that the control module <NUM> retakes control of the operation of the aircraft <NUM> and executes the determined recapture path.

Thus, technologically improved flight guidance systems and methods are provided that respond to an interrupt received while in manual mode and off-path by generating a recapture path and guidance for automatic guidance of an aircraft back along the recapture path to a planned flight plan.

To clearly illustrate the interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the application and design constraints imposed on the overall system.

Skilled artisans may implement the described functionality in varying ways for each application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

Further, the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

The steps of the method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a controller or processor, or in a combination of the two.

When "or" is used herein, it is the logical or mathematical or, also called the "inclusive or. " Accordingly, A or B is true for the three cases: A is true, B is true, and, A and B are true. In some cases, the exclusive "or" is constructed with "and;" for example, "one from A and B" is true for the two cases: A is true, and B is true.

Claim 1:
A flight guidance system for an aircraft, comprising:
a source of a planned flight plan including a planned flight path with a stabilized approach;
a source of navigation data including altitude, speed, heading, roll, bank, and location;
a source of current aircraft state data including engine status, configuration, thrust status, fuel status, and flight mode; and
a control module comprising a processor and memory, the processor operationally coupled to the source of a planned flight plan, the source of navigation data, and the source of aircraft state data, the control module thereby configured to:
identify an active flight path different than the planned flight path when the aircraft is being operated in manual mode;
receive an interrupt and categorize the interrupt as an obstacle; and
responsive to the interrupt, begin a managed mode; and
while in managed mode:
identify a rejoining leg of the planned flight path at which to rejoin the planned flight path;
identify a location on the rejoining leg at which to rejoin;
select a recapture path strategy that is mixed lateral and vertical, wherein the control module is configured to employ an octagon method to compute the recapture path, wherein the octagon method comprises constructing an octagon around the obstacle, the octagon having a predetermined safety margin around the obstacle, and wherein the recapture path is along one or more sides of the octagon;
compute a recapture path to the location on the rejoining leg using the selected recapture path strategy, the computed recapture path including speed targets and configuration requirements at dedicated points along the recapture path;
predict aircraft state data along the recapture path; and
generate guidance controls for the aircraft along the recapture path.