Patent Description:
It is a common procedure at major airports for ATC (Air Traffic Control) to clear arriving aircraft for a visual or instrument approach, preceded by radar vectors (instructions issued by ATC to facilitate the smooth and expeditious flow of traffic). The approach clearance is often accompanied by a request to maintain a prescribed visual separation, referred to as a "safe separation," time from a preceding aircraft. In these scenarios, it is up to the pilot to rely on visual cues and to manually adjust a heading, a rate of descent and an airspeed of the ownship aircraft, such that the preceding aircraft is followed with the safe separation.

The demands of maintaining visual separation during a visual approach cause a significantly and objectively increased workload on a pilot during approach, since they require the pilot to continuously scan flight instruments, follow traffic outside of the ownship aircraft, prepare for an approach and, complete checklist items. Because maintaining visual separation during an approach is reliant upon visual cues, its accuracy presents a technical problem. It is further a technical problem in that it can only be performed in VMC (Visual Meteorological Conditions).

These technical problems can lead to further technical problems, such as, reduced efficiency for pilots and airports. For example, due to the workload described above, the pilot may not have time and mental capacity left to optimize a trajectory of the ownship aircraft, to reduce fuel burn, noise and emissions. Additionally, pilots may be inclined to overcompensate under stress, by maintaining a larger than prescribed separation from the preceding traffic. This, in turn, reduces the capacity of the airport.

Known available solutions have their own limits. One available technical solution is CAVS, or CDTI Assisted Visual Separation (CDTI stands for Cockpit Display of Traffic Information). However, CAVS still requires the pilot to read and interpret traffic textual information (such as distance and closure rate) and to manually adjust a heading, a descent rate and a speed target based thereon. Another available solution is an "automatic paired approach. " However, automatic paired approach systems are directed to parallel runways and the final approach segment. Additionally, there are some available formation-flying algorithms. However, they are directed to the narrow issue of maintaining a specific position with respect to a lead aircraft, they are not understood to guide aircraft on final approach.

Accordingly, improved aircraft systems and methods that provide automatic sequencing behind preceding aircraft on approach, are desirable. Furthermore, other desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. <CIT> discloses an aircraft control system in which the host aircraft receives information from another aircraft in order to generate a signal for use in the host aircraft to control separation between the host aircraft and the other aircraft while the aircraft are within a predefined range of a location where the aircraft plan to land.

<CIT> discloses a flight management system to determine a rejoin turn location based upon a heading to allow proper spacing between an aircraft and an identified target aircraft. The flight management system monitors for deviation from assigned airspace, winds, turn radius and desired airport speed profile for the approach to further refine a turn-back location.

<CIT> discloses method and apparatus of controlling the movement of an aircraft in which a turn path off of a planned route for an aircraft comprising a turn to direct the aircraft to an intercept point on the planned route is determined.

Provided is a method for an ownship aircraft to sequence behind a lead aircraft on an approach to a runway as provided in claim <NUM>.

Also provided is a system for sequencing an ownship behind a lead aircraft on an approach to a runway as provided in claim <NUM>.

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

As alluded to, maneuvering visually prior to joining a final approach is one of the least automated and most unpredictable phases of flight, which also concentrates some of the highest workload, since the visual approach requires the pilot to continuously scan flight instruments, follow traffic outside of the ownship aircraft, prepare for the approach, and complete checklist items. Further, the visual approach is reliant upon visual cues and can only be performed in VMC (Visual Meteorological Conditions). Under the stress of these visual approach scenarios, pilots may be inclined to overcompensate, by maintaining a larger than the prescribed separation time from the preceding traffic. Alternately, a pilot may inadvertently get too close behind the preceding aircraft (i.e., a smaller time than the safe separation time). When a pilot gets too close to the preceding aircraft, the pilot may encounter wake turbulence, and/or may be required to abort the approach and perform a go-around procedure at that time. Each of these potential pilot reactions to visual procedures can reduce the efficiency and capacity of the airport and the aircraft.

Available solutions have known limitations. For example, CAVS is very cognitively demanding, as seeing traffic information presented on a display, accompanied with textual information such as a distance and a closure rate, is not an intuitive human-machine interface, and may lead to the pilot misjudging the information presented. And, automatic paired approach systems are limited to controlling airspeed of the trailing aircraft, and only once it is established on a final approach segment.

The embodiments described herein provide a technical solution that improves upon the functionality of flight guidance systems for approach procedures and also provide an objectively improved human-machine interface during this cognitively demanding time. The embodiments provided join the current flight to a final approach segment to a given runway while maintaining a desired safe separation time from preceding aircraft. The embodiments provided automate a much larger portion of the approach. Specifically, and advantageously, the embodiments provided generate lateral guidance, vertical guidance, and speed targets, to thereby automate the turning and descending task with an assured safe separation.

<FIG> is a schematic block diagram of an aircraft system <NUM> with a system for automatic sequencing behind preceding aircraft on approach (shortened herein to system for automatic sequencing) <NUM>, in accordance with an exemplary embodiment. The illustrated embodiment of the aircraft system <NUM> includes, without limitation: at least one processing system <NUM>; an appropriate amount of data storage <NUM>; a displays system <NUM>; a user interface <NUM>; control surface actuation modules <NUM>; other subsystem control modules <NUM>; a flight management system (FMS) <NUM>, a navigation system <NUM>, a system for automatic sequencing <NUM> and a communication module <NUM>. These elements of the aircraft system <NUM> may be coupled together by a suitable interconnection architecture <NUM> that accommodates data communication, the transmission of control or command signals, and/or the delivery of operating power within the aircraft system <NUM>. It should be understood that <FIG> is a simplified representation of the aircraft system <NUM> that will be used for purposes of explanation and ease of description, and that <FIG> is not intended to limit the application or scope of the subject matter in any way. In practice, the aircraft system <NUM> and the host aircraft will include other devices and components for providing additional functions and features, as will be appreciated in the art. Furthermore, although <FIG> depicts the aircraft system <NUM> as a single unit, the individual elements and components of the aircraft system <NUM> could be implemented in a distributed manner using any number of physically distinct pieces of hardware or equipment.

The processing system <NUM> may be implemented or realized with one or more general purpose processors, content addressable memory, digital signal processors, application specific integrated circuits, field programmable gate arrays, any suitable programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform the functions described here. A processor device may be realized as a microprocessor, a controller, a microcontroller, or a state machine. Moreover, a processor device may be implemented as a combination of computing devices (e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration).

As alluded to, the lead aircraft is initially identified in a command received from air traffic control (ATC), in the course of clearing the ownship aircraft for an instrument or visual approach. As described in more detail below, the processing system <NUM> may implement an automatic sequencing algorithm, which may be embodied in a software program <NUM>, and, when operating in that context, may be considered the system for automatic sequencing <NUM>. In accordance with various embodiments, processing system <NUM> is configured to execute the automatic sequencing algorithm to perform the tasks of, at least, calculating an arrival time of the lead aircraft at the runway, determining a target point for the ownship aircraft to merge onto a centerline of the runway, and guide the ownship aircraft (i) to join the runway centerline at the target point, and (ii) to assure the ownship aircraft stays at the desired separation time after the lead aircraft.

In addition, the processing system <NUM> may generate commands, which may be communicated through interconnection architecture <NUM> to various other aircraft system <NUM> components. Such commands may cause the various system components to alter their operations, provide information to the processing system <NUM>, or perform other actions, nonlimiting examples of which will be provided below.

The data storage <NUM> may be realized as RAM memory, flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, the data storage <NUM> can be coupled to the processing system <NUM> such that the processing system <NUM> can read information from, and write information to, the data storage <NUM>. In various embodiments, the data storage <NUM> may be initialized to have stored therein the software program <NUM>, containing the programming instructions of the automatic sequencing algorithm. In the alternative, the data storage <NUM> may be integrated with the processing system <NUM>. As an example, the processing system <NUM> and the data storage <NUM> may reside in an ASIC.

In practice, any functional or logical module/component of the aircraft system <NUM> might be realized as an algorithm embodied in program code that is maintained in the data storage <NUM>. For example, the processing system <NUM>, the displays system <NUM>, the control modules <NUM>, <NUM>, and/or the communication module <NUM> may have associated software program components that are stored in the data storage <NUM>. Accordingly, as used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including without limitation: application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. In various embodiments, modules of aircraft system <NUM> are stored in data storage <NUM> and executed by processing system <NUM>.

The displays system <NUM> includes one or more lateral displays, vertical displays, and multi-function displays and associated graphics processors. Processing system <NUM> and displays system <NUM> cooperate to display, render, or otherwise convey one or more graphical representations, synthetic displays, graphical icons, visual symbology, or images associated with operation of the host aircraft. An embodiment of the aircraft system <NUM> may utilize existing graphics processing techniques and technologies in conjunction with the displays system <NUM>. For example, displays system <NUM> may be suitably configured to support well known graphics technologies such as, without limitation, VGA, SVGA, UVGA, or the like.

User interface <NUM> is suitably configured to receive input from a user (e.g., a pilot) and, in response to the user input, to supply appropriate command signals to the processing system <NUM>. The user interface <NUM> may include any one, or any combination, of various known user interface devices or technologies, including, but not limited to: a cursor control device such as a mouse, a trackball, or joystick; a keyboard; buttons; switches; knobs; levers; or dials. Moreover, the user interface <NUM> may cooperate with the displays system <NUM> to provide a graphical user interface. Thus, a user can manipulate the user interface <NUM> by moving a cursor symbol rendered on a display, moving a finger along a touch screen surface, and the user may use a keyboard to, among other things, input textual data. For example, after receiving ATC commands to follow a lead aircraft, the pilot could view a display of a plurality of traffic on a displays system <NUM> and manipulate the user interface <NUM> to select the lead aircraft from among the plurality of traffic displayed, for use by the processing system <NUM>, and the like.

In an exemplary embodiment, the communication module <NUM> is suitably configured to support data communication between the host aircraft and one or more external sources <NUM>. For example, the communication module <NUM> may be designed and configured to enable the host aircraft to communicate with a plurality of regional air traffic control (ATC) authorities, weather data sources that provide wind velocity and wind direction at runways, as well as satellite weather reports (wind velocity and wind direction at various geographic areas along the flight plan), automatic terminal information service (ATIS), other ground and air communications, etc. In this regard, the communication module <NUM> may include or support a datalink subsystem that can be used to communicate with external sources <NUM>, such as air traffic control (ATC) and satellite weather data providers (WX), preferably in compliance with known standards and specifications.

In certain implementations, the communication module <NUM> is also used to communicate with other aircraft (often referred to as traffic) that are near the host aircraft and optionally also with ground vehicles. As such, the communication module <NUM> may be configured for compatibility with a Traffic Information System Broadcast (TIS-B), Automatic Dependent Surveillance-Broadcast (ADS-B) technology, with Traffic and Collision Avoidance System (TCAS) technology, and/or with similar technologies. Received traffic data for each traffic aircraft may include an altitude, position information (location and orientation), a flight identification, velocity information, turbulence category information, and the like.

Flight management system <NUM> (FMS) (or, alternatively, a flight management computer) is located onboard an aircraft and is included in aircraft system <NUM>. Flight management system <NUM> is coupled to displays system <NUM> and may include one or more additional modules or components as necessary to support navigation, flight planning, and other aircraft control functions in a conventional manner. In addition, the flight management system <NUM> may include or otherwise access a terrain database, airport and navigational databases (including airport diagrams, with locations, elevations, geometries, and orientations of runways and runway centerlines, STAR, SID, and en route procedures, for example), geopolitical database, taxi database, or other information for rendering a navigational map or other content on displays system <NUM>, as described below. The FMS <NUM> is capable of tracking a flight plan and also allowing a pilot and/or autopilot system (not shown) to make changes to the flight plan, as described below. In various embodiments, the processing system <NUM> provides the FMS <NUM> with the target point (described below).

The navigation system <NUM> is configured to obtain one or more navigational parameters associated with operation of an aircraft. The navigation system <NUM> may include a global positioning system (GPS), inertial reference system (IRS) and/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 navigation system, as will be appreciated in the art. In an exemplary embodiment, the navigation system <NUM> is capable of obtaining and/or determining navigation data, including but not limited to: the altitude, the current location of the aircraft (e.g., with reference to a standardized geographical coordinate system); the heading of the aircraft (i.e., the direction the aircraft is traveling in relative to some reference); the ground speed or velocity; and, the orientation (roll, pitch, yaw) of the aircraft. A combination of the location and orientation may be referred to as a position of the ownship aircraft. The navigation system <NUM> provides the navigation data to the interconnection architecture <NUM>, from which other aircraft system <NUM> components, such as the processing system <NUM>, may receive and process the navigation data.

Control surface actuation modules <NUM> include electrical and mechanical systems configured to control the orientation of various flight control surfaces (e.g., ailerons, wing flaps, rudder, and so on). Processing system <NUM> and control surface actuation modules <NUM> cooperate to adjust the orientation of the flight control surfaces in order to affect the attitude and flight characteristics of the host aircraft.

Processing system <NUM> also may communicate with other subsystem control modules <NUM> to affect various aspects of aircraft operations. For example, but not by way of limitation, the other subsystem control modules <NUM> may include, a throttle/thrust control module, a flight director heading select module, a flight director vertical speed module, a propulsion system, and a radar module that signals to the processing system <NUM> when the ownship aircraft is flying in a visual or radar mode. In various embodiments, the subsystem control modules <NUM> further include, a landing gear actuation module, a cabin environment control system and a data entry system.

<FIG> is a process diagram showing an exemplary partition of automatic sequencing processes <NUM>. In an embodiment, the automatic sequencing processes <NUM> may be implemented as software program modules, for example, collectively, as a program product that can be uploaded into an aircraft system <NUM> and executed by a processing system <NUM>. In various embodiments, automatic sequencing processes <NUM> are implemented as an application specific integrated circuit. In still other embodiments, automatic sequencing processes <NUM> are implemented as a combination of hardware and software. In an embodiment, a target point determination process <NUM> receives some onboard data and some data from external sources <NUM>. The target point determination process <NUM> receives a runway position, inbound course for the ownship aircraft, approach slope, final approach fix position, and wind data (this information may be received from on-board aircraft systems such as the FMS <NUM> and/or the navigation system <NUM>). An external source <NUM>, such as a traffic information service-broadcast (TIS-B) provides the target point determination process <NUM> with lead aircraft position, track, and ground speed (or velocity). The target point determination process <NUM> determines track miles remaining, and a target position turn direction. In various embodiments, the target point determination process <NUM> makes these determinations by processing received inputs with an aircraft-specific track miles required for deceleration for the ownship (in an embodiment, this value may be stored in the data storage <NUM>).

As mentioned above, the automatic sequencing algorithm advantageously automates the turning and descending components of flying the visual approach while assuring the safe separation. In the exemplary embodiment shown in <FIG>, to meet this objective, the automatic sequencing processes <NUM> may be partitioned as a speed target computation process <NUM>, a vertical target computation process <NUM> directed to descents, and a lateral computation process <NUM> directed to turning, each of which receive and process inputs from the target point determination process <NUM>, and each generating signals that command and control other subsystem control modules <NUM>, and/or control surface actuation modules <NUM> to effect the automated turning and descending of the ownship aircraft flight. Additionally, the target point <NUM> that is determined by the automatic sequencing processes <NUM> is an output that can be provided to the FMS <NUM> for navigation.

In <FIG>, with reference to <FIG>, the aircraft system <NUM> described above may be implemented by a processor-executable method <NUM> for automatic sequencing. 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> as long as the intended overall functionality remains intact.

The method starts, and at <NUM> navigation data for the ownship aircraft is received. In an embodiment, the navigation data includes an altitude, a position, and a velocity for the ownship aircraft. A position, elevation, and orientation for a runway is received or referenced at <NUM>. In various embodiments, <NUM> is omitted. In other embodiments, at <NUM>, the processing system <NUM> confirms that the ownship is operating an instrument approach preceded by radar vectors), this may be done by the processing system <NUM> receiving and processing radar vectors in the other subsystems and control modules <NUM>. A turbulence category for the lead aircraft, as well as an altitude, position, and velocity of the lead aircraft is received or identified from among a plurality of received traffic data at <NUM>. In various embodiments, a lead aircraft heading and track is expected to be the runway heading. In various embodiments, a TIS-B system provides the traffic data. In various embodiments, a wind speed and wind direction may be received from a weather data source at <NUM>. Although illustrated sequentially, the method steps <NUM>-<NUM> can be occurring concurrently and updating as appropriate. At <NUM>, a pilot selection of the lead aircraft triggers the aircraft system <NUM> to begin the automatic sequencing algorithm based on the available data and information from method steps <NUM>-<NUM>. In various embodiments, the processing system <NUM> prompts the pilot to select a lead aircraft via an alphanumeric message on the displays system <NUM>, and the pilot selection is responsive to the prompt. In various embodiments, the processing system <NUM> compares the pilot selected lead aircraft to a lead aircraft identified in a command from ATC to confirm that the correct lead aircraft has been selected by the pilot before moving to the next steps.

The automatic sequencing algorithm may include the following steps. An arrival time of the lead aircraft at the runway is calculated at <NUM>. A target point for the ownship to merge onto a centerline of the runway is determined at <NUM> to be a desired separation time later than the lead aircraft passes through the same point. At <NUM>, the sequencing method automatically, and without further human input, computes and provides vertical commands, lateral commands, and a speed target to: (i) guide the ownship to the final approach segment via the target point (ii) with a desired separation from preceding lead aircraft and at an optimum descent profile for the ownship aircraft in terms of fuel burn and time of flight. The provided flight guidance can be flight director vertical and lateral commands, as well as a speed target; autopilot is not required. In various scenarios, a pilot may follow the flight director guidance and speed target manually. In an embodiment, the provided flight guidance can be followed by pilot, manually. In an embodiment, when Autopilot and Autothrottle functions are engaged, the provided flight guidance can be fully automated.

In various embodiments, as shown in <FIG>, at <NUM> includes turning the heading of the ownship aircraft, as described with respect to the lateral target computation processes <NUM> and the target position turn direction. The vertical commands, lateral commands, and speed target guidance from above may include commanding and controlling various subsystem control modules <NUM> and control surface actuation modules <NUM> to automate the turning and descending that is required to get the ownship aircraft to the target point as described herein. In various embodiments, the desired separation time is provided by ATC in a command that identifies the lead aircraft. In various embodiments, the desired separation time is retrieved from a stored lookup table that takes into account aircraft specific parameters for the ownship aircraft and the lead aircraft. The automatic sequencing algorithm is illustrated in more detail in connection with <FIG>.

Turning now to <FIG>, and with reference to <FIG>, a use case illustration is provided. Runway <NUM> with runway centerline <NUM> is shown. Ownship aircraft is on a current flight at current position <NUM>. The lead aircraft is identified at an initial position <NUM> (recall position herein refers to location and orientation) on an approach to at the runway <NUM>. The aircraft system <NUM> processes available received data, such as the velocity (ground speed) of the lead aircraft and the initial position <NUM> of the lead aircraft, to calculate an arrival time of the lead aircraft at the runway <NUM>. The aircraft system <NUM> determines a distance to a target point <NUM> on the runway centerline <NUM> by referencing the arrival time of the lead aircraft, a desired safe separation <NUM>, the current position <NUM> of the ownship aircraft and the velocity (ground speed) of the ownship aircraft. The aircraft system <NUM> may anticipate, based on available data that the lead aircraft will be at position <NUM> when the ownship aircraft arrives at the target point <NUM>, which accommodates the desired safe separation <NUM>. Once the aircraft system <NUM> has determined these values, the aircraft system <NUM> implements the processes described in connection with <FIG> to guide the ownship aircraft from the current position <NUM> to the target point <NUM>, and from the target point <NUM> to a safe landing on the runway <NUM>. As shown and described with respect to the illustration in <FIG>, this automated guidance may include a turn and a descent. Flight guidance from the current position <NUM> to the target point <NUM> may include turning and descent guidance. Flight guidance from the target point <NUM> to a safe landing on the runway <NUM> does not include turning, but includes speed control guidance for descent. Thus, the aircraft system <NUM> provides a functional improvement over available flight guidance systems, as well as objectively improving the human-machine interface during an instrument approach.

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

Claim 1:
A method for an ownship aircraft to sequence behind a lead aircraft on an approach to a runway, comprising:
receiving, by a processing system onboard the ownship aircraft, an altitude, a position, and a velocity for the ownship aircraft;
receiving, by the processing system, a position, an elevation and an orientation of the runway,inbound course data for the ownship aircraft, approach slope, final approach fix position, weather data and wind data;
receiving, by the processing system via a traffic system, a turbulence category, an altitude, a position, and a velocity for the lead aircraft;
receiving, from a user interface, a pilot selection of the lead aircraft; and
by the processing system, responsive to the pilot selection of the lead aircraft:
calculating, an arrival time of the lead aircraft at the runway;
determining a target point for the ownship aircraft to merge onto a centerline of the runway by processing the arrival time of the lead aircraft at the runway with a desired separation time together with the position, the elevation and the orientation of the runway,the inbound course data for the ownship aircraft, the approach slope, the final approach fix position, the weather data and the wind data; and
computing and providing vertical commands, lateral commands, and a speed target to guide the ownship aircraft to the target point with the desired separation from the lead aircraft and at a profile selected in terms of fuel burn and speed conditions.