SYSTEM AND METHOD TO BUILD A FLYABLE HOLDING PATTERN ENTRY TRAJECTORY WHEN THE AVAILABLE SPACE IS LIMITED

A technique for building a modified entry trajectory profile for an aircraft to join a holding pattern at an entry waypoint despite the airspace available to build the entry trajectory being limited. In one aspect, instructions are received for an aircraft to join a holding pattern at an entry waypoint according to an entry trajectory profile. An airspace around the holding pattern is divided into sectors using the entry waypoint as a reference point. A discontinuity in the entry trajectory profile can be identified. In response to identifying the discontinuity in the entry trajectory profile, a modified entry trajectory profile can be built by i) determining the sector from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint; and ii) generating the modified entry trajectory profile.

FIELD

Aspects of the present disclosure relate to building an entry trajectory profile for an aircraft to enter a holding pattern.

BACKGROUND

An aircraft can include a Flight Management System (FMS) that generates a trajectory profile for the aircraft based on a flight plan. The trajectory profile can include a lateral trajectory of holding patterns. The flight crew can select a lateral navigation mode on a Flight Control System (FCS) of the aircraft to fly the aircraft along the lateral trajectory computed by the FMS. In order to join the flight plan to a holding pattern, an entry trajectory profile is built. In some instances, the space available to build the entry trajectory profile is insufficient, which leads to the FMS building a discontinuous and unflyable trajectory to enter the holding pattern. This can force the flight crew to intervene. For instance, the flight crew may be forced to either modify the flight plan or discontinue the use of the lateral guidance provided by the FMS. This can cause confusion and an increase in the workload for the flight crew, which can be especially problematic when operating in terminal areas with dense traffic or in proximity to terrain surrounding the aircraft. Accordingly, there is a need for a technique for building a continuous and flyable entry trajectory profile to safely and efficiently transition an aircraft into a holding pattern, particularly when the airspace to build the entry trajectory profile is limited.

SUMMARY

The present disclosure provides a method in one aspect, the method includes: building a modified entry trajectory profile for an aircraft to join a holding pattern at an entry waypoint, an airspace around the holding pattern is divided into a plurality of sectors using the entry waypoint as a reference point. An inbound course of the holding pattern can be used as a reference direction. The modified entry trajectory profile is built by: determining a sector from the plurality of sectors from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint; and generating the modified entry trajectory profile based at least in part on the sector determined.

In one aspect, in combination with any example aspect provided above or below, the method includes receiving instructions for the aircraft to join the holding pattern at the entry waypoint according to an entry trajectory profile; and identifying a discontinuity in the entry trajectory profile, and wherein the modified entry trajectory profile is built in response to identifying the discontinuity in the entry trajectory profile, the modified entry trajectory profile is built so that at least one aspect of the entry trajectory profile is changed.

In one aspect, in combination with any example aspect provided above or below, the modified entry trajectory profile is generated so as to intersect the entry waypoint a single time with a last segment of the modified entry trajectory.

In one aspect, in combination with any example aspect provided above or below, the sector is determined independent of a sector of the plurality of sectors in which the aircraft is physically located.

In one aspect, in combination with any example aspect provided above or below, determining the sector from the plurality of sectors includes: translating the current track angle to the entry waypoint so as to render a translated track angle, the translated track angle intersects the entry waypoint and the aircraft points at the entry waypoint; and determining a course change angle based at least in part on the translated track angle and an inbound course of the holding pattern or an inbound reference line thereof, and wherein the sector is determined based at least in part on the course change angle.

In one aspect, in combination with any example aspect provided above or below, the sector is determined by correlating the course change angle to one of a plurality of predefined angle ranges, each predefined angle range of the plurality of predefined angles ranges corresponds to one of the plurality of sectors.

In one aspect, in combination with any example aspect provided above or below, when the sector is determined as a first sector of the plurality of sectors, the modified entry trajectory profile is generated so that: i) a capture of the holding pattern is made at an inbound course of the holding pattern in a direction opposite to an inbound direction; and ii) a tear drop pattern is created that ends at the entry waypoint.

In one aspect, in combination with any example aspect provided above or below, the sector is determined as a first sector of the plurality of sectors, and wherein the method further includes: determining whether a capture of the holding pattern would be past a starting point of an inbound course of the holding pattern or a length of the inbound course of the holding pattern is shorter than two times a turn radius of turns of the holding pattern, and wherein when the capture of the holding pattern would be past the starting point of the inbound course of the holding pattern or the length of the inbound course of the holding pattern is shorter than two times the turn radius of the turns of the holding pattern, the modified entry trajectory profile is generated so that: i) a capture is made past the starting point of the inbound course at an inbound reference line, which extends from and is coaxial with the inbound course, and in a direction opposite to an inbound direction; and ii) a tear drop pattern is created having a tear drop arc built beyond a turn-to-inbound course of the holding pattern, and the tear drop ends at the entry waypoint.

In one aspect, in combination with any example aspect provided above or below, when the sector is determined as a second, third, or fourth sector of the plurality of sectors, the modified entry trajectory profile is generated so that: i) a capture of the holding pattern is made at an outbound course of the holding pattern in a direction with an outbound direction; and ii) a following pattern is created that follows the holding pattern and ends at the entry waypoint.

In one aspect, in combination with any example aspect provided above or below, the modified entry trajectory profile is generated so that, prior to the capture of the holding pattern at the outbound course, a segment of the modified entry trajectory profile crosses the outbound course.

In one aspect, in combination with any example aspect provided above or below, the sector is determined as a second, third, or fourth sector of the plurality of sectors, and wherein the method further includes: determining whether a capture of the holding pattern would be past an ending point of an outbound course of the holding pattern, and wherein when the capture of the holding pattern would be past the ending point of the outbound course of the holding pattern, the modified entry trajectory profile is generated so that: i) a capture is made past the ending point of the outbound course at an outbound reference line, which extends from and is coaxial with the outbound course, and in a direction with an outbound direction; and ii) an extended following pattern is built having an arc segment and an inbound segment, the arc segment is built beyond a turn-to-inbound course of the holding pattern, and the inbound segment ends at the entry waypoint.

In one aspect, in combination with any example aspect provided above or below, the method includes causing the aircraft to join the holding pattern at the entry waypoint by flying according to the modified entry trajectory profile.

In one aspect, in combination with any example aspect provided above or below, wherein building the modified entry trajectory profile further includes: determining a build construction based at least in part on the sector determined, the build construction being determined from one of a plurality of possible build constructions, and wherein the modified entry trajectory profile is built in accordance with the build construction.

In one aspect, in combination with any example aspect provided above or below, the method further includes determining an implementation scheme for the build construction, the implementation scheme being determined from one of a plurality of possible implementation schemes that includes at least a normal capture implementation and an extended capture implementation.

In a further aspect, a non-transitory, computer readable medium including instructions that, when executed by one or more processors, cause the one or more processors to perform an operation, the operation including: building a modified entry trajectory profile for an aircraft to join a holding pattern at an entry waypoint, an airspace around the holding pattern is divided into a plurality of sectors using the entry waypoint as a reference point, the modified entry trajectory profile is built by: determining a sector from the plurality of sectors from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint; and generating the modified entry trajectory profile based at least in part on the sector determined.

In one aspect, in combination with any example aspect provided above or below, the operation further includes: receiving instructions for the aircraft to join the holding pattern at the entry waypoint according to an entry trajectory profile; and identifying a discontinuity in the entry trajectory profile, and wherein the modified entry trajectory profile is built in response to identifying the discontinuity in the entry trajectory profile, the modified entry trajectory profile is built so that at least one aspect of the entry trajectory profile is changed.

In one aspect, in combination with any example aspect provided above or below, determining the sector from the plurality of sectors includes: translating the current track angle to the entry waypoint so as to render a translated track angle, the translated track angle intersects the entry waypoint and the aircraft points at the entry waypoint; and determining a course change angle based at least in part on the translated track angle and an inbound course of the holding pattern, and wherein the sector is determined based at least in part on the course change angle.

In one aspect, in combination with any example aspect provided above or below, the plurality of sectors include a first sector, a second sector, a third sector, and a fourth sector, and wherein when the sector is determined as a first sector of the plurality of sectors, the modified entry trajectory profile is generated so that: i) a capture of the holding pattern is made at an inbound course of the holding pattern in a direction opposite to an inbound direction; and ii) a tear drop pattern is created that ends at the entry waypoint.

In one aspect, in combination with any example aspect provided above or below, wherein the plurality of sectors include a first sector, a second sector, a third sector, and a fourth sector, and wherein when the sector is determined as a second, third, or fourth sector of the plurality of sectors, the modified entry trajectory profile is generated so that: i) a capture of the holding pattern is made at an outbound course of the holding pattern in a direction with an outbound direction; and ii) a following pattern is created that follows the holding pattern and ends at the entry waypoint.

In yet a further aspect, an aircraft is provided. The aircraft includes a system having one or more processors and one or more memory devices that store a program executable by the one or more processors to perform an operation, the operation including: building a modified entry trajectory profile by: determining a sector from a plurality of sectors from which the aircraft would approach an entry waypoint of a holding pattern with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint; and generating the modified entry trajectory profile based at least in part on the sector determined.

DETAILED DESCRIPTION

The present disclosure provides techniques for building a continuous and flyable entry trajectory profile to safely and efficiently transition an aircraft into a holding pattern, particularly when the airspace to build the entry trajectory profile is limited. For example, when an entry trajectory profile includes a discontinuity that makes it discontinuous and unflyable, the present disclosure provides a technique for building a modified entry trajectory profile to “bypass” the entry trajectory profile with the discontinuity. Unlike the entry trajectory profile, the modified entry trajectory profile provides a continuous and flyable entry trajectory to guide an aircraft into a holding pattern at an entry waypoint into the holding pattern. An airspace around the holding pattern can be divided into a plurality of sectors using an inbound reference line and the entry waypoint as a reference point. The inbound reference line extends along and/or from an inbound course of the holding pattern to provide a reference direction.

To summarize, in one example aspect, the modified entry trajectory profile can be built by determining a sector from which the aircraft would approach the entry waypoint if a current track angle of the aircraft was moved to intersect the entry waypoint and the aircraft (e.g., a nose thereof) was pointing at the entry waypoint. The sector is determined independent of the sector in which the aircraft is physically located. Based on the determined sector, a build construction can be determined. The build construction can be implemented according to an implementation scheme (e.g., a normal capture implementation or an extended capture implementation). The modified entry trajectory profile can be generated so that at least one aspect of the entry trajectory profile is changed. The modified entry trajectory profile can be built according to implementation scheme for the build construction, which is determined based on the determined sector. The aircraft can then transition to and enter the holding pattern using the modified entry trajectory profile.

The modified entry trajectory profile can provide a smooth, continuous, and flyable entry transition into a holding pattern. Generation or use of the modified entry trajectory profile can provide a number of advantages, benefits, and/or technical effects. For instance, advantageously, the modified entry trajectory profile can provide a flyable lateral trajectory that a flight control system can command the aircraft to follow without making the aircraft fly off-path. In addition, minimum flight crew intervention, if any, is needed to transition the aircraft into a holding pattern despite limited airspace, which avoids increasing the workload of the flight crew. Moreover, the modified entry trajectory profile follows the standard holding pattern entry rules as much as possible, and an annunciation to the flight crew can be provided indicating that part of the standard holding pattern entry trajectory is modified or bypassed due to the limited space available. Further, increased safety levels can be provided by improving the situational awareness of the flight crew and helping meet the airspace restrictions around the holding pattern.

FIG.1is schematic top view of an aircraft100according to example aspects of the present disclosure. The aircraft100includes a pair of wings110,112and a fuselage114. The wings110,112extend laterally outward from the fuselage114. An interior of the fuselage114can include a cockpit116and a cabin118. The aircraft100also includes a tail section120having a horizontal stabilizer122and a vertical stabilizer124. The wings110,112, the horizontal stabilizer122, and the vertical stabilizer124can all include control surfaces126(e.g., ailerons, elevators, rudder, etc.) that can be controlled to maneuver the aircraft100during flight, such as according to a flight plan. The aircraft100further includes propulsion units128,130mounted to respective wings110,112. InFIG.1, the propulsion units128,130are gas turbine engines configured as turbofans. However, in other example aspects, the propulsion units128,130can be other types of propulsion units, such as electrically-driven fans.

The aircraft100can also include a system200. In accordance with inventive aspects of the present disclosure, the system200is operable to dynamically modify an entry trajectory profile of the aircraft100during flight in response to identifying a discontinuity in the entry trajectory profile. Particularly, an entry trajectory profile can be built to provide a plan for joining a holding pattern at an entry waypoint. The entry trajectory profile can be built according to one or more standard entry trajectory profiles, for example. However, when a discontinuity in the entry trajectory profile is identified, e.g., due to insufficient available airspace, the system200can bypass the standard entry trajectory profile in favor of a modified entry trajectory profile. In this regard, the system200can dynamically generate a continuous and flyable entry transition to a holding pattern despite limited airspace. The system200is described in greater detail with respect toFIG.2.

The aircraft100ofFIG.1is provided for example purposes and is not intended to be limiting. The inventive aspects can apply to any type of aircraft or airship capable of flying in air traffic controlled airspace where holding patterns are used. In this regard, the inventive aspects of the present disclosure can apply to aircraft with any configuration of wings, tail, aerodynamic control surfaces, power plant, etc.

FIG.2is a diagram of the system200ofFIG.1. The system200can be a Flight Management System (FMS), for example. The system200includes one or more processors212and one or more memory devices214(e.g., one or more non-transitory memory devices), which can be embodied in one or more computing devices210, such as a Flight Management Computer (FMC). The one or more memory devices214can include instructions216, such as computer-readable instructions, that, when executed by the one or more processors212, can cause the one or more processors212to perform one or more operations, such as generating entry trajectory profiles for transitioning an aircraft into a holding pattern, and if necessary, building a modified entry trajectory profile. The one or more memory devices214can also store data218, such as operational rules222, recorded flight data, lookup tables, etc.

The operational rules222can include rules or guidelines set forth in Radio Technical Commission for Aeronautics (RTCA) Document DO-236C, Appendix E, ARINC Specification424, Federal Aviation Administration (FAA) guideline documents, Air Traffic Control instructions, rules specified by a manufacturer of the aircraft, rules specified by a government agency, user-entered rules, or a combination thereof. For instance, the operational rules222can set forth various constraints for turn radii at different aircraft speeds. As a non-limiting example, the operational rules222can indicate that a turn radius for an aircraft is to be computed such that the turn maneuver is coordinated (e.g., according to the coordinated turn equation). As another non-limiting example, the operational rules222can indicate that a turn radius for an aircraft is to be computed based on a constant minimum or maximum bank angle, and the current aircraft speed. Other examples are contemplated.

Further, the one or more computing devices210can include a communications interface220operable to transmit and/or receive communications to or from various associated systems and/or devices, such as over a communication bus. Example associated systems include, without limitation, an input interface224(e.g., a Control Display Unit (CDU)), one or more displays226(e.g., an Electronic Flight Instrument System (EFIS), Navigation Display (ND), and/or Multifunction Display (MFD)), one or more navigation systems228(e.g., Inertial Navigation System INS), Global Positioning System (GPS), altimeter, Air Data Computer (ADC), etc.), and/or one or more other systems230(e.g., an autopilot system, Flight Control System (FCS), Flight Data Recorder (FDR), etc.).

As shown inFIG.2, the instructions216can include a lateral transition builder240that builds or generates lateral trajectory profiles, including entry trajectory profiles that provide a plan for transitioning an aircraft into a holding pattern. Generally, a flight plan, e.g., entered into the system200by the flight crew, can be converted into a stick trajectory242, which is a sequence of straight and curved segments that may have course discontinuities between them. The lateral transition builder240creates lateral transitions between stick trajectory segments, including a lateral transition for an aircraft to enter into a holding pattern. Particularly, at block244, the lateral transition builder240can build an entry trajectory profile254for transitioning an aircraft into a holding pattern. The entry trajectory profile254can be built in accordance with the one or more operational rules222, such as the rules or guidelines set forth in RTCA Document DO-236C, Appendix E and/or ARINC Specification424.

In some instances, one or more discontinuities in the entry trajectory profile254can result. Generally, a discontinuity in the entry trajectory profile254makes the entry trajectory profile254discontinuous and unflyable. At block246, discontinuities in the entry trajectory profile254can be identified. Discontinuities can result when the space to build the entry trajectory is insufficient or limited. As one example, a flight plan is formed by legs in sequence. An entry to the holding pattern is located at an entry waypoint where the previous leg ends. When the previous leg's length is too short, and its course difference with respect to the inbound course of the holding pattern is large, there may not be enough space to build the entry transition. In such cases, one or more discontinuities in the entry trajectory profile254can result. As another example, when the present position of the airplane is close to the entry waypoint, and the flight crew enters a Direct-To command to the entry waypoint, there may not be enough space to build the entry transition. In such cases, one or more discontinuities in the entry trajectory profile254can result. As yet another example, when the present position of the airplane is close to the entry waypoint, and the flight crew engages the Lateral Navigation mode (LNAV) of the FCS, a lateral path capture can be built to the leg previous to the holding pattern, and in some instances, there may not be enough space to build the entry transition.

At block248, a determination is made as to whether a discontinuity was identified at block246. When no discontinuities are identified at block246, the entry trajectory profile254built at block244is used to build a final lateral trajectory profile258at block252. When one or more discontinuities are identified at block246, the entry trajectory profile254is “bypassed” and a modified entry trajectory profile256is built at block250and used to build the final lateral trajectory profile258at block252.

The modified entry trajectory profile256can provide a smooth, continuous, and flyable entry transition into a holding pattern. Generation of the modified entry trajectory profile256can provide a number of advantages and/or benefits. For instance, advantageously, the modified entry trajectory profile256can provide a flyable lateral trajectory that a FCS can command the aircraft to follow without making it fly off-path. Minimum flight crew intervention, if any, is needed to transition the aircraft into a holding pattern despite limited airspace, which avoids increasing the workload of the flight crew. Moreover, the modified entry trajectory profile256follows the standard holding pattern entry rules as much as possible, and an annunciation to the flight crew can be provided indicating that part of the standard holding pattern entry trajectory is modified or bypassed due to the limited space available. Further, increased safety levels can be provided by improving situational awareness, namely by showing the flight crew the actual entry trajectory profile256that the aircraft is going to fly, and helping meet the airspace restrictions around the holding pattern.

Building a Modified Entry Trajectory Profile

Example techniques for building the modified entry trajectory profile256are provided below.

FIG.3is a flow diagram of an example technique for generating the modified entry trajectory profile256at block250inFIG.2. After determining that there is a discontinuity in the entry trajectory profile254, e.g., at block248inFIG.2, the modified entry trajectory profile256can be built at block250.

At block250-1, as depicted inFIG.3, a sector can be determined, e.g., by the one or more processors212executing the lateral transition builder240(FIG.2). That is, a sector from a plurality of sectors can be determined by identifying the sector from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint.

First, with reference toFIG.4, an example manner in which an airspace around a holding pattern can be divided into different sectors will be provided.FIG.4depicts an example holding pattern300for an aircraft with the airspace being divided into various sectors using an entry waypoint310of the holding pattern300as a reference point. In this example, the holding pattern300has a predefined racetrack pattern that includes an inbound course312, a first turn314(or a turn-to-outbound course) at a fix end316of the holding pattern300, an outbound course318, and a second turn320(or a turn-to-inbound course) at an outbound end322of the holding pattern300. The inbound and outbound courses312,318are straight segments and the first and second turns314,320are curved segments and extend between and connect the respective ends of the inbound and outbound courses312,318as shown inFIG.4. The entry waypoint310is the start of the first turn314and the entry point of the holding pattern300. An inbound direction324can be defined along the inbound course312and an outbound direction326can be defined along the outbound course318of the holding pattern300. Using right-hand turns, an aircraft can fly the holding pattern300, e.g., in waiting for landing due to traffic congestion, poor weather, runway unavailability, emergencies on the ground, etc. The holding pattern300can be defined with right-hand or left-hand turns. In case of a left-hand turn holding pattern, the construction is symmetric with respect to the axis defined by an inbound reference line328.

The airspace around the holding pattern300is divided into a plurality of sectors using the entry waypoint310as a reference point. The sectors can include a first sector S1, a second sector S2, a third sector S3, and fourth sector S4. Generally, the first sector S1is defined from five degrees to one hundred ten degrees (5° to 110°) with respect to the inbound reference line328, which extends from and is coaxial with the inbound course312as shown inFIG.4, the second sector S2is defined from two hundred ninety degrees to five degrees (290° to 5°) with respect to the inbound reference line328, the third sector S3is defined from one hundred eighty degrees to two hundred ninety degrees (180° to 290°) with respect to the inbound reference line328, and the fourth sector S4is defined from one hundred ten degrees to one hundred eighty degrees (110° to 180°) with respect to the inbound reference line328. The construction of such sectors is specified in the RTCA Document DO-236C, Appendix E.

Accordingly, at block250-1, the sector is determined as one of the four sectors, or as the first sector S1, the second sector S2, the third sector S3, or the fourth sector S4. Determining the sector facilitates classification of the build construction to be implemented in building the modified entry trajectory profile256.

Second, with the first, second, third, and fourth sectors S1, S2, S3, and S4defined, the technique for determining the sector from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint will now be provided.

FIG.5depicts an example diagram showing a technique for translating a current track angle of an aircraft to a translated track angle. As shown inFIG.5, the aircraft100(represented as a triangle) has a current track angle101, or direction of motion in a horizontal plane. To determine the sector, the current track angle101is moved or translated to the entry waypoint310so as to render a translated track angle101-T. The translated track angle101-T intersects the entry waypoint310and the aircraft, or translated aircraft100-T, points at the entry waypoint310, e.g., as shown inFIG.5. Accordingly, for the example ofFIG.5, the second sector S2is the sector from which the aircraft100would approach the entry waypoint310if the current track angle101of the aircraft100is moved to intersect the entry waypoint310(i.e., moved to render the translated track angle101-T) and with the aircraft (or translated aircraft100-T) pointing at the entry waypoint310. Notably, the second sector S2is the determined sector in this example despite the aircraft100being currently physically located in the first sector S1. In this regard, the determination of the sector is determined independent of the sector in which the aircraft is physically located.

In some aspects, determining the sector from which the aircraft100would approach the entry waypoint310with the current track angle101of the aircraft100moved to intersect the entry waypoint310and with the aircraft, which has been moved as well, pointing at the entry waypoint310can be done using a course change angle. For instance, after translating the current track angle101to the entry waypoint310so as to render the translated track angle101-T, which intersects the entry waypoint310and the aircraft points at the entry waypoint310, a course change angle CCA can be determined based at least in part on the translated track angle101-T and the inbound course312of the holding pattern300. As shown inFIG.5, for example, the course change angle CCA can be determined as an angle between the translated track angle101-T and the inbound reference line328, which extends from and is coaxial with the inbound course312as previously noted. In this example, the course change angle CCA is three hundred thirty-five degrees (335°). The sector can be determined based at least in part on the course change angle CCA.

For instance, the sector can be determined by correlating the course change angle CCA to one of a plurality of predefined angle ranges. Each predefined angle range can correspond to one of the plurality of sectors. For instance, the determined course change angle CCA can be determined and correlated to one of the predefined angle ranges set forth in a lookup table, such as Table 1 presented below. By way of example, the course change angle CCA determined in the example ofFIG.5is three hundred thirty-five degrees (335°). Three hundred thirty-five degrees (335°) falls within the predefined angle range corresponding to the second sector S2. Thus, the second sector S2can be determined as the sector from which the aircraft100would approach the entry waypoint310with the current track angle101of the aircraft100moved to intersect the entry waypoint310and with the aircraft (or translated aircraft100-T) pointing at the entry waypoint310.

In yet other aspects, determining the sector can be done using other techniques, such as by translating or moving the current track angle101of the aircraft100to intersect the entry waypoint310(i.e., moved to render the translated track angle101-T) and with the aircraft (or translated aircraft100-T) pointing at the entry waypoint310, and then using recognition techniques to determine where the aircraft would be in such a translated position. For instance, inFIG.5, recognition techniques can determine that the translated aircraft100-T is positioned in the second sector S2.

At block250-2, returning toFIG.3, a build construction for generating the modified entry trajectory profile256can be determined based at least in part on the sector determined at block250-1, e.g., by the one or more processors212executing the lateral transition builder240(FIG.2). In some example aspects, at least two different types of build constructions are possible, including a first build construction (e.g., an inbound capture construction) and a second build construction (e.g., an outbound capture construction). In other example aspects, more than two build construction types are possible. One or more of the build construction types can be implemented according to at least two different implementation schemes. In some example aspects, for example, a first build construction can be implemented as a normal capture implementation or as an extended capture implementation and a second build construction can be implemented as a normal capture implementation or as an extended capture implementation. In this regard, the build construction types can have certain classes of implementation.

In some example aspects, at block250-2and with reference toFIGS.3and4, when the sector is determined as the first sector S1, the build construction is determined as a first build construction (e.g., an inbound capture construction). When the sector is determined as the second sector S2, the third sector S3, or the fourth sector S4, the build construction is determined as a second build construction (e.g., an outbound capture construction). In this regard, the build construction used to generate the modified entry trajectory profile256can be determined based on the sector determined at block250-1.

At block250-3, the modified entry trajectory profile256can be generated based at least in part on the build construction determined at block250-2, e.g., by the one or more processors212executing the lateral transition builder240(FIG.2). The modified entry trajectory profile256generated at block250-3can then be used, e.g., to build the final lateral trajectory profile258as shown inFIG.2. Example implementations of generating the modified entry trajectory profile256are provided below.

With general reference now toFIGS.3,6and7, an example manner will now be provided in which a modified entry trajectory profile can be built according to a first build construction in response to the first sector being determined as the sector.FIG.6is a diagram showing an entry trajectory profile254for transitioning an aircraft into the holding pattern300, with the entry trajectory profile254including at least one discontinuity.FIG.7is a diagram showing a modified entry trajectory profile256built according to a first build construction, with the first build construction being utilized in response to the first sector S1being determined as the sector at block250-1.

As shown inFIG.6, the entry trajectory profile254(e.g., built at block244inFIG.2) provides a discontinuous and unflyable trajectory to enter the holding pattern300, and thus, the entry trajectory profile254is identified as having a discontinuity. Particularly, the entry trajectory profile254is built so that the aircraft100is directed to the entry waypoint310, and upon reaching the entry waypoint310by way of a first segment SG1and a second segment SG2, the entry trajectory profile254provides for the aircraft100to make nearly a one hundred eighty degree (180°) turn from the entry waypoint310and fly along a third segment SG3. Such a turn would result in an impermissible flight maneuver, e.g., for violating at least one operational rule set forth in the operational rules222(FIG.2). After completing the third segment SG3, the entry trajectory profile254provides for the aircraft100to fly along a fourth segment SG4. To transition from the third segment SG3to the fourth segment SG4, another nearly one hundred eighty degree (180°) turn is planned. Such a turn would result in another impermissible flight maneuver, e.g., for violating at least one operational rule set forth in the operational rules222(FIG.2).

Thus, with two identified discontinuities in the entry trajectory profile254ofFIG.6, the modified entry trajectory profile256ofFIG.7is built in accordance with inventive aspects of the present disclosure. Specifically, the modified entry trajectory profile256ofFIG.7is built according to a first build construction in response to the first sector S1being determined as the sector at block250-1(see e.g., the translated aircraft100-T and translated track angle100-T being located in the first sector S1inFIG.7). When the sector is determined as a first sector S1, the modified entry trajectory profile256is generated in accordance with a first build construction (e.g., an inbound capture construction) so that i) a capture of the holding pattern300is made at the inbound course312of the holding pattern300in a direction opposite to the inbound direction324; and ii) a tear drop pattern260is created that ends at the entry waypoint310. The modified entry trajectory profile256is generated so as to intersect the entry waypoint310a single time with a last segment of the modified entry trajectory profile256being the segment that intersects the entry waypoint310.

Accordingly, as shown inFIG.7, the modified entry trajectory profile256can include one or more segments arranged, without first intersecting the entry waypoint310, to capture the inbound course312of the holding pattern300in a direction opposite to the inbound direction324and one or more segments forming the tear drop pattern260that ends at the entry waypoint310. The one or more segments arranged to capture the inbound course312of the holding pattern300in a direction opposite to the inbound direction324include a first segment SG1, a second segment SG2, and a third segment SG3. The first segment SG1is curved to smooth the transition of the aircraft100with the second segment SG2, which stems from the first segment SG1and is straight and configured to direct the aircraft100toward the inbound course312. The third segment SG3stems from the second segment SG2and captures the inbound course312in a direction opposite to the inbound direction324at a capture point CP (or interception point). The angle of the second segment SG2relative to the inbound course312and the turn radius of the third segment SG3are selected so as to allow the aircraft100to make a smooth capture of the inbound course312at the capture point CP. The turn radii of the first and third segments SG1and SG3can be based on the current or predicted aircraft speed at the arrival to the holding pattern300, for example.

The one or more segments forming the tear drop pattern260include a fourth segment SG4, a fifth segment SG5, a sixth segment SG6, and a seventh segment SG7. The fourth segment SG4stems from the third segment SG3and follows the inbound course312in a direction opposite to the inbound direction324. The fifth segment SG5stems from the fourth segment SG4and follows the second turn320at the outbound end322of the holding pattern300and continues past an end point330of the outbound course318, turning the modified entry trajectory profile256back toward the inbound course312. At the end point330, the modified entry trajectory profile256departs from following the holding pattern300in a reverse manner. The sixth segment SG6stems from the fifth segment SG5and is a straight line segment that is configured to direct the aircraft100toward the inbound course312. The seventh segment SG7stems from the sixth segment SG6and transitions the aircraft100into the holding pattern300at the entry waypoint310. The angle of the sixth segment SG6relative to the inbound course312and the turn radius of the seventh segment SG7are selected so as to allow the aircraft100to make a smooth transition into the holding pattern300at the entry waypoint310. Particularly, in this example, the fifth and seventh segments SG5and SG7have the same turn radius, and are equal to the turn radii of the two turns of the holding pattern300. The sixth segment SG6is adjusted to be tangent to the fifth and seventh segments SG5and SG7, up to a point where the angle of sixth segment SG6relative to the inbound course312is maximum of ninety degrees (90°) (when this limit is reached, the build construction changes to the one shown inFIG.9, wherein the entry construction extends beyond the area of the holding pattern300to be able to build the tear drop ending at the waypoint310). Upon entering the holding pattern300at the entry waypoint310, the aircraft100can fly the holding pattern300.

Accordingly, the modified entry trajectory profile256is generated at block250-3in accordance with the first build construction determined at block250-2, which is the build construction type used when the first sector S1is determined as the sector at block250-1. The modified entry trajectory profile256is generated to provide a continuous and flyable entry transition into the holding pattern300despite limited airspace.

In some example aspects, after determining the build construction at block250-2, a determination can be made as to the implementation scheme for generating the modified entry trajectory profile256according to the first build construction. In some instances, for example, in generating a modified entry trajectory in accordance with a first build construction, it may be determined whether a capture of the holding pattern would be past a starting point of an inbound course of the holding pattern or whether a length of the inbound course of the holding pattern is shorter than two times a turn radius of turns of the holding pattern. In such instances, when the capture of the holding pattern would not be past the starting point of the inbound course of the holding pattern or the length of the inbound course of the holding pattern is not shorter than two times the turn radius of the turns of the holding pattern, the modified entry trajectory can be generated according to a normal capture implementation of the first build construction (e.g., as shown inFIG.7and described in the accompanying text). However, when the capture of the holding pattern would be past the starting point of the inbound course of the holding pattern or the length of the inbound course of the holding pattern is shorter than two times the turn radius of the turns of the holding pattern, the modified entry trajectory can be generated according to an extended capture implementation of the first build construction.

By way of example,FIG.8is a diagram showing a scenario where the modified entry trajectory profile256is built according to a normal capture implementation of the first build construction in response to the first sector S1being determined as the sector at block250-1(see e.g., the translated aircraft100-T and translated track angle100-T being located in the first sector S1inFIG.8; the aircraft100is physically located in the third sector S3). As shown inFIG.8, in this example, if the modified entry trajectory profile256was built according to the normal capture implementation of the first build construction, the trajectory would include a discontinuity. In this regard, the aircraft100would be unable to fly the modified entry trajectory profile256without performing an impermissible flight maneuver, if at all. The aircraft100would be unable to capture the inbound course312of the holding pattern300in a direction opposite to the inbound direction324in accordance with the normal capture implementation. To make the entry transition into the holding pattern continuous and flyable, the extended capture implementation of the first build construction can be utilized.

Accordingly,FIG.9is a diagram showing a modified entry trajectory profile256built according to an extended capture implementation of the first build construction. When the capture of the holding pattern300would be past a starting point332of the inbound course312of the holding pattern300as shown inFIG.8, the modified entry trajectory profile256is generated according to an extended capture implementation of the first build construction so that i) a capture is made past the starting point332of the inbound course312at the inbound reference line328, which extends from and is coaxial with the inbound course312, and in a direction opposite to the inbound direction324; and ii) a tear drop pattern262is created having a tear drop arc264built beyond the turn-to-inbound course (i.e., the second turn320) of the holding pattern, and the tear drop pattern262ends at the entry waypoint310. In this regard, an “extended capture” is made at the inbound reference line328in a direction opposite to the inbound direction324. The capture is made at an extended point EP1that is further away from the entry waypoint310than the starting point332of the inbound course312. Also, the tear drop arc264is shown built further away from the entry waypoint310than an arc of the second turn320. In this way, the arc of the tear drop is extended out relative to the second turn320of the holding pattern300.

The modified entry trajectory profile256ofFIG.9built according to the extended capture implementation of the first build construction can include one or more segments arranged, without first intersecting the entry waypoint310, to capture the holding pattern300past the starting point332of the inbound course312in a direction opposite to the inbound direction324and one or more segments forming a tear drop that ends at the entry waypoint310. The one or more segments arranged to capture the inbound reference line328past the starting point332of the inbound course312in a direction opposite to the inbound direction324include a first segment SG1and a second segment SG2. The first segment SG1is curved and directs the aircraft100toward the inbound reference line328. The second segment SG2, which is also curved, stems from the first segment SG1and smoothly transitions the trajectory to capture the inbound reference line328past the starting point332of the inbound course312in a direction opposite to the inbound direction324.

The one or more segments forming the tear drop that ends at the entry waypoint310include a third segment SG3, a fourth segment SG4, and a fifth segment SG5. The third segment SG3stems from the second segment SG2and follows the arc of the second turn320, albeit at an extended position or further away from the entry waypoint310than the arc of the second turn320, and then crosses the second turn320of the holding pattern300, turning the modified entry trajectory profile256toward the inbound course312. The fourth segment SG4stems from the third segment SG3and is a straight line segment that is configured to direct the aircraft100toward the inbound course312. The fifth segment SG5stems from the fourth segment SG4and transitions the aircraft100into the holding pattern300at the entry waypoint310. The angle of the fourth segment SG4relative to the inbound course312and the turn radius of the fifth segment SG5are selected so as to allow the aircraft100to make a smooth transition into the holding pattern300at the entry waypoint310. Upon entering the holding pattern300at the entry waypoint310, the aircraft100can follow the holding pattern300.

Accordingly, the modified entry trajectory profile256is generated in accordance with the extended capture implementation of the first build construction to provide a continuous and flyable entry transition into the holding pattern300despite limited airspace.

As noted previously, in some instances, in generating a modified entry trajectory in accordance with a first build construction, it may be determined whether a length of the inbound course of the holding pattern is shorter than two times a turn radius of turns of the holding pattern. When the length of the inbound course of the holding pattern is indeed shorter than two times a turn radius of the turns of the holding pattern, the extended capture implementation of the first build construction can be implemented.

For instance,FIG.10provides a diagram showing an example holding pattern300. The inbound course312has a length L1and the second turn320at the outbound end322of the holding pattern300has a turn radius R1. In this example, the length L1of the inbound course312is shorter than two times the turn radius R1of the second turn320of the holding pattern300. Accordingly, in response to this determination, a modified entry trajectory profile is generated in accordance with the extended capture implementation of the first build construction. Consequently, rather than the modified entry trajectory profile capturing the inbound course312as with a normal capture implementation of the first build construction, the inbound reference line328would be captured at an “extended point” and a tear drop would be created thereafter to direct an aircraft to the entry waypoint310, e.g., in a similar manner as shown inFIG.9. Such an implementation effectively “extends” the holding pattern300to make a continuous and flyable trajectory to enter the holding pattern300. The extended capture implementation of the first build construction may be particularly useful for instances in which the aircraft100is physically located in the third sector S3or fourth sector S4, but can also be used in some instances when the aircraft100is physically located in the first sector S1or the second sector S2.

With reference now toFIGS.11and12, an example manner is provided in which a modified entry trajectory profile can be built according to a second build construction in response to the second, third, or fourth sector being determined as the sector.FIG.11is a diagram showing an entry trajectory profile254for transitioning into the holding pattern300, with the entry trajectory profile254including at least one discontinuity.FIG.12is a diagram showing a modified entry trajectory profile256built according to a second build construction, with the second build construction being utilized in response to the third sector S3being determined as the sector at block250-1.

As shown inFIG.11, the entry trajectory profile254(e.g., built at block244inFIG.2) provides a discontinuous and unflyable trajectory to enter the holding pattern300, and thus, the entry trajectory profile254is identified as having a discontinuity. Particularly, the entry trajectory profile254is built to attempt to direct the aircraft100through or to the entry waypoint310, but as depicted, the aircraft100is too close to the entry waypoint310for this to be possible, e.g., without an impermissible flight maneuver being performed. Consequently, the first segment SG1of the entry trajectory profile254extends past the entry waypoint310. A second segment SG2of the entry trajectory profile254is built to attempt to align the aircraft100to the entry waypoint310, and a third segment SG3stemming from the second segment SG2is built to direct the aircraft100back to the entry waypoint310. In transitioning from the second segment SG2to the third segment SG3, the entry trajectory profile254provides for the aircraft100to make nearly a one hundred eighty degree (180°) turn, which would result in an impermissible flight maneuver, e.g., for violating at least one operational rule set forth in the operational rules222(FIG.2). Further, in transitioning from the third segment SG3to a fourth segment SG4, the entry trajectory profile254provides for the aircraft100to make another nearly one hundred eighty degree (180°) turn, which would result in another impermissible flight maneuver, e.g., for violating at least one operational rule set forth in the operational rules222(FIG.2). These discontinuities make the entry trajectory profile254discontinuous and unflyable.

Thus, with two identified discontinuities in the entry trajectory profile254ofFIG.11, the modified entry trajectory profile256ofFIG.12is built in accordance with inventive aspects of the present disclosure. Specifically, the modified entry trajectory profile256ofFIG.11is built according to a second build construction in response to the third sector S3being determined as the sector at block250-1(see e.g., inFIG.12, the translated aircraft100-T and translated track angle100-T being located in the third sector S3). When the sector is determined as a third sector S3(or as the second sector S2or the fourth sector S4), the modified entry trajectory profile256is generated in accordance with a second build construction so that i) a capture of the holding pattern300is made at the outbound course318of the holding pattern300in a direction with the outbound direction326; and ii) a following pattern266is created that follows the holding pattern300and ends at the entry waypoint310. The modified entry trajectory profile256is generated so as to intersect the entry waypoint310a single time with a last segment (e.g., a fifth segment SG5in the example ofFIG.12) of the modified entry trajectory profile256being the segment that intersects the entry waypoint310.

Accordingly, as shown inFIG.12, the modified entry trajectory profile256can include one or more segments arranged, without first intersecting the entry waypoint310, to capture the outbound course318of the holding pattern300in a direction with the outbound direction326and one or more segments forming the following pattern266that ends at the entry waypoint310.

The one or more segments arranged to capture the outbound course318of the holding pattern300in a direction with the outbound direction326include a first segment SG1and a second segment SG2. The first segment SG1is curved to direct the aircraft100toward the outbound course318and position the trajectory for capture of the outbound course318. The second segment SG2stems from the first segment SG1and captures the outbound course318in a direction with the outbound direction326at a capture point CP (or interception point). In this example, the modified entry trajectory profile256is generated so that, prior to the capture of the holding pattern300at the outbound course318(e.g., at the capture point CP), a segment (e.g., the first segment SG1) of the modified entry trajectory profile256crosses the outbound course318. In other examples, the modified entry trajectory profile256may not cross the outbound course318prior to capture of the holding pattern300at the outbound course318. For instance, in such examples, the modified entry trajectory profile256can capture the outbound course318without first crossing over the outbound course318. The turn radii of the first segment SG1and the second segment SG2are selected so as to allow the aircraft100to make a smooth capture of the outbound course318at the capture point CP. The turn radii of the first and second segments SG1, SG2can be based on the aircraft current or predicted speed at the arrival of the holding pattern300.

The one or more segments forming the following pattern266include a third segment SG3, a fourth segment SG4, and a fifth segment SG5. The third segment SG3stems from the second segment SG2and follows the outbound course318in a direction with the outbound direction326. The fourth segment SG4stems from the third segment SG3and follows the second turn320at the outbound end322of the holding pattern300. The fourth segment SG4can have the same radius as the radii of the two turns of the holding pattern300. The fifth segment SG5stems from the fourth segment SG4and is a straight line segment that is configured to direct the aircraft100toward the entry waypoint310along the inbound course312in a direction with the inbound direction324. Upon entering the holding pattern300at the entry waypoint310, the aircraft100can follow the holding pattern300.

Accordingly, the modified entry trajectory profile256is generated in accordance with the second build construction (i.e., the construction used when one of the second, third, or fourth sectors S2, S3, S4is determined as the sector) to provide a continuous and flyable entry transition into the holding pattern300despite limited airspace.

In some instances, in generating a modified entry trajectory in accordance with a second build construction, it may be determined whether a capture of the holding pattern would be past an ending point of an outbound course of the holding pattern. In such instances, when the capture of the holding pattern would not be past the ending point of the outbound course of the holding pattern, the modified entry trajectory is generated according to a normal capture implementation of the second build construction (e.g., as shown inFIG.12and described in the accompanying text). However, when the capture of the holding pattern would be past the ending point of the outbound course of the holding pattern, the modified entry trajectory is generated according to an extended capture implementation of the second build construction.

By way of example,FIG.13is a diagram showing a scenario where the modified entry trajectory profile256is built according to a normal capture implementation of the second build construction in response to the third sector S3being determined as the sector at block250-1(see e.g., the translated aircraft100-T and translated track angle100-T being located in the third sector S3inFIG.13; the aircraft100is physically located in the fourth sector S4). As shown inFIG.13, in this example, if the modified entry trajectory profile256was built according to the normal capture implementation of the second build construction, the trajectory would include a discontinuity. In this regard, the aircraft100would be unable to fly the modified entry trajectory profile256without performing an impermissible flight maneuver, if at all. Specifically, the aircraft100would be unable to capture the outbound course318of the holding pattern300in a direction with the outbound direction326in accordance with the normal capture implementation. To make the entry transition into the holding pattern continuous and flyable, the extended capture implementation of the second build construction can be utilized.

FIG.14is a diagram showing a modified entry trajectory profile256built according to an extended capture implementation of the second build construction. When the capture of the holding pattern300would be past an ending point336of the outbound course318of the holding pattern300as shown inFIG.13, the modified entry trajectory profile256is generated according to an extended capture implementation of the second build construction so that i) a capture is made past the ending point336of the outbound course318at an outbound reference line334, which extends from and is coaxial with the outbound course318(e.g., as shown inFIG.14), and in a direction with the outbound direction326; and ii) an extended following pattern268is built having an arc segment (e.g., a third arc segment SG3inFIG.14) and an inbound segment (e.g., a fourth segment SG4inFIG.14), the arc segment is built further beyond the turn-to-inbound course (i.e., the second turn320) of the holding pattern, and the inbound segment ends at the entry waypoint310. In this regard, an “extended capture” is made at the outbound reference line334in a direction with the outbound direction326. The capture is made at an extended point EP2that is further away from the entry waypoint310than the ending point336of the outbound course318. Also, the arc segment (e.g., the third segment SG3) of the extended following pattern268is built further away from the entry waypoint310compared to the second turn320. In this way, the arc segment is extended out relative to the second turn320of the holding pattern300.

The modified entry trajectory profile256ofFIG.14built according to the extended capture implementation of the second build construction can include one or more segments arranged, without first intersecting the entry waypoint310, to capture the holding pattern300past the outbound course318in a direction with the outbound direction326and one or more segments forming the extended following pattern268that ends at the entry waypoint310.

The one or more segments arranged to capture the outbound reference line334past the ending point336of the outbound course318in a direction with the outbound direction326include a first segment SG1and a second segment SG2. The first segment SG1is curved and directs the aircraft100toward the outbound reference line334. The second segment SG2, which is also curved, stems from the first segment SG1and smoothly transitions the trajectory to capture the outbound reference line334past the outbound course318in a direction with the outbound direction326. Prior to capture of the outbound reference line334at the extended point EP2, the modified entry trajectory profile256crosses the outbound course318. In other examples, the modified entry trajectory profile256may not cross the outbound course318or the outbound reference line334prior to capture of the outbound reference line334.

The one or more segments forming the extended following pattern268include a third segment SG3and a fourth segment SG4. The third segment SG3stems from the second segment SG2and follows the arc of the second turn320, albeit at an extended position or further away from the entry waypoint310than the arc of the second turn320. The third segment SG3ends at the inbound reference line328. The fourth segment SG4stems from the third segment SG3and is a straight line segment that follows the inbound course312along the inbound direction324. The fourth segment SG4ends at the entry waypoint310. Upon entering the holding pattern300at the entry waypoint310, the aircraft100can follow the holding pattern300.

Accordingly, the modified entry trajectory profile256is generated in accordance with the extended capture implementation of the second build construction to provide a continuous and flyable entry transition into the holding pattern300despite limited airspace.

Method

FIG.15is a flow diagram of a method400of building a modified entry trajectory profile according to example aspects of the present disclosure.

At402, the method400can include receiving instructions for an aircraft to join a holding pattern at an entry waypoint according to an entry trajectory profile. An airspace around the holding pattern can be divided into a plurality of sectors using the entry waypoint as a reference point. For instance, one or more processors of a system (e.g., a FMS) can receive instructions for an aircraft to join a holding pattern at an entry waypoint, e.g., to delay landing due to traffic congestion, poor weather, runway unavailability, emergencies on the ground, etc. The plurality of holding sectors can include a first sector, a second sector, a third sector, and a fourth sector, e.g., as shown inFIG.4. The entry trajectory can be constructed as a nominal hold entry transition defined in RTCA Document DO-236C, Appendix E, for example.

At404, the method400can include identifying a discontinuity in the entry trajectory profile. For instance, due to limited airspace or the aircraft being too close to the entry waypoint, the entry trajectory profile can include a discontinuity that would make the transition into the holding pattern discontinuous and/or unflyable and/or in violation of one or more operational rules and/or guidelines. Accordingly, the standard entry trajectory profile is “bypassed” in favor of a modified entry trajectory profile (built at406as provided below) that changes at least one aspect of the entry trajectory profile.

At406, the method400can include, in response to identifying the discontinuity in the entry trajectory profile, building a modified entry trajectory profile. For instance, the one or more processors of the system can build the modified entry trajectory profile to modify, replace, or otherwise “bypass” the entry trajectory profile. The modified entry trajectory profile can be built as set forth below.

At406-1, building the modified entry trajectory profile can include determining a sector from the plurality of sectors from which the aircraft would approach the entry waypoint with a current track angle of the aircraft moved to intersect the entry waypoint and with the aircraft pointing at the entry waypoint. For instance, with brief reference toFIG.4, the sector can be determined as the first sector S1, the second sector S2, the third sector S3, or the fourth sector S4. In some example aspects, determining the sector from which the aircraft would approach the entry waypoint if a current track angle of the aircraft was moved to intersect the entry waypoint and the aircraft was pointing at the entry waypoint can include translating the current track angle to the entry waypoint so as to render a translated track angle. The translated track angle intersects the entry waypoint and the aircraft points at the entry waypoint. The sector in which the aircraft would be located in such a translated position is determined as the sector. In some example aspects, determining the sector from which the aircraft would approach the entry waypoint if a current track angle of the aircraft was moved to intersect the entry waypoint and the aircraft was pointing at the entry waypoint can include determining a course change angle based at least in part on the translated track angle and an inbound course of the holding pattern (or an inbound reference line associated with the inbound course). The sector can be determined based at least in part on the course change angle, e.g., by way of a lookup table. For instance, the sector can be determined by correlating the course change angle to one of a plurality of predefined angle ranges, wherein each predefined angle range of the plurality of predefined angles ranges corresponds to one of the plurality of sectors.

At406-2, building the modified entry trajectory profile can include determining a build construction based at least in part on the sector determined at406-1. The build construction can be one of a plurality of possible build constructions. For instance, with brief reference again toFIG.4, when the first sector S1is determined as the sector at406-1, the build construction can be determined as a first build construction (e.g., an inbound capture construction). When the second, third, or fourth sector S2, S3, S4is determined as the sector at406-1, the build construction can be determined as a second build construction (e.g., an outbound capture construction).

At406-3, building the modified entry trajectory profile can include determining an implementation scheme for the build construction determined at406-2. The implementation scheme can be determined from one of a plurality of possible implementation schemes, which can include at least a normal capture implementation and an extended capture implementation. As one example, when a first build construction is determined at406-2in response to the first sector being determined at406-1, the first build construction can be implemented as a normal capture implementation in which an inbound course of a holding pattern is captured or as an extended capture implementation in which an inbound reference line stemming from the inbound course is captured at an “extended point” beyond the inbound course. As another example, when a second build construction is determined at406-2in response to the second, third, or fourth sector being determined at406-1, the second build construction can be implemented as a normal capture implementation in which an outbound course of a holding pattern is captured or as an extended capture implementation in which an outbound reference line stemming from the outbound course is captured at an “extended point” beyond the outbound course.

At406-4, building the modified entry trajectory profile can include generating the modified entry trajectory profile that changes at least one aspect of the entry trajectory profile based at least in part on the sector determined. That is, based on the sector determined at406-1, the build construction with which to build the modified entry trajectory profile can be determined at406-2. In some aspects, an implementation scheme for the build construction can be determined at406-3. Accordingly, the modified entry trajectory profile can be generated at406-4in accordance with the determined implementation scheme for the build construction, which, as noted, is determined based on the sector determined at406-1.

Accordingly, at406, the modified entry trajectory profile can be built so as to be a continuous and flyable path for an aircraft to enter the holding pattern at the entry waypoint. The modified entry trajectory profile can be used to build a final trajectory profile, which can ultimately be presented to the flight crew or systems of the aircraft and executed. Advantageously, the modified entry trajectory profile can provide a flyable lateral trajectory that a FCS can command the aircraft to follow without making it fly off-path. In addition, use of the modified entry trajectory can minimize or eliminate the need for flight crew intervention even when limited airspace is available. Moreover, the modified entry trajectory profile follows the standard holding pattern entry rules as much as possible, and an annunciation to the flight crew can be provided indicating that part of the standard holding pattern entry trajectory is modified or bypassed due to the limited space available. Further, increased safety levels can be provided by improving situational awareness and helping meet the airspace restrictions around the holding pattern. The situational awareness of the flight crew can be improved namely because a continuous and flyable trajectory that the aircraft actually is able to fly can be presented to them, rather than a discontinuous lateral trajectory that the aircraft cannot fly. In the past, when a discontinuous lateral trajectory has been presented to a flight crew, flight crew members have needed to develop alternative solutions for creating a flyable trajectory or have had to manually intervene, taking them away from other tasks and reducing their awareness. A continuous and flyable trajectory presented to the flight crew can eliminate the need to develop alternative solutions or intervene manually.

In the current disclosure, reference is made to various aspects. However, it should be understood that the present disclosure is not limited to specific described aspects. Instead, any combination of the following features and elements, whether related to different aspects or not, is contemplated to implement and practice the teachings provided herein. Additionally, when elements of the aspects are described in the form of “at least one of A and B,” it will be understood that aspects including element A exclusively, including element B exclusively, and including element A and B are each contemplated. Furthermore, although some aspects may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given aspect is not limiting of the present disclosure. Thus, the aspects, features, aspects and advantages disclosed herein are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

As will be appreciated by one skilled in the art, aspects described herein may be embodied as a system, method or computer program product. Accordingly, aspects may take the form of an entirely hardware aspect, an entirely software aspect (including firmware, resident software, micro-code, etc.) or an aspect combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects described herein may take the form of a computer program product embodied in one or more computer readable storage medium(s) having computer readable program code embodied thereon.