Efficient flight plans for areas with high-altitude terrain

Abstract

The present disclosure relates to efficient flight planning for areas with high-altitude terrain. Specifically, a method for determining a flight plan for an aircraft includes the following steps: determining one or more areas that intersect an initial flight path and include at least one terrain feature, the at least one terrain feature having an altitude greater than an altitude threshold; for each corresponding area: determining a flight zone based on the initial flight path and an altitude threshold line; determining one or more segments of the initial flight path, the one or more segments including one or more terrain features having an altitude greater than the altitude threshold; and determining a modified flight path for each corresponding segment by: determining multiple gradient slopes along the corresponding segment; and if any of the multiple gradient slopes conflicts with any of the one or more terrain features, moving the corresponding segment of the initial flight path in a safe descent direction.

Description

Technical Field

[0001] Various aspects described herein relate to systems and methods for determining a more efficient flight plan while maintaining safe descent options when flying over or near high elevation terrain features. Background Art

[0002] Conventional flight planning systems avoid plotting flight paths over or near high-altitude terrain features to reduce the risk posed by such terrain features in the event of an unplanned descent, such as in the event of a rapid descent in response to an unexpected cabin decompression event. This is because it is generally desirable to descend to a safe altitude as quickly as possible and then land at a nearby airport, and high-altitude terrain features may defeat these goals. As a result, flight paths in areas with high-altitude terrain features tend to be longer and less direct, which significantly affects the efficiency of flight operations. For example, longer flight paths mean increased fuel use and increased wear on aircraft components, resulting in overall higher operating costs, higher environmental impacts, and lower aircraft operational availability. In addition, longer flight paths mean longer flight times for customers, which leads to lower satisfaction.

[0003] Therefore, there is a need for improved systems and methods for determining a more efficient flight plan while maintaining safe descent options when flying over or near high altitude terrain features. Summary of the invention

[0004] In a first aspect, a method for determining a flight plan of an aircraft from an origin to a destination is provided, the method comprising the following steps: determining one or more regions intersecting an initial flight path and including at least one terrain feature, the at least one terrain feature having an altitude greater than an altitude threshold; for each corresponding region of the one or more regions, performing the following operations: determining a flight zone within the corresponding region based on the initial flight path and an altitude threshold line, wherein the altitude threshold line indicates a portion of the corresponding region in which all terrain is below the altitude threshold along a safe descent direction of the corresponding region; determining one or more segments of the initial flight path in the corresponding region, the one or more segments including one or more terrain features having an altitude greater than the altitude threshold; and determining a modified flight path for each corresponding segment of the one or more segments of the initial flight path in the corresponding region by: determining a plurality of gradient descents from a plurality of locations along the corresponding segment and from the estimated cruising altitude to the altitude threshold based on an estimated descent time from an estimated cruising altitude to the altitude threshold and moving the corresponding segment of the initial flight path in a safe descent direction if any of the plurality of gradient declines would conflict with any of the one or more terrain features along the corresponding segment, wherein the modified flight path of the corresponding area is between the initial flight path and an altitude threshold line within a flight zone of the corresponding area.

[0005] Other aspects provide a processing system that performs the aforementioned methods and those described herein; a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of the processing system, cause the processing system to perform the aforementioned methods and those described herein; a computer program product specifically implemented on a computer-readable storage medium comprising code that performs the aforementioned methods and those further described herein; and a processing system comprising means for performing the aforementioned methods and those further described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The drawings depict aspects of the one or more embodiments and therefore should not be considered to limit the scope of the disclosure.

[0007] Figure 1 An initial flight path is depicted across the area of ​​interest and over an area of ​​high terrain.

[0008] Figure 2A A view depicting the gradient ramp down from cruising altitude to altitude threshold over an area of ​​high terrain.

[0009] Figure 2B yes Figure 2A A top-down view of the image and depicts the gradient drop through the high terrain area to the height threshold.

[0010] Figure 3 Aspects of a system for planning a flight of an aircraft are described.

[0011] Figure 4 Depicted from Figure 3 Flowcharts of various aspects and operations of embodiments of a direct-to determination subsystem.

[0012] Figure 5 depicts an overhead view of the flight planning process used to determine a modified flight path and is Figure 4 The result of the processing described in .

[0013] Figure 6 An overhead view of various flight paths over or near high terrain areas is depicted, and the results of the guidance direction determination subsystem are presented.

[0014] Figure 7 A view depicting various gradient declines from cruising altitude to an altitude threshold over or near an area of ​​high terrain.

[0015] Figure 8 Depicted from Figure 3 Various aspects of embodiments and operational flowcharts of an emergency destination determination subsystem.

[0016] Fig. 9 A flight path with safe gradient descents to multiple landing sites near high altitude terrain features is depicted.

[0017] Fig.10 An example method of determining a flight plan for an aircraft from an origin to a destination is described.

[0018] Fig.11 An example processing system of a system for planning a flight plan for an aircraft is depicted.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0020] Aspects of the present disclosure provide systems and methods for determining a more efficient flight plan while maintaining safe descent options when flying over or near high elevation terrain features.

[0021] A flight plan is typically a plan submitted by a pilot or flight dispatcher to a local Air Navigation Service Provider (e.g., the FAA in the United States) prior to departure, which indicates, among other information, the planned route or flight path of the aircraft. In some cases, a flight plan may be formatted according to a specific standard, such as ICAO (International Civil Aviation Organization) Doc 4444. A flight plan may typically include information such as the following: departure and arrival points, flight paths between departure and arrival points, estimated en route time, alternate airports in case of bad weather, flight type (e.g., instrument flight rules (IFR) or visual flight rules (VFR)), pilot information, number of people on board, and information about the aircraft itself, among others. In some cases, the flight path in a flight plan may include a list of waypoints (e.g., defined by latitude and longitude) that the aircraft intends to traverse in sequence as part of the flight plan.

[0022] Routing types used in flight planning may include, for example, airway routing, navaid routing, and direct routing, and a flight path may be composed of segments of different routing types. Airway routing may typically follow a predefined path that is analogous to a three-dimensional highway for the aircraft and includes rules governing airway routing that cover altitude, airspeed, and requirements for entering and leaving airways. Navaid routing occurs between navigational aids that are not always connected by airways. Direct routing occurs when one or both of the route segment endpoints are at a latitude / longitude that the navaid cannot locate.

[0023] Conventional flight plans steer clear of high altitude terrain features to ensure that the aircraft can easily descend quickly to a safe altitude at any point along the flight path in the event of an unexpected flight problem (such as rapid cabin depressurization). However, unnecessary indirect flight paths can lead to increased fuel use, increased wear on aircraft components, higher operating costs, higher environmental impact, and lower aircraft operational availability, among other things. Conventional flight plans also use a static list of airports to use in the event of an emergency landing.

[0024] The embodiments described herein improve upon conventional flight planning methods by taking into account a wide range of factors in order to plan a more efficient and equally safe flight path. For example, the embodiments described herein take into account the operating characteristics of different aircraft (e.g., maximum descent speed, maximum speed over the ground, etc.), current wind conditions in areas with high altitude terrain features, and other factors to generate a more direct and therefore more efficient flight path.

[0025] More specifically, the embodiments described herein may start with the most direct flight path between an origin and a destination. In some cases, the most direct flight path may be a great circle flight path between the origin and the destination, while in other cases, the most direct flight path may be diverted to avoid certain areas for specific reasons (such as political, weather-related, etc.). A great circle flight path is the shortest distance between two points on the surface of a sphere.

[0026] Then, embodiments described herein identify a segment along the most direct flight path that passes through a high altitude terrain region, which segment may include, for example, high altitude terrain features (e.g., features having an altitude above a certain threshold, such as 10,000 feet). In some cases, the altitude threshold may be an absolute threshold, such as an area containing terrain features (e.g., mountain peaks) having an altitude above the threshold. In other cases, the altitude threshold may be selected based on a minimum obstacle clearance above any terrain feature. For example, with a minimum obstacle clearance of 2,000 feet and an altitude threshold of 10,000 feet, any terrain feature above 8000 feet will exceed the altitude threshold including the minimum obstacle clearance (e.g., altitude 8001 feet + obstacle clearance 2000 feet = 10001 feet).

[0027] For each identified flight segment, a flight zone can be determined based on the initial flight path, safe descent direction, and altitude threshold line. An optimal flight path within the flight zone for the segment can then be determined by considering possible gradient declines, known terrain features, aircraft performance, and local weather. The resulting modified flight path maintains the safety attributes of a conventional flight plan while allowing for a modified flight plan that is significantly more efficient than a conventional flight plan, which can completely avoid high terrain areas.

[0028] Therefore, the systems and methods described herein improve conventional flight planning methods by using aircraft-specific information and weather to calculate gradient slopes at multiple locations along each leg. If all gradient slopes do not conflict with terrain features or violate minimum obstacle clearance thresholds (such as Figure 2AIf the flight path is close to the high altitude terrain features, the flight path is moved closer to the great circle flight path (which may pass through high terrain areas), and the process is repeated. If at least one gradient drop conflicts with the terrain features or violates the minimum obstacle clearance threshold, the flight segment is moved away from the great circle flight path. This iterative process makes the flight path as close to the high altitude terrain features as possible while ensuring a safe flight plan and produces a shorter flight path compared to conventional methods.

[0029] Furthermore, the embodiments described herein improve conventional flight planning methods by using information about nearby airports, such as runway length and on-site weather, to determine a suitable emergency destination in the event that an aircraft must land while in flight. Emergency destinations are determined for each gradient drop and can be updated while in flight.

[0030] Examples of flight paths over or near high altitude terrain features

[0031] Figure 1 An initial flight path 100a of an aircraft 104 is depicted traversing an area of ​​interest 106 and passing over a high terrain area 108a. In this example, the area of ​​interest 106 is represented as a projection on a map with a high terrain area 108, wherein the high terrain area 108 includes one or more features above an altitude threshold, which will be referenced Figure 2A These characteristics are further described (e.g., altitudes at or above the altitude threshold 212). The high terrain region 108 is bounded by an altitude threshold line 124 that marks the beginning of the altitude threshold. For example, the altitude threshold line 124 marks the boundary of the high terrain region 108a. Therefore, based on the value of the threshold (e.g., 10,000 feet), the altitude threshold line (e.g., 124) is fixed for each high terrain region (e.g., 108).

[0032] The flight path 100a can be initially generated as the most direct route between the starting point and the destination point. In some cases, the initial flight path 100a can be as close as possible to the actual shortest path between the starting point and the destination, such as a path approximated by a great circle path. However, in view of the air route structure, wind conditions, overflight charges and other factors that vary from country to country, the initial flight path may often deviate from the great circle path. In this example, the initial flight path 100a passes through the area of ​​interest 106 and flies over the high terrain area 108a.

[0033] Conventional flight planning methods avoid the area of ​​interest 106 entirely in order to avoid high terrain areas (e.g., 108) within the area of ​​interest 106. For example, flight path 100b illustrates an example of a flight path generated according to conventional methods. Unlike conventional methods, and as further described herein, initial flight path 100a may be modified to safely traverse the area of ​​interest 106 and fly over or near the high terrain areas 108 while maintaining the same safety margin as flight path 100b. In some embodiments, as further described below, initial flight path 100a may be broken down into multiple segments, some of which may be moved during flight planning to safely navigate the area of ​​interest 106 without having to fly completely around the area of ​​interest, as flight path 100b does.

[0034] For example, the initial flight path 100a may be divided into multiple segments based on each intersection of the flight path 100a with a high terrain area (e.g., 108a). Thus, in this example, the first segment 102a in the initial flight path 100a begins outside the area of ​​interest 106 and terminates where the flight path 100a intersects the altitude threshold line 124. Then, the second segment 102b is defined as the portion of the flight path 100a between the end of the segment 102a and where the flight path 100a intersects the altitude threshold line 124 again. Next, the third segment 102c is defined as the portion of the flight path 100a between the end of the segment 102b and the end of the flight path outside the area of ​​interest 108a at the final destination. It is worth noting that this is just one example, and in other examples, the segments may be defined in alternative ways, such as defining more than one segment per each high terrain area, or defining additional segments that start and / or terminate at intersections with the area of ​​interest. In some implementations, flight segments are defined only within the area of ​​interest that intersects the initial flight plan.

[0035] Once broken down into multiple segments, the individual segments of the initial flight path 100a may be modified for safety. As discussed above, a conventional flight plan may avoid the area 106 entirely (e.g., via flight path 100b), which can significantly extend the flight path and therefore increase flight time, fuel use, etc. In contrast, the embodiments described herein may adjust the segments of the initial flight path 100a within the area of ​​interest 106 and / or high terrain area 108 to minimize the risk from high altitude terrain features (e.g., 108a). The ability to fly over these areas results in the use of a shorter flight path than a conventional flight plan (e.g., 100b), thereby advantageously reducing operating costs, reducing environmental impact, and increasing aircraft operational availability. Figures 3 to 10 Various aspects of improving flight planning are described in more detail.

[0036] Determine the safe gradient of the flight path

[0037] As briefly described above, one aspect of creating a safe flight plan is to determine safe descent directions for various areas in the flight path. For example, in an area with high altitude terrain features to the north of the flight path, the safe descent direction may be in a southerly direction. This is because an emergency or other unplanned descent is preferably performed as quickly and as safely as possible. During such a descent, high altitude terrain features in the flight path range may pose a hazard.

[0038] Figure 2A and Figure 2B Different views of a gradient drop 214 through a high terrain region 208 to an altitude threshold 211 are depicted. The high terrain region 208 is an area that includes terrain features 210 that are above an altitude threshold 212.

[0039] A descent gradient is typically a three-dimensional path from a first altitude, such as a cruising altitude, to a second altitude, such as a safety altitude (e.g., altitude threshold 211). A descent gradient may be flown in the event of an unexpected event, such as an unexpected cabin decompression, a medical problem on board the aircraft, or a mechanical problem with the aircraft, etc.

[0040] In particular, Figure 2A Depicted in high terrain area 208 (e.g., according to Figure 1 108a) from the cruising altitude to the altitude threshold 211. In this example, the aircraft is flying a certain flight path (e.g., Figure 2B ), and the aircraft must quickly descend to an altitude threshold 211.

[0041] In response to this event, the aircraft may quickly change heading according to the safe descent direction 218 and begin a descent along the gradient ramp 214 to the altitude threshold 211. In some embodiments, the safe descent direction may be determined as part of the flight plan process, or in other embodiments, the safe descent direction may be determined separately. In some cases, the safe descent direction may be based on current flight conditions.

[0042] In this example, altitude threshold 211 is depicted as being higher than altitude threshold 212. In other examples, the altitude threshold (e.g., 211) is lower than the altitude threshold (e.g., 212) or is at the same altitude as the altitude threshold. In some examples, altitude threshold 211 is at an altitude at which atmospheric pressure allows aircraft passengers to breathe without supplying oxygen, such as 10,000 feet above mean sea level. In one example, altitude threshold 212 is approximately 10,000 feet, but may be at a different altitude in other examples. As described above, altitude threshold 212 may describe a minimum obstacle clearance, such as 2,000 feet in some examples.

[0043] Figure 2A Also depicted is an example of a minimum obstacle clearance line 220, which is a required minimum standoff distance from terrain feature 210, such as may be set by an operator, based on aircraft characteristics, or provided by a civil aviation organization such as ICAO. In one example, altitude threshold 211 is at an altitude above altitude threshold 212 that is approximately the minimum standoff distance or minimum obstacle clearance threshold.

[0044] It is worth noting that aspects of the gradient ramp down 214, such as the slope of the gradient ramp down, may vary depending on the characteristics of the aircraft making the descent, such as the maximum safe vertical speed of the aircraft, and environmental conditions, such as wind direction. Typically, the maximum safe vertical speed of an aircraft is the fastest speed at which the aircraft can safely descend within the flight envelope of safe operations, such as approximately 6,000 ft / min (feet per minute) to 7,000 ft / min for a certain aircraft, for example. However, the maximum safe vertical speed may vary depending on a variety of factors, including aircraft type or model, weather conditions, and other factors.

[0045] In some embodiments, once the aircraft is at the altitude threshold 211, an alternate or emergency landing destination may be selected, as described in reference to Figure 3 , Figure 8 and Fig. 9 discussed in more detail.

[0046] Figure 2B yes Figure 2A 206 and shows that the height threshold (e.g., from Figure 2A The height threshold 211) has a gradient drop 214. Figure 2B As depicted, following an unexpected event 216 along flight path 200, a turn is made in a safe descent direction 218. Altitude threshold line 224 marks the Figure 1The altitude thresholds described in (eg, altitude threshold line 124) are at the beginning of terrain features at the same altitude.

[0047] Example application for determining flight plans over or near high altitude terrain features

[0048] Figure 3 Aspects of a system 300 for planning a flight plan 302 for an aircraft are depicted, and in particular, planning a flight plan (e.g., 302) that includes a flight path that traverses over or near a high terrain area as described above. The system 300 may be implemented on a device used for flight planning (such as a computer, phone, or tablet) or on aircraft avionics (such as a flight management system). The system 300 or aspects of the system may be implemented onboard and / or offboard the aircraft.

[0049] For example, in an off-board implementation, system 300 communicates with an aircraft during flight via a data connection, such as a ground-based wireless data connection or a space-based data connection, to update flight plan 302. Additionally, flight plan 302 may be modified based on emerging conditions, such as local weather, before the aircraft takes off, while the aircraft is in flight, or both.

[0050] In this example, as described above, the direct-to determination subsystem 304 uses factors affecting flight 306 to determine a flight path with a safe gradient drop over a high terrain area. Then, the flight planning engine subsystem 308 generates a flight plan 302 based on the flight path with a safe gradient drop, and the emergency destination determination subsystem 310 uses factors affecting landing 312 to determine a suitable emergency destination along the flight path with a safe gradient drop. In some embodiments, the suitable emergency destination may be information included in the flight plan 302.

[0051] In this example, factors 306 that affect flight include: great circle origin and destination 306a, area of ​​interest 306b, maximum safe vertical speed 306c for aircraft type, overall escape direction per area 306d, wind forecast per altitude (including speed and vector) 306e, maximum operating speed of aircraft per altitude (e.g., V mo ) 306f, minimum obstacle clearance per area 306g, and terrain data including altitude data 306h. In other examples, other and additional factors may be considered.

[0052] As described above, the great circle origin and destination 306a is a great circle flight path from the origin to the destination. This is the theoretically optimal flight path, but may not be feasible for several reasons including: high altitude terrain features, air route structure, wind conditions, and flight airspace costs that vary from country to country. Therefore, the great circle flight path can be used as a baseline for comparing the initial flight path.

[0053] Areas of concern 306b include various areas that may affect the flight path, such as areas with high altitude terrain, severe weather, political safety issues, and other factors, as described above.

[0054] The maximum safe vertical speed 306c for the aircraft type is the fastest speed at which the aircraft can safely descend, as described above. This value will typically vary depending on the type or model of aircraft, and will be based, inter alia, on the performance characteristics of the aircraft, the manufacturer's recommended flight envelope, and other factors.

[0055] The overall escape directions per region 306d is a list of recommended directions for descent in situations where a rapid descent is required (such as the above-mentioned contingency). The directions may vary from region to region depending on the terrain or other factors that affect the descent. For example, if the aircraft is flying with mountainous terrain on its left side and flat terrain on its right side, the overall escape direction is likely to be to the right because there are no terrain features to contend with during the descent in that direction. In one example, the escape directions are predefined based on the region that includes the area of ​​interest. In other examples, these escape directions are calculated using the flight path, aircraft speed, underlying terrain, and other data sources. The calculations can be performed during flight planning or in real time during flight.

[0056] The wind forecast per altitude 306e includes data on wind direction and wind speed over time for multiple altitudes, including predictions for future wind conditions. Data may be provided for each region and each discrete altitude level (or altitude range). In some examples, the wind forecast per altitude 306e is initially determined during flight planning and may then be updated during flight based on changing wind conditions.

[0057] Maximum aircraft operating speed per altitude 306 is a list of maximum aircraft speeds at various altitudes. This value will vary based on the type or model of aircraft, similar to the maximum safe vertical speed 306c for the aircraft type.

[0058] Minimum obstacle clearance per region 306g is a list of minimum separation distances from terrain features that the aircraft must maintain. Separation distances may vary from region to region and must generally be observed even when performing a rapid descent.

[0059] The terrain data 306h is a three-dimensional data set describing the surface of the earth. The terrain data 306h can be used to determine the area of ​​interest, including high terrain areas above the altitude threshold. In addition, the minimum obstacle clearance threshold can be based on the terrain data 306h as a reference for obstacle characteristics.

[0060] Factors 306 that affect flight may be determined before the flight, during the flight, or both. Factors 306a to 306h may be derived from various data sources. Notably, factors 306a to 306h that affect flight are only examples, and in other embodiments, other factors for flight planning may be included. For example, a no-fly zone data source may be used to prevent flights over restricted airspace or other ranges for political reasons. In other examples, an initial flight path (which may be set by an operator or provided by a civil aviation organization such as ICAO) may be used as a starting point for determining a modified flight path, wherein the initial flight path is not a great circle flight path.

[0061] In this example, factors 312 affecting landing include airport information 312a, airport visibility report 312b, airport wind condition report 312c, and weather data 312d.

[0062] Airport information 312a is a list of airports around the world, including, for example, runway number, length, direction, and status. Airport information 312a may include public and private airports, as well as military bases in some examples. If an unexpected event occurs (such as an unexpected cabin decompression), airport information 312a may be used to determine potential emergency destinations for an aircraft.

[0063] Airport visibility report 312b includes data related to visibility conditions at the airport. Visibility reports can generally be provided by a data service (provider) and can be updated at a fixed interval. In some embodiments, visibility report 312b can be provided as real-time data, for example, based on a sensing system at the airport.

[0064] The airport wind report 312c includes data related to the wind conditions at the airport. For example, the airport wind report 312c may include wind speed, wind direction, variability, and other wind characteristics. The airport wind report 312c may typically be provided by a data service (business) and may be updated at a fixed interval. In some embodiments, the airport wind report 312c may be provided as real-time data, for example, based on a sensing system at the airport.

[0065] Weather data 312d may include data related to weather, including weather at and around an airport more generally. Weather data may include current and forecasted weather conditions, including temperature, humidity, cloud layering, and other weather conditions. Weather data 312d may be provided by various means including sensors on the aircraft, sensor reports from other aircraft, reports from air traffic control, and sensor readings from ground-based sensors shared with the aircraft directly or through other channels, such as through air traffic control.

[0066] Factors 312 affecting landing can be estimated before flight and updated during flight, and can include different combinations of previously discussed data sources or additional data sources. Factors 312a to 312d can be derived from various data sources. It is worth noting that factors 312a to 312d are just some examples, and in other embodiments, other factors for flight planning can be included.

[0067] The subsystems including the guidance direction determination subsystem 304 and the emergency destination determination subsystem 310 may be provided by a single system in some embodiments, or may be provided by multiple cooperating systems in other embodiments. For example, data may be exchanged through an application programming interface (API) and data channels established between subsystem components. In some embodiments, each subsystem may operate individually and independently of one another.

[0068] For example, one or more of the guidance direction determination subsystem 304, the flight planning engine 308, and the emergency destination determination subsystem 310 can be implemented in an off-board device, such as at an airline's operations center. In some embodiments, one or more of these subsystems can be implemented on a mobile device (such as a laptop or tablet computer) or other computing device that can be moved around. For example, subsystems 304, 308, and 310 can be part of an integrated flight planning software suite that can be installed on a tablet computing device. In some embodiments, subsystems 304, 308, and 310 can be implemented as a client-server software system, where the server performs the main processing and the client receives data processed by the server (such as on a portable electronic device).

[0069] Example guidance direction determination

[0070] Figure 4 Depicted as reference Figure 3 A flow chart depicting various aspects of an embodiment and operation of a guidance direction determination subsystem 304 is provided, including inputs such as factors affecting flight 306 .

[0071] In this example, step 408 uses the great circle origin and destination 306a flight paths and the area of ​​interest 306b to derive an altitude threshold line (e.g., Figure 2B The altitude threshold line 224 and Figure 1 High terrain areas in 108 and Figure 2B high terrain area 208).

[0072] Then, step 410 divides the great circle origin and destination 306a flight paths over these areas into multiple segments, so that whenever the great circle origin and destination 306a flight paths are different from the above, the flight paths of the great circle origin and destination 306a are divided into multiple segments. Figure 1 When the described altitude threshold lines intersect, a new flight segment is created. In other examples, steps 408 and 410 use a flight path different from the great circle origin and destination 306a flight path, such as an initial flight path.

[0073] Step 412 uses the maximum safe vertical speed 306c for the aircraft type to calculate the descent time, which is the time it takes for the aircraft to descend from a cruising altitude (such as a flight path) to an altitude threshold. For example, if the maximum safe vertical speed 306c for the aircraft type is 6,000 ft / min, and the vertical distance between the cruising altitude and the altitude threshold is 25,000 feet, then step 412 will be approximately 4.17 minutes. In some examples, an estimated cruising altitude may be used based on estimated or predicted conditions such as weather, turbulence, or air traffic. Then, step 412 calculates an estimated descent time. However, the actual cruising altitude may be different from the estimated cruising altitude based on actual conditions and changing conditions during flight.

[0074] In this example, step 414 uses the overall escape direction per region 306d and the wind condition forecast per altitude 306e to determine whether the aircraft is facing a headwind or a tailwind, which will affect the gradient drop, such as Figure 6 For example, if the general escape direction 306d for each area is southward, and the wind condition forecast 306e for each altitude is from south to north, then step 414 will be headwind for all altitudes.

[0075] Step 416 uses the maximum operating speed of the aircraft at each altitude (e.g., V mo ) 306f, the wind condition forecast for each height 306e and the result of step 414, to calculate the maximum operating velocity over ground (for example, V mog). The maximum operating speed over ground is equal to the sum of the maximum operating speed and the wind speed, where the wind speed is positive if there is a tailwind and negative if there is a headwind, and is calculated for each altitude. For example, if the maximum operating speed is 390MPH and there is a 35MPH tailwind, then the maximum operating speed over ground is 425MPH. For the same example, but with a headwind, the maximum operating speed over ground is 355MPH.

[0076] Step 418 determines the distance traveled over the ground using the result of step 414 and the result of step 416. For example, if the maximum operating speed over the ground is 425 MPH and the time to descend to the altitude threshold is 4.17 minutes, then the aircraft has traveled approximately 29.5 miles over the ground.

[0077] Steps 414, 416, and 418 are dependent on altitude, and therefore, are typically calculated for multiple altitudes in block 420. In one example, block 420 uses altitude increments of 1,000 feet for each determination.

[0078] Block 422 uses the results of block 420 (such as the different distances from step 418) along with the cruise altitude and altitude threshold, and calculates the gradient ramp down for multiple locations along each segment from step 410. Block 422 begins its calculation at the beginning of the segment, and moves along the segment, e.g., in fixed increments, until the end of the segment is reached.

[0079] Step 424 uses the minimum obstacle clearance per region 306g and terrain data 306h to calculate the lowest altitude that the aircraft can fly above the terrain feature. The region used here covers the area in the area of ​​interest 306b. For example, if the minimum obstacle clearance threshold is 2,000 feet and the terrain feature is 11,000 feet, then the aircraft must fly at an altitude of at least 13,000 feet.

[0080] Step 426 uses the result of block 422 and the result of step 424 to determine whether any of the gradient declines along the flight segment conflicts with a terrain feature or violates a minimum obstacle clearance threshold. The operation of the guidance direction determination subsystem 304 is repeated until a modified flight path is determined. In some cases, all flight segments overlap with a great circle flight path (which is the optimal flight path), and the modified flight path is the great circle flight path.

[0081] For example, if at least one of the gradient declines of the flight segment conflicts with a terrain feature or violates a minimum obstacle clearance threshold in step 426, then at step 428a, the flight segment is moved away from the great circle origin and destination 306a flight path (e.g., in a safe descent direction) by a fixed increment, and the operation of the guidance direction determination subsystem 304 is repeated as described above. However, if at step 426, none of the gradient declines of the flight segment conflicts with a terrain feature or violates a minimum obstacle clearance threshold, then at step 428b, the flight segment is moved closer to the great circle origin and destination 306a flight path by a fixed increment, and the operation of the guidance direction determination subsystem 304 is repeated as described above. The fixed increment may be, for example, in miles or latitude and / or longitude, etc. Notably, this generally has the effect of shortening the overall flight path and making it more efficient, as described above and as described below with reference to Figure 5 and Figure 6 More detailed examples.

[0082] If the result of the operation of the guidance direction determination subsystem 304 for the flight segment fluctuates between steps 428a and 428b, the problematic flight segment can be moved toward or away from the great circle flight path in smaller increments until the process in block 430 finds a better optimal solution. Otherwise, the most recent result of step 428b can be used as the solution. The process is repeated for all flight segments in block 430.

[0083] Example modified flight path

[0084] Figure 5 A top view of the flight planning process used to determine the modified flight path 500b is depicted and is Figure 4 The result of the processing described in .

[0085] In this example, the initial flight path 500a passes through the area of ​​interest 506, and when the initial flight path intersects the altitude threshold line 524, a first flight segment 502a is created. The altitude threshold line 524 demarcates the high terrain area 508. Here, the initial flight path 500a is a great circle flight path, but in other examples, it can be based on an alternative initial flight path generation technique. At least one gradient drop of the first flight segment 502a conflicts with a terrain feature or violates a minimum obstacle clearance threshold. Therefore, the first flight segment 502a then moves incrementally away from the great circle flight path (e.g., the initial flight path 500a) toward the escape direction 518 and becomes the second flight segment 502b.

[0086] The same process is repeated for the second flight segment 502b and the third flight segment 502c, and so on, until the gradient slope of the nth flight segment 502d is found to not conflict with the terrain features or not violate the minimum obstacle clearance threshold, thereby generating the modified flight path 500b. In some examples, the modified flight path 500b can be determined before the nth flight segment 502d. In another example where the initial flight path 500a is not a great circle flight path, the gradient slope of the first flight segment 502a does not conflict with the terrain features or does not violate the minimum obstacle clearance threshold, so the first flight segment 502a is moved to be close to the great circle flight path, and the process is repeated until a better optimal solution is found.

[0087] In other examples, a flight segment is defined as connecting multiple waypoints that are independent of the altitude threshold line 524. However, the same flight planning process is used to determine the modified flight path.

[0088] Figure 6 Depicts overhead views of various flight paths over or near high terrain areas and presents Figure 4 The result of the guidance direction determination subsystem 304 in.

[0089] In this example, aircraft 604 is near a high terrain area that includes a safe flight zone 624 and an unsafe flight zone 626. Safe flight zone 624 is an area above an altitude threshold where all gradient declines do not conflict with terrain features or violate a minimum obstacle clearance threshold. Unsafe flight zone 626 is an area above an altitude threshold where at least one gradient decline conflicts with a terrain feature or violates a minimum obstacle clearance threshold and, therefore, is unsafe for aircraft 604 to travel.

[0090] In this example, three flight paths are presented. As described above, great circle flight path 600a is the most direct route to the destination. In this example, great circle flight path 600a is also the initial flight path (e.g., Figure 4 4 and 5). However, in other examples, it may be only the initial flight path (rather than the great circle flight path). Although not shown, the unsafe flight zone 626 may extend northward beyond the great circle flight path 600a, but here, the safe descent direction is southwest, and the safe flight zone and the unsafe flight zone are depicted along this direction. Therefore, the aircraft 604 cannot fly the great circle flight path 600a because, in this example, the aircraft 604 passes through the unsafe flight zone 626 and it is impossible to safely descend from all parts of the flight path.

[0091] The conventional way to solve the problem of the large arc flight path 600a is to turn the flight path around the entire range to avoid flying completely over the high terrain area. A conventional flight path 600c is obtained, which avoids any part of passing through the unsafe flight area 626 and the safe flight area 624, resulting in increased flight distance, time and cost.

[0092] An improved method for determining alternative flight paths is to use environmental conditions and aircraft data (e.g. Figure 4 The factors affecting flight in the 306) are used to determine an equally safe but more direct flight path. This is achieved by evaluating the gradient declines originating from the cruising altitude at the flight path in question and ensuring that all gradient declines originate from outside the unsafe flight zone 626.

[0093] Gradient slopes are evaluated for multiple locations along each segment in the flight path, such as a first segment 602a and a second segment 602b defined by multiple waypoints. If at least one gradient slope of any segment originates from an unsafe descent zone 626, the segment is moved, such as in Figure 4 as described in block 430 of .

[0094] The result of this process is a modified flight path 600b, which is an improvement over the conventional flight path 600c because it is more direct and therefore shorter. In this example, the modified flight path 600b passes through the safe flight zone 624 while avoiding the unsafe flight zone 626, and is based on Figure 3 An implementation of the resulting flight plan (e.g., flight plan 302).

[0095] Ranges 624 and 626 are bounded by altitude threshold line 624a and unsafe threshold line 626a, respectively. Altitude threshold line 624a is fixed for a region (similar to the Figure 2B 224 in the altitude threshold line 224), and the unsafe threshold line 626a depends on environmental conditions and aircraft data (e.g., from Figure 4 Factors affecting flight 306). Therefore, the unsafe threshold line 626a is variable for each high terrain area according to conditions, which further improves the safety of the method of determining a flight path described herein.

[0096] For example, when flying a southwesterly gradient descent, a northerly wind 628 causes the aircraft to have a headwind. Given a maximum safe descent rate, the headwind reduces the maximum ground speed and thus reduces the distance that the aircraft 604 can travel over the ground during the gradient descent (similar to Figure 44. The modified flight path 600b is located between the altitude threshold line 624a and the unsafe threshold line 626a. The modified flight path 600b is located between the altitude threshold line 624a and the unsafe threshold line 626a, and between the initial flight path 600a and the conventional flight path 600c.

[0097] Figure 7 Depicted are views of various gradient ramps ( 714 a - 714 c ) from a cruising altitude to an altitude threshold 711 over or near a high terrain area 708 .

[0098] In this example, the aircraft is flying a flight path when an unexpected event 716a occurs and the aircraft must make a rapid descent. The route to the altitude threshold 711 is unsafe for the gradient descent 714a because the route violates the minimum obstacle clearance threshold, as represented by the minimum obstacle clearance line 720. Therefore, the corresponding flight path is unsafe and passes through the unsafe flight zone 726 as shown.

[0099] Moreover, normal gradient ramp down 714c results from unexpected event 716c that occurs on the normal flight path outside of ranges 726 and 724, and modified gradient ramp down 714b results from unexpected event 716b that occurs on the flight path through safe flight region 724. Ranges 726 and 724 represent areas having terrain above altitude threshold 712, as previously described in Figure 6 In two gradient descents 714b and 714c, the aircraft safely descends to the altitude threshold 711.

[0100] In this example, the most direct flight path passes through unsafe flight zone 726 (similar to Figure 6 The flight path corresponding to the unexpected event 716b is a modified flight path (e.g., from Figure 6 600b), and is Figures 4 to 6 . Notably, the modified flight path is made as close to the most direct flight path as safely possible while remaining in the safe flight zone 724. Thus, the resulting modified gradient ramp 714b is close to but does not violate the minimum obstacle clearance threshold.

[0101] In other examples, modified gradient ramp down 714b is derived from a cruising altitude at any location within safe flight zone 724. In this example, ranges 726 and 724 represent ranges of potential flight paths at particular altitudes, and may be represented differently in other examples.

[0102] Example Emergency Destination Determination

[0103] Figure 8 Describes the previous Figure 3 A flow chart of various aspects and operations of an embodiment of an emergency destination determination subsystem 310 is depicted in FIG. 3 , including inputs such as factors affecting landing 312 .

[0104] In this example, step 816 uses gradient ramp 814 and airport information 312a to identify a list of emergency destinations within a threshold distance (e.g., radius) from the aircraft. Gradient ramp 814 is a plurality of gradient ramps derived from the cruising altitude of the flight path, and airport information 312a is a list of all airports. Thus, step 816 identifies airports at different locations along the flight path and gradient ramp within the range of the aircraft, and may change with the location of the aircraft. In some examples, a modified flight path is used as the flight path, and therefore, step 816 calculates the distance from the modified flight path to the one or more emergency destinations.

[0105] In this example, step 818 uses the airport visibility report 312b and the airport list from step 816 to filter out emergency destinations that do not have sufficient visibility for visual flight rules (VFR) landings from the list in step 816. In other examples where it is not necessary for the aircraft to land under VFR conditions (e.g., landing under instrument flight rules conditions), step 818 is not used or bypassed.

[0106] Step 820 uses the airport wind condition report 312c (such as wind speed and direction) and the airport list from step 818 to filter out emergency destinations that have wind conditions that are too difficult for an aircraft to land. For example, cross winds of 33 mph to 40 mph or more can prevent some aircraft from landing. The threshold for wind conditions depends on several factors, including the aircraft type or model and the runway condition (e.g., wet or dry).

[0107] Step 822 uses weather data 312d (such as actual wind conditions in the air) and the list of airports from step 820 to filter out emergency destinations that are outside the range of the aircraft given a time threshold for the flight time. The time threshold is typically the amount of time the aircraft can travel after completing the emergency descent, and in some examples, is no more than about 30 minutes. In some examples, using the information from the guidance direction determination subsystem (e.g., Figure 4 The time threshold is determined based on additional information (such as the maximum operating speed) from the guidance direction determination subsystem 304 in the system.

[0108] In this example, after steps 816, 818, 820, and 822 are completed, the emergency destination determination subsystem 310 provides the destination to be determined in the flight plan (e.g., Figure 3 The emergency destination determination subsystem 310 may be part of a complete flight planning software suite, or may operate independently of the flight planning software on a mobile device, such as a laptop or tablet computer, or other computing device that can be moved around. In some examples, the emergency destination determination subsystem 310 provides the list of destinations to the pilot via the flight management system. In other examples, the pilot selects one of these suitable emergency destinations, and information about the aircraft, such as the current aircraft position, aircraft health, estimated arrival time, and requested priority upon arrival, is sent to the selected airport.

[0109] Fig. 9 A flight path 900 is depicted near high altitude terrain features with a safe gradient descent to multiple landing sites.

[0110] In this example, aircraft 904 is flying on flight path 900 through safe flight zone 624 (and outside unsafe flight zone 626) when unexpected event 916 occurs. Aircraft 904 then turns to its right (in the safe descent direction) and descends along gradient ramp 914 to the altitude threshold, as described above. Once aircraft 904 reaches the altitude threshold, aircraft 904 may only need to travel a limited distance within emergency descent area 932 before landing (e.g., as in Figure 8 ) as described in the emergency destination determination subsystem 310 of .

[0111] Here, the emergency descent area 932 is a radius taken from the position of the aircraft 904 at the altitude threshold, but in other examples, it can be a radius taken from any position on the flight path or gradient ramp. However, the range of the aircraft 904 is affected by wind conditions (such as wind speed and wind direction), and the shape of the emergency descent area 932 will change based on the range of the aircraft 904 and may not be an exact circle. For example, a northerly wind 928 causes a headwind for the aircraft 904 during the gradient ramp 914 and reduces the range of the emergency descent area 932 in the direction of the wind (such as in this example). Conversely, a southerly wind will increase the range of the emergency descent area 932 in the direction of the wind.

[0112] In this example, emergency destination area 932 includes suitable emergency destinations and unsuitable emergency destinations (e.g., suitable emergency destination 934 and unsuitable emergency destination 936). Suitable emergency destinations are locations where aircraft 904 can land safely, while unsuitable emergency destinations are locations where aircraft 904 cannot land safely. In one example, suitable emergency destinations are represented by Figure 8 Step 822 provides that the inappropriate emergency destination is from Figure 8 The remaining emergency destinations of step 816.

[0113] Example of a method for determining flight plans over or near high altitude terrain features

[0114] Fig.10 An example method 1000 for determining a flight plan for an aircraft from an origin to a destination is depicted.

[0115] Method 1000 begins at step 1002 where a region is determined that intersects an initial flight path and includes at least one terrain feature having an altitude greater than an altitude threshold.

[0116] Then, method 1000 proceeds to step 1004, wherein a flight zone within the region is determined based on the initial flight path and the altitude threshold line. In some embodiments, the altitude threshold line indicates the following portion of the corresponding region, that is, in the portion, along the safe descent direction of the region, all terrain is below the altitude threshold.

[0117] Method 1000 then proceeds to step 1006 where a segment of the initial flight path in the area that includes one or more terrain features having an altitude greater than an altitude threshold is determined.

[0118] Then, method 1000 proceeds to step 1008, where a plurality of gradient ramps from a plurality of locations along the flight segment and from an estimated cruising altitude to an altitude threshold are determined. In some embodiments, the gradient ramp is determined based on an estimated descent time from the estimated cruising altitude to the altitude threshold.

[0119] Method 1000 then proceeds to step 1010 where the segment of the initial flight path is moved in a safe descent direction if any of the plurality of gradient ramps would conflict with any of the one or more terrain features along the corresponding segment.

[0120] In some embodiments, the modified flight path for the area is between the initial flight path and an altitude threshold line within a flight zone of the corresponding area.

[0121] Some embodiments of method 1000 also include the following steps: determining whether any of the multiple gradient declines will conflict with any of the one or more terrain features along the corresponding flight segment based on one or more of the following items: wind direction and wind speed for multiple altitudes between the estimated cruising altitude and the altitude threshold; and the maximum operating speed over the ground of the aircraft for each of the multiple altitudes.

[0122] Some embodiments of method 1000 further include the step of moving the segment of the initial flight path in a safe descent direction if any of the plurality of gradient ramps would violate a minimum obstacle clearance threshold associated with any of the one or more terrain features along the segment.

[0123] Some embodiments of method 1000 further include providing the modified flight path to the aircraft.

[0124] Some embodiments of method 1000 further include the following steps: determining one or more emergency destinations based on the modified flight path and the safe descent direction of the corresponding area relative to the modified flight path. In some embodiments, the one or more emergency destinations are determined based on one or more of the following items: wind conditions at the one or more emergency destinations; visibility conditions at the one or more emergency destinations; weather conditions at the one or more emergency destinations; distances from the modified flight path to the one or more emergency destinations; or runway lengths at the one or more emergency destinations.

[0125] Some embodiments of method 1000 further include the steps of: receiving updated wind directions and updated wind speeds for the plurality of altitudes between the actual cruising altitude and the altitude threshold; and determining a maximum operating speed over the ground for the aircraft for each of the plurality of altitudes.

[0126] In some implementations of method 1000 , the estimated descent time is based on a maximum safe vertical speed for the aircraft.

[0127] In some embodiments of method 1000, the initial flight path is determined based on a great circle flight path between the origin and the destination.

[0128] In some implementations of method 1000, the altitude threshold is equal to or less than 10,000 ft. In some implementations, the altitude threshold specifies a minimum obstacle clearance.

[0129] Notably, method 1000 is merely illustrative of certain aspects of the present disclosure, and fewer and / or other aspects may be present in other methods consistent with the present disclosure.

[0130] Example Processing System

[0131] Fig.11 An example processing system 1100 of a system for planning a flight plan for an aircraft is depicted. In general, an apparatus of an exemplary implementation of the present disclosure may include, contain, or be implemented in one or more fixed or portable electronic devices. Examples of suitable electronic devices include: smartphones, tablet computers, laptop computers, desktop computers, workstation computers, server computers, etc. The apparatus may include one or more of a plurality of components, such as, for example, a processor 1102 (e.g., a processing circuit) connected to a memory 1104 (e.g., a storage device). In some examples, the apparatus 1100 implements the systems and methods described herein to perform operations as described above with reference to Figures 2A to 10 Enhanced flight plan as described.

[0132] Processor 1102 may be composed of one or more processors alone or in combination with one or more memories. A processor is typically any computer hardware capable of processing information (e.g., data, computer programs, and / or other suitable electronic information). A processor is composed of a collection of electronic circuits, some of which may be packaged as integrated circuits or multiple interconnected integrated circuits (integrated circuits are sometimes more commonly referred to as "chips"). A processor may be configured to execute a computer program, which may be stored on the processor or otherwise stored in a memory 1106 (of the same device or another device).

[0133] According to a specific implementation, processor 1102 can be many processors, multi-core processors or some other type of processor. In addition, the processor can be implemented using many heterogeneous processor systems, wherein the main processor is present on a single chip together with one or more auxiliary processors. As another illustrative example, the processing unit can be a symmetric multiprocessor system comprising multiple processors of the same type. In another example, the processor can be embodied as or otherwise include one or more application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc. Therefore, although the processor can execute a computer program to perform one or more functions, the processor of each example can perform one or more functions without the aid of a computer program. In either case, the processor can be appropriately programmed to perform functions or operations implemented according to the examples of the present disclosure.

[0134] Memory 1104 is generally any computer hardware capable of temporarily and / or permanently storing information such as, for example, data, computer programs (e.g., computer readable program code 1106), and / or other suitable information. Memory may include volatile and / or non-volatile memory and may be fixed or removable. Examples of suitable memory include random access memory (RAM), read-only memory (ROM), hard drive, flash memory, thumb drive, removable computer disk, optical disk, tape, or a combination thereof. Optical disks may include compact disk read-only memory (CD-ROM), compact disk rewritable memory (CD-R / W), DVD, etc. In different cases, memory may be referred to as computer-readable storage media. Computer-readable storage media are non-temporary devices capable of storing information and may be distinguished from computer-readable transmission media such as electronic transient signals capable of transporting information from one location to another. Computer-readable media described herein may generally refer to computer-readable storage media or computer-readable transmission media.

[0135] In addition to the memory 1104, the processor 1102 may be connected to one or more interfaces for displaying, sending and / or receiving information. These interfaces may include a communication interface 1108 (e.g., a communication unit) and / or one or more user interfaces. The communication interface may be configured to, for example, send information to other devices, networks, etc. and / or receive information from other devices, networks, etc. The communication interface may be configured to send and / or receive information via a physical (wired) and / or wireless communication link. Examples of suitable communication interfaces include: a network interface controller (NIC), a wireless NIC (WNIC), etc.

[0136] The user interface may include a display 1112 and / or at least one user input interface 1110 (e.g., an input / output unit). The display may be configured to present or otherwise display information to a user, and suitable examples of displays include: a liquid crystal display (LCD), a light emitting diode display (LED), a plasma display panel (PDP), etc. The user input interface may be wired or wireless, and may be configured to receive information from a user into the device, such as for processing, storage, and / or display. Suitable examples of user input interfaces include: a microphone, a keyboard or keypad, a joystick, a touch-sensitive surface (separate from or integrated into a touch screen), a biometric sensor, etc. The user interface may also include one or more interfaces for communicating with peripheral devices (such as a printer, a scanner, etc.). In some examples, the user interface includes a graphical user interface (GUI).

[0137] As shown above, program code instructions can be stored in a memory, and executed by a processor, and the program code instructions are thus programmed to realize the functions of the systems, subsystems, tools, and their corresponding parts described herein. As will be appreciated, any suitable program code instructions can be loaded onto a computer or other programmable device from a computer-readable storage medium to generate a specific machine so that the specific machine becomes the device for realizing the functions specified herein. These program code instructions can also be stored in a computer-readable storage medium, and these program code instructions can instruct a computer, a processor, or other programmable device to work in a particular manner, thereby generating a specific machine or a specific product. The instructions stored in a computer-readable storage medium can generate products, wherein the products become the devices for realizing the functions described herein. Program code instructions can be retrieved from a computer-readable storage medium, and the program code instructions can be loaded into a computer, a processor, or other programmable device, so that the computer, processor, or other programmable device is configured, thereby performing the operation to be performed on the computer, processor, or other programmable device or the operation to be performed by the computer, processor, or other programmable device.

[0138] The retrieval, loading, and execution of program code instructions may be performed sequentially, such that retrieval, loading, and execution are performed one instruction at a time. In some example implementations, retrieval, loading, and / or execution may be performed in parallel, such that multiple instructions are retrieved, loaded, and / or executed together. The execution of program code instructions may generate a computer-implemented process such that instructions executed by a computer, processor, or other programmable device provide operations for implementing the functions described herein.

[0139] The processor executes instructions or stores instructions in a computer-readable storage medium to support a combination of operations for performing specified functions. In this manner, the device 1100 may include a processor 1102 and a computer-readable storage medium or memory 1104 coupled to the processor 1102, wherein the processor 1102 is configured to execute a computer-readable program code 1106 stored in the memory 1104. It should also be understood that one or more functions and combinations of functions may be implemented by a dedicated hardware-based computer system and / or processor that performs the specified functions or a combination of dedicated hardware and program code instructions.

[0140] Sample Clauses

[0141] Clause 1: A method for determining a flight plan of an aircraft from a starting point to a destination, the method comprising the following steps: determining one or more areas that intersect an initial flight path and include at least one terrain feature, the at least one terrain feature having an altitude greater than an altitude threshold; for each corresponding area in the one or more areas, performing the following operations: determining a flight zone within the corresponding area based on the initial flight path and an altitude threshold line, wherein the altitude threshold line indicates a portion of the corresponding area in which all terrain is below the altitude threshold along a safe descent direction of the corresponding area; determining one or more segments of the initial flight path in the corresponding area, the one or more segments including a portion having an altitude greater than the altitude threshold. one or more terrain features; and determining a modified flight path for each of the one or more segments of the initial flight path in the corresponding area by: determining a plurality of gradient ramps from a plurality of locations along the corresponding segment and from the estimated cruising altitude to the altitude threshold based on an estimated descent time from the estimated cruising altitude to the altitude threshold; and moving the corresponding segment of the initial flight path along the safe descent direction if any of the plurality of gradient ramps would conflict with any of the one or more terrain features along the corresponding segment, wherein the modified flight path of the corresponding area is between the initial flight path and the altitude threshold line within the flight zone of the corresponding area.

[0142] Clause 2: The method according to Clause 1 further comprises the following steps: determining whether any of the multiple gradient declines will conflict with any of the one or more terrain features along the corresponding flight segment based on: wind direction and wind speed for multiple altitudes between the estimated cruising altitude and the altitude threshold; and the maximum operating speed of the aircraft over the ground for each of the multiple altitudes.

[0143] Clause 3. The method according to any one of clauses 1 to 2, further comprising the following steps: for each corresponding segment of the one or more segments of the initial flight path in the corresponding area, performing the following operation: if any of the multiple gradient declines will violate the minimum obstacle clearance threshold associated with any of the one or more terrain features along the corresponding segment, then moving the corresponding segment of the initial flight path along the safe descent direction.

[0144] Clause 4. The method of any one of clauses 1 to 3, wherein the estimated descent time is based on a maximum safe vertical speed of the aircraft.

[0145] Clause 5. A method according to any one of clauses 1 to 4, wherein the initial flight path is determined based on a great circle flight path between the starting point and the destination.

[0146] Clause 6. The method of any of clauses 1 to 5, wherein the altitude threshold is in the range of 8,000 feet to 10,000 feet.

[0147] Clause 7. The method according to any one of clauses 1 to 6, further comprising the step of providing the modified flight path to the aircraft.

[0148] Clause 8. The method according to any one of clauses 1 to 7, further comprising the following steps: for each corresponding area among the one or more areas, performing the following operations: determining one or more emergency destinations based on the modified flight path and the safe descent direction of the corresponding area relative to the modified flight path.

[0149] Clause 9. A method according to Clause 8, wherein the one or more emergency destinations are determined based on one or more of the following items: wind conditions at the one or more emergency destinations; visibility conditions at the one or more emergency destinations; weather conditions at the one or more emergency destinations; the distance from the modified flight path to the one or more emergency destinations; or the runway length of the one or more emergency destinations.

[0150] Clause 10. The method according to any one of clauses 1 to 9, further comprising the steps of: receiving updated wind directions and updated wind speeds for the multiple altitudes between the actual cruising altitude and the altitude threshold; and determining the maximum operating speed over the ground of the aircraft for each of the multiple altitudes.

[0151] Clause 11. A processing system, the processing system comprising: a memory, the memory comprising computer executable instructions; one or more processors, the one or more processors being configured to execute the computer executable instructions and causing the processing system to perform the following operations: determining one or more areas that intersect with an initial flight path and include at least one terrain feature, the at least one terrain feature having an altitude greater than an altitude threshold; for each corresponding area in the one or more areas, performing the following operations: determining a flight zone within the corresponding area based on the initial flight path and an altitude threshold line, wherein the altitude threshold line indicates a portion of the corresponding area in which all terrain is below the altitude threshold along a safe descent direction of the corresponding area; determining one or more flight zones of the initial flight path in the corresponding area; a segment, the one or more segments including one or more terrain features having an altitude greater than the altitude threshold; and determining a modified flight path for each of the one or more segments of the initial flight path in the corresponding area by: determining a plurality of gradient ramps from a plurality of locations along the corresponding segment and from the estimated cruising altitude to the altitude threshold based on an estimated descent time from the estimated cruising altitude to the altitude threshold; and moving the corresponding segment of the initial flight path in the safe descent direction if any of the plurality of gradient ramps will conflict with any of the one or more terrain features along the corresponding segment, wherein the modified flight path of the corresponding area is between the initial flight path and the altitude threshold line within the flight zone of the corresponding area.

[0152] Clause 12. A processing system according to clause 11, wherein the one or more processors are further configured to enable the processing system to: determine whether any of the multiple gradient declines will conflict with any of the one or more terrain features along the corresponding flight segment based on: wind direction and wind speed for multiple altitudes between the estimated cruising altitude and the altitude threshold; and the maximum operating speed of the aircraft over the ground for each of the multiple altitudes.

[0153] Clause 13. A processing system according to any of clauses 11 to 12, wherein the one or more processors are further configured to cause the processing system to perform the following operation for each corresponding segment of the one or more segments of the initial flight path in the corresponding area: if any of the multiple gradient declines will violate the minimum obstacle clearance threshold associated with any of the one or more terrain features along the corresponding segment, then move the corresponding segment of the initial flight path along the safe descent direction.

[0154] Clause 14. The processing system of any of clauses 11 to 13, wherein the estimated descent time is based on a maximum safe vertical speed of the aircraft.

[0155] Clause 15. A processing system according to any one of clauses 11 to 14, wherein the initial flight path is determined based on a great circle flight path between the starting point and the destination.

[0156] Clause 16. The processing system of any of Clauses 11 to 15, wherein the one or more processors are further configured to cause the processing system to: provide the modified flight path to the aircraft.

[0157] Clause 17. A processing system according to any of clauses 11 to 16, wherein the one or more processors are further configured to cause the processing system to perform the following operations for each corresponding area among the one or more areas: determine one or more emergency destinations based on the modified flight path and the safe descent direction of the corresponding area relative to the modified flight path.

[0158] Clause 18. A processing system according to Clause 17, wherein the one or more emergency destinations are determined based on one or more of the following items: wind conditions at the one or more emergency destinations; visibility conditions at the one or more emergency destinations; weather conditions at the one or more emergency destinations; the distance from the modified flight path to the one or more emergency destinations; or the runway length of the one or more emergency destinations.

[0159] Clause 19. A processing system according to any one of clauses 11 to 18, wherein the one or more processors are further configured to enable the processing system to: receive updated wind directions and updated wind speeds for the multiple altitudes between the actual cruising altitude and the altitude threshold; and determine the maximum operating speed over the ground of the aircraft for each of the multiple altitudes.

[0160] Clause 20. A non-transitory computer-readable medium comprising computer-executable instructions, which, when executed by a processing system, cause the processing system to perform a method for determining a flight plan of an aircraft from a starting point to a destination, the method comprising the following steps: determining one or more areas that intersect an initial flight path and include at least one terrain feature, wherein the at least one terrain feature has an altitude greater than an altitude threshold; for each corresponding area in the one or more areas, performing the following operations: determining a flight area within the corresponding area based on the initial flight path and an altitude threshold line, wherein the altitude threshold line indicates a portion of the corresponding area in which all terrain is below the altitude threshold along a safe descent direction of the corresponding area; determining one or more segments of the initial flight path in the corresponding area , the one or more flight segments include one or more terrain features having an altitude greater than the altitude threshold; and determining a modified flight path for each of the one or more flight segments of the initial flight path in the corresponding area by: determining a plurality of gradient ramps from a plurality of locations along the corresponding flight segment and from the estimated cruising altitude to the altitude threshold based on an estimated descent time from the estimated cruising altitude to the altitude threshold; and moving the corresponding flight segment of the initial flight path in the safe descent direction if any of the plurality of gradient ramps will conflict with any of the one or more terrain features along the corresponding flight segment, wherein the modified flight path of the corresponding area is between the initial flight path and the altitude threshold line within the flight zone of the corresponding area.

[0161] Additional matters

[0162] The description of various aspects of the present invention has been presented for the purpose of illustration, but is not intended to be exhaustive or limited to the disclosed aspects. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described aspects. The terminology used herein is selected to best illustrate the principles of the various aspects, practical applications or technical improvements over technologies found in the market, or to enable others of ordinary skill in the art to understand the various aspects disclosed herein.

[0163] While the foregoing is directed to various aspects of the present invention, other and further aspects of the invention may be envisaged without departing from the basic scope thereof and the scope of the invention is determined by the appended claims.

Claims

1. A method for determining a flight plan (302) of an aircraft (104, 604, 904) from an origin to a destination, the method comprising the steps of: determining one or more regions (106, 108, 108a, 208, 306b, 508, 708) that intersect the initial flight path (100a, 500a) and include at least one terrain feature (210), the at least one terrain feature (210) having an altitude (1002) greater than an altitude threshold (212, 712); For each corresponding area in the one or more areas (106, 108, 108a, 208, 306b, 508, 708), perform the following operations: determining a flight zone within the corresponding region based on the initial flight path (100a, 500a) and an altitude threshold line (124, 224, 408, 524, 624a), wherein the altitude threshold line (124, 224, 408, 524, 624a) indicates a portion of the corresponding region in which all terrain along a safe descent direction (218) of the corresponding region is below the altitude threshold (212, 712) (1004); determining one or more segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the corresponding area, the one or more segments (102a, 102b, 102c, 410, 502a) including one or more terrain features (210) having an altitude greater than the altitude threshold (212, 712) (1006); and Determining a modified flight path (500b, 600b) for each respective one of the one or more flight segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the respective region by: determining a plurality of gradient ramps (214, 714a, 714b, 714c, 914) (422, 1008) from a plurality of locations along the corresponding flight segment and from the estimated cruising altitude to the altitude threshold (211, 711) based on the distance traveled over the ground from the estimated cruising altitude to the altitude threshold (211, 711), wherein the maximum operating speed over the ground of the aircraft is calculated based on the maximum operating speed of the aircraft at the estimated cruising altitude, the wind direction and the wind speed, and the distance traveled over the ground is determined based on the maximum operating speed over the ground and the estimated descent time (412) from the estimated cruising altitude to the altitude threshold (211, 711); and moving the corresponding flight segment (428a) (1010) of the initial flight path (100a, 500a) in the safe descent direction (218) if any of the plurality of gradient declines (214, 714a, 714b, 714c, 914) would conflict with any of the one or more terrain features (210) along the corresponding flight segment, wherein the modified flight path (500b, 600b) of the corresponding area is between the initial flight path (100a, 500a) and the altitude threshold line (124, 224, 408, 524, 624a) within the flight zone of the corresponding area.

2. The method according to claim 1, further comprising the steps of: Determining whether any of the plurality of gradient ramps (214, 714a, 714b, 714c, 914) will conflict with any of the one or more terrain features (210) along the corresponding flight segment is based on: wind direction and wind speed (306e) for a plurality of altitudes between the estimated cruising altitude and the altitude threshold (211, 711); and A maximum operating speed over the ground of the aircraft for each of the plurality of altitudes (416).

3. The method according to claim 1 or 2, further comprising the following steps: For each corresponding segment of the one or more segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the corresponding area, perform the following operations: If any of the plurality of gradient ramps (214, 714a, 714b, 714c, 914) would violate a minimum obstacle clearance threshold (220, 306g, 720) associated with any of the one or more terrain features (210) along the corresponding flight segment, moving the corresponding flight segment (428a) along the safe descent direction (218).

4. The method according to claim 1 or 2, wherein: The estimated descent time (412) is based on a maximum safe vertical speed (306c) for the aircraft.

5. The method according to claim 1 or 2, wherein: The initial flight path (100a, 500a) is determined based on a great circle flight path (600a) between the starting point and the destination (306a).

6. The method according to claim 1 or 2, wherein: The altitude threshold (212, 712) is in the range of 8,000 feet to 10,000 feet.

7. The method according to claim 1 or 2, further comprising the following steps: The modified flight path (500b, 600b) is provided to the aircraft (104, 604, 904).

8. The method according to claim 1 or 2, further comprising the following steps: For each corresponding area in the one or more areas (106, 108, 108a, 208, 306b, 508, 708), perform the following operations: One or more emergency destinations (934, 936) are determined based on the modified flight path (500b, 600b) and the safe descent direction (218) of the corresponding area relative to the modified flight path (500b, 600b).

9. A processing system (1100), the processing system (1100) comprising: a memory (1104) comprising computer executable instructions (1106); One or more processors (1102), the one or more processors (1102) configured to execute the computer executable instructions (1106) and cause the processing system (1100) to perform the following operations: determining one or more regions (106, 108, 108a, 208, 306b, 508, 708) that intersect the initial flight path (100a, 500a) and include at least one terrain feature (210), the at least one terrain feature (210) having an altitude greater than an altitude threshold (212, 712); For each corresponding area in the one or more areas (106, 108, 108a, 208, 306b, 508, 708), perform the following operations: determining a flight zone within the corresponding region based on the initial flight path (100a, 500a) and an altitude threshold line (124, 224, 408, 524, 624a), wherein the altitude threshold line (124, 224, 408, 524, 624a) indicates a portion of the corresponding region in which all terrain along a safe descent direction (218) of the corresponding region is below the altitude threshold (212, 712); determining one or more segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the corresponding area, the one or more segments (102a, 102b, 102c, 410, 502a) including one or more terrain features (210) having an altitude greater than the altitude threshold (212, 712); and Determining a modified flight path (500b, 600b) for each respective one of the one or more flight segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the respective region by: determining a plurality of gradient descents (214, 714a, 714b, 714c, 914) (422) from a plurality of locations along the corresponding flight segment and from the estimated cruising altitude to the altitude threshold (211, 711) based on the distance traveled over the ground from the estimated cruising altitude to the altitude threshold (211, 711), wherein the maximum operating speed over the ground of the aircraft is calculated based on the maximum operating speed of the aircraft at the estimated cruising altitude, the wind direction and the wind speed, and the distance traveled over the ground is determined based on the maximum operating speed over the ground and an estimated descent time (412) from the estimated cruising altitude to the altitude threshold (211, 711); and moving the corresponding flight segment (428a) of the initial flight path (100a, 500a) in the safe descent direction (218) if any of the plurality of gradient declines (214, 714a, 714b, 714c, 914) would conflict with any of the one or more terrain features (210) along the corresponding flight segment, wherein the modified flight path (500b, 600b) of the corresponding area is between the initial flight path (100a, 500a) and the altitude threshold line (124, 224, 408, 524, 624a) within the flight zone of the corresponding area.

10. A non-transitory computer readable medium comprising computer executable instructions (1106) which, when executed by a processing system (1100), cause the processing system (1100) to perform a method of determining a flight plan (302) for an aircraft (104, 604, 904) from an origin to a destination, the method comprising the steps of: determining one or more regions (106, 108, 108a, 208, 306b, 508, 708) that intersect the initial flight path (100a, 500a) and include at least one terrain feature (210), the at least one terrain feature (210) having an altitude greater than an altitude threshold (212, 712); For each corresponding area in the one or more areas (106, 108, 108a, 208, 306b, 508, 708), perform the following operations: determining a flight zone within the corresponding region based on the initial flight path (100a, 500a) and an altitude threshold line (124, 224, 408, 524, 624a), wherein the altitude threshold line (124, 224, 408, 524, 624a) indicates a portion of the corresponding region in which all terrain along a safe descent direction (218) of the corresponding region is below the altitude threshold (212, 712); determining one or more segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the corresponding area, the one or more segments (102a, 102b, 102c, 410, 502a) including one or more terrain features (210) having an altitude greater than the altitude threshold (212, 712); and Determining a modified flight path (500b, 600b) for each respective one of the one or more flight segments (102a, 102b, 102c, 410, 502a) of the initial flight path (100a, 500a) in the respective region by: determining a plurality of gradient descents (214, 714a, 714b, 714c, 914) (422) from a plurality of locations along the corresponding flight segment and from the estimated cruising altitude to the altitude threshold (211, 711) based on the distance traveled over the ground from the estimated cruising altitude to the altitude threshold (211, 711), wherein the maximum operating speed over the ground of the aircraft is calculated based on the maximum operating speed of the aircraft at the estimated cruising altitude, the wind direction and the wind speed, and the distance traveled over the ground is determined based on the maximum operating speed over the ground and an estimated descent time (412) from the estimated cruising altitude to the altitude threshold (211, 711); and moving the corresponding flight segment (428a) of the initial flight path (100a, 500a) in the safe descent direction (218) if any of the plurality of gradient declines (214, 714a, 714b, 714c, 914) would conflict with any of the one or more terrain features (210) along the corresponding flight segment, wherein the modified flight path (500b, 600b) of the corresponding area is between the initial flight path (100a, 500a) and the altitude threshold line (124, 224, 408, 524, 624a) within the flight zone of the corresponding area.

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