Aircraft re-flight climbing gradient determination method based on flight data

Abstract

The invention belongs to the field of aviation safety and flight data processing, particularly relates to a flight data-based aircraft re-flight climbing gradient determination method, and aims to solve the problem that the existing aircraft re-flight climbing gradient is inaccurate. The method comprises the following steps: based on flight data of a target aircraft, identifying a re-flight action starting moment and a re-flight performance reconstruction moment; based on the flight data, non-standard atmospheric environment factors and local geographical environment factors influencing the geometric height of the aircraft are corrected, the corrected geometric height of the target aircraft is obtained, and a corrected flight track is reconstructed in combination with the real-time horizontal position of the target aircraft; and according to the re-flight motion starting moment, the re-flight performance reconstruction moment and the corrected flight path, determining a re-flight net climbing gradient of the target aircraft in a re-flight initial stage formed from the re-flight motion starting moment to the re-flight performance reconstruction moment. According to the method, the re-flight net climbing gradient containing the initial height loss can be quantified, and the actual re-flight performance of the target aircraft is truly restored.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aviation safety and flight data processing, and particularly relates to a method for determining a climb gradient of a repositioning flight of an aircraft based on flight data. BACKGROUND

[0002] The repositioning flight of an aircraft is a key maneuvering stage in the instrument approach and landing process, which refers to the process of interrupting landing and climbing to a specified height due to reasons such as weather conditions, runway intrusion, instruction requirements, or unstable approach state. The repositioning flight climb gradient is a key performance indicator for ensuring the safety of the aircraft in crossing ground obstacles, and reflects the ability of the aircraft to climb over obstacles. The instrument approach procedure is usually designed based on a minimum climb gradient of 2.5% to provide sufficient obstacle clearance.

[0003] The current evaluation of repositioning flight performance mainly relies on the theoretical performance data provided by the aircraft manufacturer during the type certification stage, which is based on standard atmospheric conditions and ideal operation models. However, in real flight operations, this evaluation method based on theoretical models has significant deviations from the actual situation, leading to potential risks to flight safety. For example, the theoretical evaluation takes the fixed instrument approach procedure repositioning point (MAPt) as the starting point, while the actual repositioning decision point is dynamic and variable (earlier or later than MAPt), resulting in a serious distortion of obstacle analysis and the inability to identify high-risk scenarios such as low-altitude repositioning. For example, the initial height loss during repositioning is not considered, and the assumption of atmospheric environment is too idealistic. Therefore, the existing technology relies on static theoretical models and cannot conduct dynamic closed-loop evaluation in combination with real flight data, environmental parameters, and actual operations. SUMMARY

[0004] To solve the above-mentioned problems in the prior art, i.e., the inaccuracy of the repositioning flight climb gradient of the existing aircraft, one embodiment of the present application provides a method for determining the repositioning flight climb gradient of an aircraft based on flight data, comprising:

[0005] Based on the flight data of the target aircraft, the repositioning action start time and the repositioning performance reconstruction time at which the stable climb ability is re-established are identified.

[0006] Based on the flight data, the non-standard atmospheric environmental factors and local geographical environmental factors that affect the geometric height of the aircraft are corrected to obtain the corrected geometric height of the target aircraft, and the corrected flight path is reconstructed in combination with the real-time horizontal position of the target aircraft.

[0007] According to the repositioning action start time, the repositioning performance reconstruction time, and the corrected flight path, the repositioning net climb gradient of the target aircraft in the initial stage of repositioning flight from the repositioning action start time to the repositioning performance reconstruction time is determined.

[0008] As a preferred embodiment, the identification step of the repositioning action start time comprises:

[0009] acquire a plurality of flight parameters reflecting the state of the aircraft and the control input, wherein the flight parameters at least include a thrust lever angle, an autopilot mode, and an aircraft pitch angle;

[0010] determine a current time as a go-around action start time when the flight parameters simultaneously satisfy preset go-around action trigger conditions, wherein the go-around action trigger conditions include that the thrust lever angle increases and exceeds a go-around thrust threshold within a preset duration, the autopilot mode is switched to a go-around mode, and the aircraft pitch angle increases and exceeds a nose-up threshold within a preset duration.

[0011] As a preferred embodiment, the identification step of the go-around performance reconstruction time comprises:

[0012] determine a time when the target aircraft first simultaneously satisfies predefined performance establishment conditions as the go-around performance reconstruction time after the go-around action start time; wherein the performance establishment conditions include that the geometric height of the target aircraft exceeds the height at the go-around action start time, the flight speed reaches a preset reference speed, the vertical speed remains positive within a preset duration, and the pitch angle reaches a preset climb attitude angle.

[0013] As a preferred embodiment, the corrected aircraft geometric height of the target aircraft is acquired, comprising:

[0014] inversion of the atmospheric static pressure based on the barometric altitude recorded by the onboard system;

[0015] acquisition of the air effective gas constant affected by water vapor based on the measured atmospheric temperature and environmental humidity information;

[0016] determination of the local value of the gravitational acceleration based on the geographical latitude and the altitude of the target aircraft;

[0017] recursion of the corrected aircraft geometric height reflecting the true physical height by solving the fluid statics balance equation based on the atmospheric static pressure, the effective gas constant, the local value of the gravitational acceleration, and the measured static temperature.

[0018] As a preferred embodiment, the corrected aircraft geometric height of the target aircraft is acquired, further comprising:

[0019] in the case of low-altitude flight of the target aircraft, the true height of the aircraft relative to the ground measured by the radio altimeter is taken as the corrected aircraft geometric height of the target aircraft.

[0020] As a preferred embodiment, the corrected flight path is reconstructed in combination with the real-time horizontal position of the target aircraft, comprising:

[0021] In the case that the signal quality of the global positioning system meets the preset reliability standard, the position data provided by the global positioning system is used as the real-time horizontal position of the target aircraft;

[0022] In the case that the signal quality of the global positioning system does not meet the preset reliability standard, the position data calculated by the inertial navigation system is used as the real-time horizontal position of the target aircraft.

[0023] As a preferred embodiment, the step of determining the net climb gradient of the go-around in the initial phase of the go-around includes:

[0024] At any time in the initial phase of the go-around, the height of the obstacle corresponding to the real-time horizontal position of the target aircraft is obtained;

[0025] The difference between the corrected geometric height of the aircraft at any time and the height of the obstacle is obtained as the net vertical margin of the target aircraft at any time;

[0026] The ratio of the net vertical margin and the horizontal forward distance is calculated as the instantaneous net climb gradient at any time, wherein the horizontal forward distance is the horizontal distance flown by the target aircraft since the starting time of the go-around action;

[0027] The minimum value of all the instantaneous net climb gradients in the initial phase of the go-around is determined as the net climb gradient of the go-around.

[0028] As a preferred embodiment, the method further includes:

[0029] The net climb gradient of the go-around is compared with the minimum climb gradient required by the instrument procedure;

[0030] If the net climb gradient of the go-around is lower than the minimum climb gradient, a go-around risk event alarm is triggered.

[0031] As a preferred embodiment, the method further includes:

[0032] The minimum true ground clearance height in the initial phase of the go-around is compared with the minimum ground clearance height specified by the flight procedure to generate an initial phase obstacle clearance margin ratio;

[0033] In the go-around climb phase constituted by the time after the go-around performance reconstruction time to the end point of the go-around procedure, the minimum net climb gradient is determined, and the minimum net climb gradient is compared with the minimum climb gradient required by the instrument procedure to generate a climb phase obstacle clearance margin ratio;

[0034] Based on the initial phase obstacle clearance margin ratio and the climb phase obstacle clearance margin ratio, the cause of the go-around risk is determined to be a control factor risk or an aircraft performance deficiency risk.

[0035] As a preferred embodiment, the method further includes:

[0036] The go-around action starting time, go-around performance reconstruction time, initial stage obstacle clearance margin ratio, and climb stage obstacle clearance margin ratio of each go-around event are encapsulated into a structured go-around event archive and archived;

[0037] The historical archived multiple go-around event archives are aggregated and analyzed to calculate safety performance indicators in different dimensions.

[0038] Compared with the prior art, the technical scheme provided by the embodiment of the application has at least one of the following beneficial effects:

[0039] The application can quantize the go-around net climb gradient including initial height loss by accurately identifying the dynamic go-around starting time, scientifically dividing the go-around stage, and reconstructing the corrected flight path considering the influence of non-standard atmosphere, and truly restores the actual go-around performance of the target aircraft.

[0040] The application can objectively evaluate the go-around performance of the target aircraft under different operating conditions by fusing multiple source flight parameters combined with atmospheric environment correction, realize high-precision and forward-looking monitoring of the go-around performance of the target aircraft under different operating conditions, and improve the overall flight safety level. It makes up for the shortcomings of the theoretical model, and can be widely applied to flight quality monitoring of airlines, evaluation of go-around operation of pilots, and aviation safety management system, providing a data-driven safety management tool for airlines and regulatory agencies, so as to more effectively identify and control the operating risks in the go-around stage. BRIEF DESCRIPTION OF DRAWINGS

[0041] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0042] Figure 1 is a flowchart of a flight data-based aircraft go-around climb gradient determination method provided by an embodiment of the application;

[0043] Figure 2 is a system block diagram of a flight data-based aircraft go-around climb gradient determination system provided by an embodiment of the application;

[0044] Figure 3 is a structural schematic diagram of a computer system of a server for implementing the method, system and electronic device embodiments of the application. DETAILED DESCRIPTION

[0045] The application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings.

[0046] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0047] The present application provides a method for determining the climb gradient of a reflight of an aircraft based on flight data. Based on the flight data of the target aircraft, the starting time of the reflight action and the re-establishment time of the stable climb capability of the reflight performance are identified. Based on the flight data, the non-standard atmospheric environmental factors and local geographical environmental factors affecting the geometric height of the aircraft are corrected to obtain the corrected geometric height of the target aircraft, and the corrected flight path is reconstructed in combination with the real-time horizontal position of the target aircraft. According to the starting time of the reflight action, the re-establishment time of the reflight performance and the corrected flight path, the net climb gradient of the target aircraft in the initial stage of the reflight from the starting time of the reflight action to the re-establishment time of the reflight performance is determined. The present application can quantize the net climb gradient of the reflight containing the initial height loss by accurately identifying the starting time of the dynamic reflight, scientifically dividing the reflight stage and reconstructing the corrected flight path considering the influence of non-standard atmosphere, and truly restores the actual reflight performance of the target aircraft.

[0048] In order to more clearly describe the method for determining the climb gradient of a reflight of an aircraft based on flight data, the following will be described in combination with Figure 1 The steps in the embodiments of the present application will be described in detail.

[0049] The method for determining the climb gradient of a reflight of an aircraft based on flight data in the first embodiment of the present application comprises steps S10-S30, and the steps are described in detail as follows:

[0050] Step S10, based on the flight data of the target aircraft, the starting time of the reflight action and the re-establishment time of the stable climb capability of the reflight performance are identified.

[0051] Optionally, the flight data of the target aircraft is first obtained. These data are usually obtained from the on-board quick access recorder (QAR) or digital access recorder (DAR), which records detailed flight parameter sequences at a high frequency (for example, once per second or higher). Among them, the flight data is various quantized state information of the target aircraft and its running environment generated in the flight process, for example, including aircraft speed, height, state, flight tube computer mode, atmospheric environment, engine and other multi-dimensional parameters.

[0052] Before using these flight data, the original data usually needs to be pre-processed, including data decoding, time alignment, data cleaning (such as wild point elimination and missing value interpolation) and smoothing filtering of key parameters, to ensure the high quality and reliability of the data used for subsequent analysis.

[0053] It should be noted that the current missed approach performance assessment assumes that the missed approach starts at the missed approach point (MAPt) preset in the instrument approach procedure, which generally corresponds to the decision height or minimum descent altitude of 200 to 500 feet from the runway. However, in actual operation, the missed approach decision made by the pilot due to weather, unstable approach, runway intrusion and other factors has significant dynamics, and the missed approach action is often much earlier or later than MAPt, including missed approach below 50 feet or even after landing. Such deviation leads to serious distortion of the obstacle analysis based on the fixed theoretical starting point: missed approach earlier than MAPt may occur outside the program obstacle protection zone; and missed approach later than MAPt, especially at low altitude, has actual climb performance much lower than the manual value due to insufficient initial energy and significant height loss, but the traditional method cannot identify such high-risk scenarios, nor can it accurately reflect the climb gradient.

[0054] Therefore, further, based on the flight data of the target aircraft, the starting time of the missed approach action reflecting the real operation intention of the pilot is dynamically identified, and the missed approach performance reconstruction time reflecting the ability of the target aircraft to re-establish stable climb is also dynamically identified. To overcome the analysis distortion caused by the prior art relying on the fixed instrument procedure missed approach point (MAPt).

[0055] Specifically, a plurality of flight parameters reflecting the state of the aircraft and the input of the control are obtained, and when the flight parameters simultaneously satisfy a preset missed approach action triggering condition, the current time is determined as the starting time of the missed approach action.

[0056] Among them, the flight parameters at least include the thrust lever angle, the flight computer mode and the aircraft pitch angle, and the missed approach action triggering condition includes that the thrust lever angle increases and exceeds the missed approach thrust threshold within a preset duration, the flight computer mode is converted to the missed approach mode, and the aircraft pitch angle increases and exceeds the nose-up threshold within a preset duration.

[0057] In order to accurately capture the missed approach intention of the pilot, the identification step of the starting time of the missed approach action includes jointly determining a plurality of flight parameters reflecting the state of the aircraft and the input of the control. When these flight parameters simultaneously satisfy a set of preset missed approach action triggering conditions, the current time is determined as the starting time of the missed approach action. In this embodiment, these flight parameters at least include the thrust lever angle (TLA), the flight computer (FMA) mode and the aircraft pitch angle (AOF) ). The takeoff reject action trigger condition can be specifically set as: a trend of continuously increasing of the thrust lever angle is observed within a preset duration (e.g., 3 seconds), and the value of the thrust lever angle exceeds a takeoff reject thrust threshold (e.g., for a certain example aircraft model, the threshold can be set to 33 degrees, representing that the thrust lever is pushed into the TOGA position); at the same time, the flight tube computer mode is correspondingly converted to the takeoff reject mode (e.g., the FMA displays “MANTOGA” or “TOGA”); and, the aircraft pitch angle also presents a trend of continuously increasing within the same duration, and the value of the aircraft pitch angle exceeds a nose-up threshold (e.g., 10 degrees). Through this multi-parameter joint determination manner, abnormal fluctuations caused by air flow turbulence or temporary operation can be effectively excluded, so as to accurately identify the real starting point of the takeoff reject operation performed by the pilot.

[0058] In order to exclude temporary abnormal fluctuations and improve detection accuracy, the preset duration is set as a judgment standard in the embodiments of the present application, and after each parameter abnormality exceeds the preset duration, it is confirmed that the corresponding takeoff reject action trigger condition is met.

[0059] By jointly analyzing multiple real flight parameters such as the thrust lever angle, the flight tube computer mode and the pitch angle, the real starting time of the takeoff reject decision made by the pilot can be dynamically identified, rather than relying on the theoretical takeoff reject point. This enables the present application to accurately capture and evaluate non-programmed takeoff rejects occurring at any height and any position, especially low-height, late takeoff rejects and other high-risk scenarios, and fundamentally solves the evaluation distortion problem caused by rigid definition of the starting point in the prior art.

[0060] After the takeoff reject action starting time is determined, the state of the target aircraft is continuously monitored to identify the takeoff reject performance recovery time. The takeoff reject performance recovery time marks that the target aircraft has recovered to a safe state with stable climbing ability from the initial energy loss and height drop transition phase.

[0061] Specifically, after the takeoff reject action starting time, the time when the target aircraft first simultaneously meets the predefined performance establishment condition is determined as the takeoff reject performance recovery time.

[0062] The performance establishment condition includes that the geometric height of the target aircraft exceeds the height at the takeoff reject action starting time, the flight speed reaches a preset reference speed, the vertical speed remains positive within a preset duration, and the pitch angle reaches a preset climbing attitude angle.

[0063] The moment when the target aircraft first meets a set of predefined performance establishment conditions after the moment of the start of the go-around maneuver is determined as the moment of the performance re-establishment of the go-around. These performance establishment conditions are intended to ensure that the target aircraft has recovered a safe climb energy state, and can specifically include: the geometric height of the target aircraft is recovered to and exceeds its height at the moment of the start of the go-around maneuver, which indicates that the height loss stage due to descent inertia has ended; the flight speed of the target aircraft reaches or exceeds a preset reference speed; the vertical speed of the target aircraft is stably maintained as a positive value for a preset duration, ensuring that the target aircraft has established a sustained climb rate; and the pitch angle of the target aircraft reaches or exceeds a preset climb attitude angle, indicating that the target aircraft is in a stable climb attitude.

[0064] As an example, the moment of the performance re-establishment of the go-around may be determined by the following formula:

[0065] ;

[0066] wherein t represents a moment, represents the moment of the start of the go-around maneuver, represents the geometric height of the target aircraft at the moment t, represents the geometric height of the target aircraft at the moment of the start of the go-around maneuver, represents the flight speed of the target aircraft at the moment t, represents the reference speed during the approach, represents the target go-around speed specified in a special procedure, represents the vertical speed of the target aircraft at the moment t, represents a preset duration of 3 seconds, represents the pitch angle of the target aircraft at the moment t.

[0067] In the embodiments of the present application, the flight speed refers to the aircraft surface speed of the target aircraft, the preset reference speed refers to the reference speed during the approach and the target go-around speed specified in some special procedures , and the preset climb attitude angle is .

[0068] Further, after the moment of the start of the go-around maneuver and the moment of the performance re-establishment of the go-around are determined, an initial go-around stage can be obtained, which is an energy re-establishment stage of the target aircraft in the go-around procedure, includes thrust response, attitude adjustment, height loss and speed re-establishment, and is the weakest stage of obstacle crossing capability.

[0069] In some embodiments, the present application can also process historical flight data, and determine a go-around procedure endpoint The determination is made, for example, the moment when the target aircraft flies over the published missed approach termination point in the approach chart is determined as the missed approach procedure end point, or the moment when the target aircraft reaches the specified missed approach termination altitude of the procedure is determined as the missed approach procedure end point. As an example, the missed approach termination altitude is 3000 feet, and in the absence of explicit procedures, the target aircraft's geometric altitude ≥ 3000 feet and the aircraft's track is stable into the en route phase, the current time is determined as the missed approach procedure end point.

[0070] Further, the missed approach performance reconstruction time and the missed approach procedure end point constitute the missed approach climb phase , which has established the required speed, climb rate, etc. of the missed approach, and enters the obstacle protection area of the procedure design.

[0071] By identifying the missed approach action start time reflecting the pilot's true operation intention, and the missed approach performance reconstruction time representing the target aircraft's ability to re-establish stable climb, the missed approach phase is classified, the idealized assumption of "missed approach is climb" is abandoned, and the true flight state is used as the basis to provide a time sequence reference and physical boundary for subsequent high-precision calculation of net climb gradient, evaluation of obstacle clearance margin and identification of operation risk, significantly improving the objectivity and conservatism of missed approach performance evaluation.

[0072] Step S20, based on the flight data, the non-standard atmospheric environmental factors and local geographical environmental factors affecting the aircraft geometric altitude are corrected to obtain the corrected aircraft geometric altitude of the target aircraft, and the corrected flight track is reconstructed in combination with the real-time horizontal position of the target aircraft.

[0073] It should be noted that civil aircraft uses barometric altitude instead of true altitude, and the theoretical calculation of barometric altitude is based on the International Standard Atmosphere (ISA) model, i.e. temperature, pressure and density change with height in a fixed pattern. However, the actual atmospheric environment is complex and variable, especially the non-standard atmospheric phenomena such as temperature inversion, wind shear and high humidity often occurring in low altitude areas, which will significantly affect the engine thrust and aircraft aerodynamic performance, resulting in actual climb capability lower than theoretical expectation.

[0074] In the embodiments of the present application, the process of obtaining the corrected aircraft geometric altitude is a deep correction to the traditional method of calculating barometric altitude based on the standard atmospheric model.

[0075] Specifically, the atmospheric static pressure is obtained based on the air pressure height recorded by the airborne system; the effective air gas constant affected by the water vapor is obtained based on the measured atmospheric temperature and environmental humidity information; the local gravity acceleration value is determined based on the geographical latitude and the altitude of the target aircraft; and the corrected aircraft geometric height reflecting the true physical height is recursively obtained by solving the fluid statics balance equation, based on the atmospheric static pressure, the effective gas constant, the local gravity acceleration value and the measured static temperature.

[0076] As an example, based on the corrected sea level pressure (QNH) or field pressure (QFE) announced by the airport, the static pressure at the position of the target aircraft is obtained by using the air pressure height recorded by the airborne static pressure system . :

[0077] ;

[0078] wherein, represents the sea level standard atmospheric pressure defined in the international standard atmosphere, L represents the temperature reduction rate (the rate at which the temperature decreases with the increase of the height in the troposphere), represents the sea level standard temperature, g represents the standard gravity acceleration, M represents the molar mass of dry air, and R represents the universal gas constant.

[0079] It should be noted that the parameters in the above formula are all from the ISA standard, and the specific values are: , , , , , .

[0080] In order to more accurately reflect the true air density, the influence of environmental humidity needs to be considered. Specifically, based on the measured atmospheric temperature obtained from the flight data and the environmental humidity information (such as monthly average relative humidity) obtained from the airport channel (such as AIP), the water vapor partial pressure is calculated, and the dry air gas constant is corrected based on this to obtain the effective air gas constant affected by the water vapor.

[0081] As an example, the effective air gas constant can be obtained by the following formula :

[0082] ;

[0083] ;

[0084] wherein, represents the specific gas constant of dry air, where RH is the monthly average relative humidity.

[0085] It is noted that the specific gas constant of dry air is the value obtained by dividing the universal gas constant by the molar mass of dry air, the specific gas constant of water vapor is the value obtained by dividing the universal gas constant by the molar mass of water, .

[0086] In addition, since the gravitational acceleration varies with latitude and altitude, this step also takes into account the geographical latitude and the altitude at which the target aircraft is located, and uses an accurate gravity model (e.g. GRS80 ellipsoid model) to determine the local gravitational acceleration value.

[0087] As an example, the local gravitational acceleration can be determined by the following formula:

[0088] .

[0089] Finally, the calculated atmospheric static pressure, effective gas constant, local gravitational acceleration, and measured static temperature are substituted into the hydrostatic equilibrium equation, and through discrete integration, the corrected aircraft geometric height reflecting the true physical height of the target aircraft is recursively calculated from a reference point at a known altitude (e.g. runway entrance).

[0090] As an example, the corrected aircraft geometric height can be determined by the following continuous form of geometric height integral formula:

[0091] ;

[0092] where denotes the corrected aircraft geometric height of the target aircraft at time t, denotes the geometric height of the reference point, denotes the reference static pressure at denotes the static pressure at the location of the target aircraft at time t, denotes the static pressure at the location of the target aircraft at time t, denotes the variable in the integration process, and denotes any intermediate pressure value between and , used to describe the path of continuous change of air pressure with altitude.

[0093] Since the flight data is a discrete sampling sequence, in actual calculation, piecewise constant assumption is adopted, and between adjacent sampling points and , it is assumed that , T, g, etc. remain unchanged, and the integral formula is simplified as follows: The numerical value at the time point t The item is analyzed and integrated, thereby obtaining a discrete recursive formula:

[0094] ;

[0095] wherein, represents the geometric height of the aircraft at the time point t, represents the geometric height of the aircraft at the time point t, represents the effective gas constant at the time point t, represents the measured atmospheric temperature at the time point t, represents the gravitational acceleration at the time point t, represents the static pressure at the time point t, represents the static pressure at the time point t.

[0096] For multiple sampling points, the discrete recursive formula is used in time sequence to calculate the true geometric height of the target aircraft at each sampling point on the entire flight path.

[0097] Further, in order to improve the vertical flight path accuracy in the near-ground critical flight stage, the step of obtaining the corrected aircraft geometric height can further include correction in the case of near-ground low-altitude flight.

[0098] Specifically, in the case of near-ground low-altitude flight of the target aircraft, the true height of the aircraft relative to the ground measured by the radio altimeter is taken as the corrected aircraft geometric height of the target aircraft.

[0099] In the case of near-ground low-altitude flight of the target aircraft, such as when the radio altimeter (RA) measures a height below a preset height threshold, the determination method of the vertical position is switched to take the true height of the aircraft relative to the ground measured by the radio altimeter as the corrected aircraft geometric height of the target aircraft at the time point.

[0100] The preset height threshold can be 50 feet, that is, in the case of radio altitude below 50 feet, the height measured by the radio altimeter plus the elevation of the runway entrance is taken as the aircraft geometric height of the target aircraft relative to the ground.

[0101] Under near-ground low-altitude flight, by switching the aircraft geometric height to the radio altitude, the static pressure error of the barometric altitude system that can exist near the ground can be effectively avoided, and the authenticity of the low-altitude vertical reference is ensured.

[0102] By fusing the measured temperature, humidity, local gravitational acceleration and other non-standard atmospheric parameters, and solving the fluid statics equation to reconstruct the flight path of the aircraft, the error caused by the traditional method relying on the international standard atmosphere (ISA) model is overcome. The application can truly reflect the actual spatial position and performance of the aircraft in harsh environments such as high temperature, high humidity, high altitude, etc., especially by seamlessly switching to radio altitude in the near-ground stage, ensuring the height accuracy of the vertical path, and providing a reliable data basis for subsequent net climb gradient calculation.

[0103] While reconstructing the vertical path, the accurate real-time horizontal position of the target aircraft also needs to be determined. In this embodiment, the global positioning system (GPS) and the inertial navigation system (INS) are combined to determine the real-time horizontal position of the target aircraft.

[0104] Specifically, in the case that the signal quality of the global positioning system meets the preset reliability standard, the position data provided by the global positioning system is used as the real-time horizontal position of the target aircraft; in the case that the signal quality of the global positioning system does not meet the preset reliability standard, the position data calculated by the inertial navigation system is used as the real-time horizontal position of the target aircraft.

[0105] The preset reliability standard can be that the GPS horizontal position error metric parameter (Horizontal Figure of Merit, HFOM) is not greater than 1 nautical mile and the position change rate is within a reasonable range (for example, not more than 10 km / s). In the case that the GPS meets the preset reliability standard, the latitude and longitude position data provided by the GPS is used as the real-time horizontal position of the target aircraft. Otherwise, switch to the position data calculated by the inertial navigation system (INS) according to the acceleration and angular velocity recorded by itself, also expressed in latitude and longitude, as the real-time horizontal position of the target aircraft.

[0106] Through the fusion strategy of GPS and INS, the jump or loss of position data can be effectively suppressed, and the horizontal path and the subsequent digital terrain or obstacle database used for obstacle analysis can be accurately aligned.

[0107] After obtaining the above data, a four-dimensional data set consisting of time stamp, longitude, latitude and corrected aircraft geometric height is formed as the corrected flight path of the target aircraft, as the real physical motion trajectory of the target aircraft in three-dimensional space, overcoming the geometric height distortion problem caused by the traditional method relying on the international standard atmosphere (ISA) model and the constant gravity assumption, especially for the reflight scene in non-standard atmospheric environment such as high altitude, high temperature and high humidity.

[0108] In the embodiments of the present application, the static pressure is inversely calculated based on the air pressure, seamlessly switched to the radio height below 50 feet, and the authenticity of the low-altitude vertical reference is ensured; the effective gas constant with humidity correction and the gravity model based on GRS80 ellipsoid are introduced, and the limitations of the international standard atmosphere assumption are broken through; the geometric height under the non-standard atmospheric conditions is accurately calculated through the continuous integration of the fluid statics equation and its discretization; and the GPS and INS are fused to effectively suppress the position jump and ensure the spatial alignment accuracy of the horizontal flight path and the terrain or elevation database. The modified flight path generated thereby can truly reflect the spatial motion state of the target aircraft in the reflight process, and fundamentally solves the three core defects of "height distortion, position drift, and environment disconnection" in the traditional reflight performance evaluation, and also provides a unified reference that is physically consistent, spatially aligned, and environmentally reliable for subsequent obstacle analysis, climb gradient calculation, and risk identification.

[0109] In step S30, the reflight net climb gradient of the target aircraft in the reflight initial stage constituted by the reflight action starting time, the reflight performance reconstruction time, and the modified flight path is determined.

[0110] Optionally, the reflight climb gradient, i.e., the ratio of the height increment of the target aircraft in the vertical direction to the horizontal forward distance, can be determined according to the modified flight path to determine the geometric height and the real-time horizontal position of the aircraft at any time during the reflight process, and then determine the corresponding height increment to obtain the reflight climb gradient.

[0111] Specifically, at any time in the reflight initial stage, the obstacle elevation corresponding to the real-time horizontal position of the target aircraft is obtained; the difference between the modified geometric height of the aircraft at any time and the obstacle elevation is obtained as the net vertical margin of the target aircraft at any time; the ratio of the net vertical margin to the horizontal forward distance is calculated as the instantaneous net climb gradient at any time, wherein the horizontal forward distance is the horizontal distance flown by the target aircraft since the reflight action starting time; the minimum value of all the instantaneous net climb gradients in the reflight initial stage is determined as the reflight net climb gradient.

[0112] In the embodiments of the present application, at any time in the reflight initial stage, the real-time horizontal position of the target aircraft at that time is used to query the preloaded digital terrain model (DTM) or obstacle database to obtain the highest obstacle elevation corresponding to the horizontal position directly below. The difference between the modified geometric height of the aircraft at that time and the highest obstacle elevation is obtained as the net vertical margin of the target aircraft at that time, i.e., the height increment of the target aircraft in the vertical direction, and the ratio between the net vertical margin and the horizontal forward distance is calculated to obtain the instantaneous net climb gradient at that time.

[0113] As an example, the instantaneous net climb gradient at any time t can be determined by the following equation :

[0114] ;

[0115] wherein, represents the corrected aircraft geometric height of the target aircraft at time t, represents the highest obstacle elevation at time t, represents the horizontal forward distance at time t, represents the horizontal forward distance at the takeoff action start time.

[0116] The horizontal forward distance can be calculated by time integration of the ground speed or directly using the fused horizontal position sequence.

[0117] Further, in order to evaluate the minimum performance of the entire initial phase, all time points in the initial phase of the takeoff are traversed, the minimum value of all instantaneous net climb gradients is screened, and the minimum value is determined as the takeoff net climb gradient. The takeoff net climb gradient objectively and conservatively reflects the true obstacle clearance ability of the target aircraft in the most dangerous phase.

[0118] As an example, the minimum instantaneous net climb gradient in the initial phase of the takeoff can be determined by the equation , wherein inf represents the lower limit determination function.

[0119] The existing takeoff performance evaluation model assumes that the aircraft immediately establishes a positive climb rate after executing the takeoff instruction, ignoring two key physical processes: first, the height loss in the initial phase of the takeoff; second, when taking off at high altitudes or other special airports, the time required for the aircraft to accelerate to the target takeoff speed is significantly prolonged. In actual takeoff, due to the descent inertia and engine thrust establishment lag, the aircraft will continue to sink for a distance after the throttle is pushed to the takeoff position and the aircraft attitude begins to pitch up, until the energy state turns to positive climb. In extreme cases, such as low-altitude takeoff, it may cause the aircraft to touch the ground during the takeoff process. The initial height loss is particularly critical in complex terrain, low visibility, or unstable approach conditions, and ignoring this factor will lead to systematic overestimation of obstacle clearance ability, forming a non-conservative safety evaluation. The two factors work together to make the actual takeoff trajectory much lower than the theoretical prediction, and the existing model does not include these two dynamic effects, making it difficult to truly reflect the obstacle clearance margin and safety risk of the aircraft in the critical phase.

[0120] ​The embodiment of the present application divides the initial phase of the go-around from the start of the go-around action to the performance recovery of the go-around. By identifying the lowest height point in this phase, the actual height loss caused by the descent inertia and the thrust delay can be accurately quantified. In the calculation of the net climb gradient, this most dangerous "sinking" phase is included, so as to evaluate the performance of the aircraft in the phase of the lowest energy and the weakest obstacle clearance ability, avoid the systematic overestimation of the obstacle clearance ability caused by ignoring the height loss in the prior art, and make the safety evaluation more conservative and reliable.

[0121] In a preferred embodiment, the present application can further include the step of risk warning. Specifically, the go-around net climb gradient is compared with the minimum climb gradient required by the instrument procedure; if the go-around net climb gradient is lower than the minimum climb gradient, a go-around risk event warning is triggered.

[0122] Wherein, the minimum climb gradient required by the instrument flight procedure is, for example, the standard 2.5%. If the go-around net climb gradient is lower than the required minimum climb gradient, it indicates that the actual performance of the target aircraft in this phase fails to meet the safety design standard, at which time a go-around risk event warning can be triggered automatically to remind the safety management personnel to pay attention to this event.

[0123] In order to further realize the accurate attribution of risk, the present application can further include the steps of risk identification and attribution, which decouples the go-around risk into the control factor and the performance factor. Specifically, the minimum real takeoff height in the initial phase of the go-around is compared with the minimum takeoff height specified by the flight procedure to generate the obstacle clearance margin ratio of the initial phase; in the go-around climb phase constituted by the moment after the performance recovery of the go-around to the end point of the go-around procedure, the minimum net climb gradient is determined, and the minimum net climb gradient is compared with the minimum climb gradient required by the instrument procedure to generate the obstacle clearance margin ratio of the climb phase; based on the obstacle clearance margin ratio of the initial phase and the obstacle clearance margin ratio of the climb phase, the cause of the go-around risk is determined as the control factor risk or the insufficient aircraft performance risk.

[0124] It can be understood that the aircraft has not established a positive climb rate in the initial phase of the go-around, and the height may be temporarily decreased, and the safety boundary is mainly constrained by the minimum takeoff height specified by the procedure, that is, the lowest takeoff height margin is mainly focused on in this phase.

[0125] As an example, the obstacle clearance margin ratio of the initial phase can be calculated by the following formula :

[0126] ;

[0127] Wherein, represents the minimum takeoff height specified by the flight procedure.

[0128] The obstacle clearance margin ratio in the initial stage mainly reflects the pilot's manipulation quality at the start of the go-around. If the obstacle clearance margin ratio in the initial stage is too small, for example, less than a preset proportion threshold, there may be insufficient human manipulation, and the risk is attributed to the manipulation factor risk, which may be delayed thrust addition, improper attitude establishment, etc.

[0129] It should be noted that according to ICAO DOC 8168 and other relevant specifications, although the initial stage of the go-around allows the aircraft to have a short height loss due to the power restoration process, it must always ensure a minimum obstacle clearance of not less than 30 meters. Therefore, in the embodiments of the present application, the preset proportion threshold can be 0.8. When the obstacle clearance margin ratio in the initial stage is less than 0.8, that is, the actual height is less than 80% of the program requirement, the risk can be attributed to the manipulation factor risk.

[0130] In the go-around climb stage from the go-around performance restoration moment to the end point of the go-around program, the minimum net climb gradient of the stage is calculated and determined by calculating the net climb gradient of the initial stage of the go-around, and compared with the minimum climb gradient required by the instrument program, to generate the obstacle clearance margin ratio in the climb stage.

[0131] As an example, the obstacle clearance margin ratio in the climb stage can be calculated by the following formula :

[0132] ;

[0133] ;

[0134] wherein, represents the minimum net climb gradient of the go-around climb stage, represents the minimum climb gradient required by the instrument program, represents the horizontal forward distance at the go-around performance restoration moment.

[0135] The obstacle clearance margin ratio in the climb stage mainly reflects the system performance of the target aircraft in the stable climb configuration. If the ratio is too small, for example, the obstacle clearance margin ratio in the climb stage is less than 1, the risk can be attributed to the aircraft performance deficiency risk, which may be caused by aircraft overweight, abnormally high temperature, or strong tailwind, etc.

[0136] By dividing the go-around process into the initial stage of the go-around and the climb stage of the go-around, and calculating the corresponding obstacle clearance margin ratio in the initial stage and the obstacle clearance margin ratio in the climb stage, it can be clearly distinguished whether a high-risk go-around is caused by improper pilot manipulation or by insufficient performance of the aircraft in a specific environment, and the precise attribution of the risk cause is achieved. This attribution capability provides data-driven and operable decision support for optimizing pilot training, developing aircraft operation restrictions, and improving go-around program design.​

[0137] To construct a data-driven safety management closed loop, the method can further include the steps of event archiving and performance feedback. Specifically, the takeoff action initiation time, the performance reconstruction time, the initial stage obstacle clearance ratio, and the climb stage obstacle clearance ratio of each missed approach event are encapsulated into a structured missed approach event archive and archived; the historical archived multiple missed approach event archives are aggregated and analyzed to calculate safety performance indicators in different dimensions.

[0138] The key analysis results of each missed approach event are encapsulated into a structured missed approach event archive and stored in a database for archiving. The key analysis results such as the takeoff action initiation time, the performance reconstruction time, the initial stage obstacle clearance ratio, and the climb stage obstacle clearance ratio can also include flight number, aircraft type, airport, runway, and other operation metadata. Based on the historical archived multiple missed approach event archives, multi-dimensional aggregated analysis can be performed, such as calculating the high-risk missed approach occurrence rate of a specific airport runway, the manipulation risk rate of a specific crew, or the performance deficiency rate of a specific aircraft type at a high-altitude airport in a specific season, etc. These statistical results can provide strong data-driven decision support for pilot training, operation standard formulation, and safety management of airlines.

[0139] In an embodiment of the present application, for the i-th missed approach event, after risk identification and attribution of a single missed approach, the key analysis results of the event are encapsulated into a structured missed approach archive , including: missed approach initiation and performance reconstruction time, initial stage obstacle clearance ratio, climb stage obstacle clearance ratio, instrument approach procedure, risk warning, risk attribution, operating airport runway, aircraft type, and crew identification, etc. Through N historical missed approach events, a missed approach archive library can be formed.

[0140] Further, by the missed approach risk corresponding to each missed approach event in the missed approach archive library, the manipulation risk rate and the performance risk rate of the airport are determined, for example, the proportion of the number of missed approaches with manipulation factor risks to the total number of missed approaches is taken as the manipulation risk rate, and the proportion of the number of missed approaches with aircraft performance deficiency risks to the total number of missed approaches is taken as the performance risk rate.

[0141] Taking an A320 aircraft of an airline performing RNP APCH RWY 03 approach at an airport as an example. QAR data shows that the missed approach starts at RA=45 feet, which is lower than MAPt, the lowest field height in the initial stage is 28 feet, ; the climb stage obstacle clearance ratio is 0.84 due to high temperature. , The missed approach event is determined to be an aircraft performance deficiency risk, and is automatically archived and pushed to the high-altitude operation performance monitoring device.

[0142] The analysis results of each go-around event are structured and archived, and support multi-dimensional aggregation analysis and safety performance evaluation according to airports, fleets, crews, seasons, etc. This enables airlines and regulatory agencies to discover risk trends from massive historical data, identify systemic shortcomings, and upgrade passive analysis of single events to systemic and forward-looking safety risk management, thereby effectively improving overall flight safety.

[0143] The present application constructs a closed-loop early warning mechanism from data perception to safety decision, makes up for the shortcomings of static theoretical models, obtains accurate go-around net climb gradient, and automatically identifies high-risk go-around modes by calculating the obstacle clearance margin ratio at different stages, and then distinguishes whether the risk is caused by insufficient human operation or insufficient aircraft performance, thereby realizing accurate attribution of risk causes. A data-driven safety management tool is provided for airlines and regulatory agencies, thereby more effectively identifying and controlling operational risks during the go-around phase.

[0144] Please refer to Figure 2 The second embodiment of the present application is a go-around climb gradient determination system based on flight data, which is used to execute the above-mentioned go-around climb gradient determination method based on flight data, and includes a time recognition module 100, a flight path reconstruction module 200, and a climb gradient determination module 300.

[0145] The time recognition module 100 is used to recognize the go-around action start time and the performance reconstruction time of re-establishing stable climb ability based on the flight data of the target aircraft.

[0146] The flight path reconstruction module 200 is used to obtain the corrected aircraft geometric height of the target aircraft by correcting the non-standard atmospheric environmental factors and local geographical environmental factors affecting the aircraft geometric height based on the flight data, and reconstructing the corrected flight path in combination with the real-time horizontal position of the target aircraft.

[0147] The climb gradient determination module 300 is used to determine the go-around net climb gradient of the target aircraft in the initial go-around phase from the go-around action start time to the performance reconstruction time of the go-around action according to the go-around action start time, the performance reconstruction time of the go-around action, and the corrected flight path.

[0148] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and related description of the above-described system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0149] It should be noted that the above embodiment provides a flight data based aircraft reflight climb gradient determination method and system, and only the above functional modules are exemplified, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the modules or steps in the embodiment of the application are further decomposed or combined, for example, the modules of the above embodiment can be combined into one module, or can be further split into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present application are only for distinguishing various modules or steps, and should not be considered as an improper limitation of the present application.

[0150] The third embodiment of the present application is a device comprising:

[0151] at least one processor;

[0152] and a memory in communication connection with the at least one processor;

[0153] wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor to implement the above-mentioned flight data based aircraft reflight climb gradient determination method.

[0154] The fourth embodiment of the present application is a computer readable storage medium, which stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned flight data based aircraft reflight climb gradient determination method.

[0155] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and related description of the above-mentioned electronic device, computer readable storage medium and computer program product can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

[0156] Reference is made below to Figure 3 which shows the structure of the computer system of the server for implementing the system, method and electronic device embodiments of the present application. Figure 3 The server shown is only an example, and should not bring any limitation to the functions and use range of the embodiments of the present application.

[0157] As Figure 3As shown, the computer system includes a central processing unit (CPU) 301 which can perform various appropriate actions and processes in accordance with a program stored in a read only memory (ROM) 302 or a program loaded from a storage section 308 into a random access memory (RAM) 303. In the RAM 303, various programs and data required for the operation of the system are also stored. The CPU 301, the ROM 302, and the RAM 303 are connected to each other through a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0158] Connected to the I / O interface 305 are an input section 306 including a keyboard, a mouse, etc.; an output section 307 including a display such as a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 308 including a hard disk, etc.; and a communication section 309 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 309 performs communication processing via a network such as the Internet. A drive 310 is also connected to the I / O interface 305 as required. A removable recording medium 311 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc. is attached to the drive 310 as required, so that a computer program read out therefrom is installed in the storage section 308 as required.

[0159] In particular, according to embodiments of the present application, the processes described above with reference to the flowcharts can be implemented as a computer software program. For example, embodiments of the present application include a computer program product comprising a computer program carried on a computer readable medium, the computer program comprising program code for executing the methods illustrated by the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via the communication section 309, and / or installed from the removable medium 311. When the computer program is executed by the central processing unit (CPU) 301, the above-described functions defined in the methods of the present application are executed. Note that the computer readable medium described above in the present application can be either a computer readable signal medium or a computer readable storage medium or any combination of these two. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination of the above. More specific examples of the computer readable storage medium can include, but are not limited to, an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, the computer readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus or device. In the present application, the computer readable signal medium can include a data signal carried in a baseband or as part of a carrier wave, in which the computer readable program code is carried. Such a propagated data signal can take any of a variety of forms, including but not limited to electro-magnetic, optical, or any suitable combination thereof. The computer readable signal medium can also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate or transport a program for use by or in connection with an instruction execution system, apparatus or device. Program code contained in the computer readable medium can be transmitted by any suitable medium, including but not limited to wireless, wired, optical fiber cable, RF, and the like, or any suitable combination of these.

[0160] Computer program code for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0161] The computer program instructions can also be loaded onto a computer or other programmable information processing apparatus to cause a series of operations to be performed on the computer or other programmable information processing apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable information processing apparatus implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0162] The terms "first", "second", etc. are used to distinguish between similar objects, and are not used to describe or indicate a particular order or sequence among the objects.

[0163] The terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0164] The technical scheme of the present application has been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical schemes after the changes or replacements will all fall within the protection scope of the present application.

Claims

1. A method for determining the climb gradient of an aircraft during a go-around based on flight data, characterized in that, include: Based on the target aircraft's flight data, identify the start time of the go-around maneuver and the time of go-around performance reconstruction to re-establish stable climb capability; Based on the flight data, the corrected geometric altitude of the target aircraft is obtained by correcting non-standard atmospheric environmental factors and local geographical environmental factors that affect the aircraft's geometric altitude, and the corrected flight trajectory is reconstructed by combining the real-time horizontal position of the target aircraft. Based on the start time of the go-around maneuver, the time of go-around performance reconstruction, and the corrected flight path, the net climb gradient of the target aircraft during the initial go-around phase, which is formed by the start time of the go-around maneuver and the time of go-around performance reconstruction, is determined.

2. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The steps for identifying the start time of the go-around maneuver include: Acquire multiple flight parameters that reflect the aircraft status and control inputs, wherein the flight parameters include at least the thrust handle angle, flight control computer mode, and aircraft pitch angle; When the flight parameters simultaneously meet the preset go-around trigger conditions, the current time is determined as the start time of the go-around action. The go-around trigger conditions include the thrust handle angle increasing within a preset duration and exceeding the go-around thrust threshold, the flight control computer mode being switched to go-around mode, and the aircraft pitch angle increasing within a preset duration and exceeding the nose lift threshold.

3. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The steps for identifying the time of re-entry performance reconstruction include: After the start of the go-around maneuver, the moment when the target aircraft first simultaneously meets the predefined performance establishment conditions is determined as the go-around performance reconstruction moment; wherein, the performance establishment conditions include the target aircraft's geometric altitude exceeding the altitude at the start of the go-around maneuver, the flight speed reaching a preset reference speed, the vertical speed remaining positive for a preset duration, and the pitch angle reaching a preset climb attitude angle.

4. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The step of obtaining the corrected geometric altitude of the target aircraft includes: Atmospheric static pressure is obtained by inverting the barometric altitude recorded by the airborne system; Based on measured atmospheric temperature and ambient humidity information, the effective gas constant of air affected by water vapor is obtained; Based on the geographical latitude and altitude of the target aircraft, determine the local gravitational acceleration value; By combining the atmospheric static pressure, the effective gas constant, the local gravitational acceleration value, and the measured static temperature, the corrected geometric altitude of the aircraft, reflecting the true physical altitude, is derived by solving the hydrostatic equilibrium equation.

5. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 4, characterized in that, The step of obtaining the corrected geometric altitude of the target aircraft further includes: When the target aircraft is flying at a low altitude near the ground, the true altitude of the aircraft relative to the ground, measured by a radio altimeter, will be used as the corrected geometric altitude of the target aircraft.

6. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The reconstructing and correcting of the flight trajectory based on the real-time horizontal position of the target aircraft includes: Provided that the signal quality of the Global Positioning System meets the preset reliability standard, the location data provided by the Global Positioning System is used as the real-time horizontal position of the target aircraft. If the signal quality of the Global Positioning System does not meet the preset reliability standard, the position data calculated by the inertial navigation system is used as the real-time horizontal position of the target aircraft.

7. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The steps for determining the net climb gradient during the initial phase of the go-around include: At any point during the initial phase of the go-around, the obstacle elevation corresponding to the real-time horizontal position of the target aircraft is obtained; The difference between the corrected geometric altitude of the aircraft and the elevation of the obstacle at any given moment is obtained as the net vertical margin of the target aircraft at any given moment. The ratio of the net vertical margin to the horizontal advance distance is calculated as the instantaneous net climb gradient at any given moment, wherein the horizontal advance distance is the horizontal distance traveled by the target aircraft since the start of the go-around maneuver. The minimum value among all instantaneous net climb gradients during the initial phase of the go-around is determined as the net climb gradient for the go-around.

8. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The method further includes: Compare the net climb gradient of the re-flight with the minimum climb gradient required by the instrument program; If the net climb gradient for the go-around is lower than the minimum climb gradient, a go-around risk event alarm will be triggered.

9. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 1, characterized in that, The method further includes: The minimum actual ground clearance during the initial phase of the go-around is compared with the minimum ground clearance specified in the flight procedure to generate the initial phase obstacle clearance margin ratio. During the go-around climb phase, which is defined from the moment of go-around performance reconstruction to the end of the go-around procedure, the minimum net climb gradient is determined, and the minimum net climb gradient is compared with the minimum climb gradient required by the instrument program to generate the climb phase obstacle clearance margin ratio. Based on the initial obstacle clearance margin ratio and the climb obstacle clearance margin ratio, the cause of the go-around risk is determined to be either control factor risk or aircraft performance inadequacy risk.

10. The method for determining the climb gradient of an aircraft go-around based on flight data according to claim 9, characterized in that, The method further includes: The start time of the go-around maneuver, the time of go-around performance reconstruction, the obstacle clearance margin ratio in the initial phase, and the obstacle clearance margin ratio in the climb phase of each go-around event are encapsulated into a structured go-around event file and archived. Multiple historical archives of go-around incidents were aggregated and analyzed to calculate safety performance indicators under different dimensions.

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