Table of Content

17 November 2025, Volume 43 Issue 5

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Safety and airworthiness of civil aircraft

Research on airworthiness technology and standards for low-altitude equipment

based on system safety

DING Shuiting , QI Lei a , LI Guob , QIU Tiana , LI Daqing

2025, 43(5):  1-15. 

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With the continuous emergence of new scenarios and technologies in the low-altitude field, the effectiveness of

previous experience with airworthiness standards for traditional aircraft configuration has significantly diminished. Thus, it is urgent to establish an airworthiness standard system that meets the development needs of low altitude aircraft in the future. This paper systematically reviewed the current status and future trends of airworthiness standards for low-altitude equipment both domestically and internationally, and detailedly analyzed the development history and current situation of safety technologies in the aviation field. On this basis, a new airworthiness standard system framework for low-altitude equipment was proposed, with features of system safety leadership, object type independence, safety effect-based regulations, and multiple compliance pathways. This framework helps to address issues such as low-altitude new scenarios, new technologies, their complexity, diversity,

and rapid evolution. It provides guidance and framework suggestions for the construction of low-altitude equipment airworthiness standard system, and offers strong support for implementing China's approach to next-generation international airworthiness standards.

Identification of causal factors and analysis of mechanism of action of near mid-air collision incident

CHEN Fang , LI Jiarui , SHEN Ruiyu

2025, 43(5):  16-23. 

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In order to help safety managers understand the occurrence mechanism of near mid-air collision incident and

clarify the relationship and importance of causal factors, a model for identifying the causal factors of near mid-air

collision incident and analyzing its potential mechanism of action is proposed. Latent Dirichlet allocation (LDA)

topic model is used to identify causal factors from incident reports and lists of hazard source, the decision-making trial and evaluation laboratory and interpretative structural model (DEMATEL-ISM) is constructed, the influence relationships among factors are clarified, the importance and attributes of each factor are determined, a

multi-level hierarchical structure model is constructed to visually display the direct, indirect, and fundamental

causes of the incident. The results show that 33 causal factors are identified, including poor risk management and

control of abnormal operation, among which wrong instruction issued by command seat is the direct cause, directly leading to the occurrence of the incident. The poor performance of dual position system is an indirect cause,

which has a relatively small direct impact, but has a significant interactive coupling effect with other factors. In adequate safety and operational training are the fundamental causes, and improving them is conducive to reducing the occurrence of near mid-air collision incident from the root. Near mid-air collision incidents are the result

of the combined effects of direct, indirect, and fundamental causes, based on this, specific countermeasures and

suggestions are proposed from the perspective of air traffic management.

Flight security threat posture assessment model based on SPA-Markov chains

LIU Lingli, SUN Yeting, WAN Jiali

2025, 43(5):  24-30. 

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In order to assess the level of flight security threats as well as analyze and predict their developmental trend, an

assessment model of flight security threat posture based on set-pair analysis (SPA) and Markov chains was proposed. Firstly, evaluation index system of the flight security threat posture was constructed based on the occurrence posture of various types of in-flight cases (incidents), and the combined weights of the indicators were determined by integrating the calculation results of the gray correlation coefficient method and the entropy weighting method. Subsequently, by integrating the ternary connection number structure in the SPA theory and the civil

aviation risk classification standards, the level of flight security threat was classified into three levels. By calculating the connection degree, the flight security threat level and the development trend were determined, and by

combining it with the Markov state transition probability matrix, the future level of flight security threat was dynamically predicted. Finally, the proposed model was validated using 2021 in-flight cases (incidents) data. The

results indicated that the model can reflect the status of flight security threat.

Evaluation and application research of psychomotor ability of civil aviation pilots

2025, 43(5):  31-36. 

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Psychomotor ability is the basic ability guarantee for pilots to master flight skills. This study proposed a psychomotor ability assessment method based on multiple object tracking tasks for pilots and verified the application of the

method. Firstly, 309 subjects including flight cadets from aviation schools and pilots from airlines were recruited as

participants and conducted psychomotor ability evaluation from 4 dimensions. Subsequently, statistical methods

were employed to conduct item analysis, content validity testing, and correlation analysis on the measurement data.

The result showed that although there were some dimensions of measurement data not following normal distribution, the discriminability of all four dimensions of assessment items exceeded 0.40, indicating that the method exhibits good content validity. Significant differences in psychomotor abilities were found among pilots from different

groups of subjects (p < 0.05). There was a strong correlation between the total score of psychomotor ability and

each dimension, which demonstrating the excellent content validity of the evaluation method. This study further

validated the feasibility and reliability of the evaluation method in pilot psychomotor ability evaluation.

Statistical analysis and consequence prediction of aircraft runway excursion accidents

CAI Jing, ZHOU Ning, WANG Yan, DAI Xuan, LI Yue

2025, 43(5):  37-43. 

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In order to study the main characteristics of the occurrence and consequences of aircraft runway excursion accidents, 100 global aircraft runway excursion accidents from 2010 to 2019 were statistically analyzed in this paper,

and the regularity of aircraft runway excursion accident was deeply analyzed from the aspects of accident types,

accident causes, accident spatiotemporal distribution, aircraft types involved in accidents, and accident consequences. Based on back propagation (BP) neural network, a prediction model of the consequences of aircraft

runway excursion accidents was constructed to predict the severity of accident consequences under different

conditions. The results showed that veering off runway accidents were the main aspect of aircraft runway excursion accidents, wet, slippery and polluted pavement and crosswind were the main causes of accidents. Aircraft

runway excursion accident had strong spatiotemporal distribution regularity, and different influencing factors can

cause varying degrees of consequences and losses. The prediction model constructed in this article achieved a

prediction accuracy of 76.67% for the consequences of aircraft runway excursion accidents, and the accuracy of

the test set and training set reach the same level, indicating that the model has good predictive performance and

can provide early-warning basis for aircraft landing safety management.

Research on risk assessment of classification and grading security inspection for

aviation express

ZHAO Zhenwu, LI Yanjiao

2025, 43(5):  44-50. 

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To cope with the increasing demand for security inspection for aviation express, ensure the timeliness of aviation

express transportation, and achieve efficient security inspection and safe transportation of aviation express, on the

basis of the traditional security inspection mode, a classification and grading security inspection mode for all cargo aircraft aviation express is firstly proposed in this paper, and the risk assessment of the security inspection

system is conducted from three aspects, including threat, vulnerability, and consequence severity. Secondly, this

paper mainly combines the search-decision model and the work performance model of security inspector to

quantitatively calculate the vulnerability indicator missing rate, and the data of threat and consequence severity

indicators are derived from the statistical laws of accident data. The risk assessment results indicate that the risk

value of the classification and grading security inspection system for full cargo aircraft aviation express is reduced

by 29.77% compared to the traditional express security inspection systems, and increasing the time for security

inspectors to judge images within the time interval has little impact on the system′s missed detection rate and

false detection rate. This can provide theoretical guidance for implementing classification and grading security

inspection strategies for full cargo aircraft.

Future airports and smart equipment

Geocell-reinforced soil pavement and the finite element analysis of mechanical

response

ZHANG Xinfang , MA Lukuan , ZHAO Leiming , LIAO Yu , GUO Fei

2025, 43(5):  51-57. 

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To investigate the reinforcement effect and its mechanical response law of geocell-reinforced soil pavement, this

study selected the geocell-reinforcement material of Germany Novus. The effect of strengthening soil pavement

with geocell was tested by testing the resilient modulus of the pavement through the bearing plate experiment.

Firstly, using the finite element simulation method, a finite element analysis model for the mechanical response of

the geocell-reinforced soil pavement was established and validated. Secondly, by selecting typical aircraft load

effects and structural parameters of the geocell-reinforced pavement, the mechanical response sensitivity and

mechanical response law of the geocell-reinforced soil pavement were analyzed using the maximum vertical compressive strain, maximum vertical displacement, and depth of the roadbed working area as analysis indicators.

The results demonstrate that under 90% compaction degree, the resilient modulus of the geocell-reinforced soil

pavement increased by 23.7%. The subgrade resilient modulus has the most significant impact on the maximum

vertical compressive strain and maximum vertical displacement of the structure of geocell-reinforced soil pavement. The maximum vertical compressive strain decreased with increasing subgrade resilient modulus, geocell elastic modulus and thickness, but increased with increasing geocell cutout size. The maximum vertical displacement of the pavement is closely related to the weight of a single wheel of the aircraft main landing gear, and heavier aircraft will increase the maximum vertical displacement. The parameters of the pavement structure have no significant effect on the depth of the roadbed working area, and there is a linear positive correlation between the depth of the roadbed working area and the weight of a single aircraft main landing gear. This study can provide

reference for the design and development of geocell-reinforced soil pavement.

Random dynamic load identification based on atrous convolutional neural network

WANG Wei, XU Bufeng, HE Wenbo, DI Zekun, SUN Hanyu

2025, 43(5):  58-63. 

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To address the issue of low accuracy in random dynamic load identification, the atrous convolutional neural network (ACNN) is introduced into the research of random dynamic load identification. A random dynamic load

identification method based on one-dimensional ACNN with a dilation rate of 2 is proposed, which increases the

signal receptive field by increasing the dilation rate, thereby improving the accuracy of load identification. The

load identification verification experiment is conducted using the GARTEUR aircraft model as the research object, and the results show that the root mean square error between the random dynamic load on the wingtip excitation point identified by the method in this article and the real load is 0.990 1 N, with a correlation coefficient

of 0.987 4, and the power spectral density (PSD) curve can match well. Under different levels of noise interference, the proposed method can effectively identify the time series of random dynamic load. The proposed

method has the advantages of high recognition accuracy and strong anti-interference ability.

Study on low-temperature sealing characteristics of series VL-type seal of

retracting and releasing actuator of landing gear

WEI Jian, LIU Luzhuo, TIAN Jing, LIU Yuhang

2025, 43(5):  64-72. 

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In order to study the sealing characteristics of series VL-type seal in low temperature ambient, firstly, this paper

takes the series VL-type seal for the retracting and releasing actuator of a certain type of aircraft landing gear as an

example, test the stress-strain data of seal material of polytetrafluoroethylene and nitrile butadiene rubber under

different ambient temperatures. Secondly, the finite element analysis software ABAQUS is used to establish a two dimensional axisymmetric model of series VL-type seal, and a mixed lubrication model of reciprocating series VLtype seal is established. Taking friction force and leakage as evaluation indicators, the influence of ambient temperature, medium pressure and reciprocating speed on sealing characteristics is analyzed based on actual working

conditions. The results show that with the decrease of ambient temperature, the resilience of the VL-type seal decreases, the contact pressure and contact width of the sealing surface are decrease, the intermediate pressure increases, and the net leakage increases. With the increase of the reciprocating speed, the dynamic pressure effect of

fluid increases, the oil film thickness increases, the friction force decreases, and the net leakage increases. With

the increases of medium pressure, the contact pressure and friction force of the series VL-type seal in increases,

and net leakage increases.

Aerodynamics

The numerical simulation of boundary layer ingestion fan based on body force

model

YANG Xiaojuna , YU Siyingb , KONG Qingguob

2025, 43(5):  73-81. 

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There is a complex distorted flow field at the inlet of boundary layer ingestion (BLI) fan, but most of the existing

research are limited to traditional three-dimensional simulation methods, which are time-consuming. This article

takes the DGEN380 fan rotor as the research object and designs an S-shaped inlet that matches it to ingest incoming boundary layer, and a calculation method based on the body force model (BFM) is adopted. The trend of

parameter changes in the calculation results is well consistent with the unsteady calculation results. The circumferential average values of the swirl angle and dimensionless total pressure at the fan inlet deviate from the unsteady

results within 6%, and the calculation time is 1/50 of that of the unsteady method. Based on this model, the influence of three different thicknesses of BLI at inlet heights of 15%, 30%, and 60% on the flow field at the inlet and

outlet of the fan rotor is explored. The results show that, for the fan rotor inlet, the degree of total pressure distortion and swirl distortion increases with the BLI thickness increasing at different blade heights, and the swirl distribution presents a paired vortex form. After passing through the fan rotor passage blades, the paired vortexes

gradually transform into a unidirectional vortex, and the backward angle of the airflow at the fan rotor outlet decreases. The power coefficient value of BLI fan has been improved compared to the uniform flow condition.

Air Transport Economics

Estimation method of sell-up potential based on the stochastic nature of

passengers′ willingness to pay

FAN Wei , ZHANG Yongxiang

2025, 43(5):  82-89. 

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Regarding the issue that the stochastic nature of passengers′ willingness to pay is neglected by the sell-up potential estimation method of the Massachusetts Institute of Technology, which results in the underestimation of

the demand for intermediate class cabin, a sell-up potential estimation method that takes into account the probability distribution law of passengers′ willingness to pay was proposed. Firstly, assuming that passengers′ willingness to pay follows a normal distribution. Then, based on its probability characteristics, an estimation model

for sell-up potential was derived. Subsequently, the parameters of the distribution of passengers′ willingness to

pay were fitted from historical data to realize the estimation of the sell-up potential. To validate the effectiveness

of the proposed method, this article draws on the famous simulation system ideas from abroad, using Gaussian

mixture distribution to statistically analyze the data of passengers arrival, and a flight passenger arrival simulation software was designed and implemented for simulation evaluation. The system simulation combining real

data from three representative flight routes showed that the method proposed in this paper can effectively

strengthen the control of intermediate-class cabin and increase flight revenue.

Basic Science

Correspondence relationship between simplex table and mathematical model

ZHANG Baocheng a, KANG Shuai a, b

2025, 43(5):  90-96. 

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Existing studies can not well show the relationship between mathematical principles and calculation steps of the

simplex table. The mathematical principle of the simplex algorithm can be effectively demonstrated from the perspective of the one-to-one correspondence relationship between the simplex table and the mathematical model.

According to the coefficients of the entering variable in the constraint conditions, the determination method of the

maximum value of the entering variable and the determination method of the leaving variable were proposed, and

then the model iterative algorithm was established. Case analysis showed that, compared with simplex table iteration, model iteration can more clearly show the mathematical principle of the simplex algorithm.