Purpose

The purpose of this paper is to present a comparative study of flight circumstances, dynamic stability characteristics and controllability for two transport aircraft in severe atmospheric turbulence at transonic cruise flight for the purpose to obtain the prevention concepts of injuries to passengers and crew members for pilot training in International Air Transport Association (IATA) – Loss of Control In-flight (LOC-I) program.

Design/methodology/approach

A twin-jet and a four-jet transport aircraft encountering severe atmospheric turbulence are the study cases for this paper. The nonlinear unsteady aerodynamic models are established through flight data mining and the fuzzy-logic modeling technique based on the flight data of flight data recorder. This method can be adopted to examine the influence of horizontal wind shear and crosswind on loss of control, dynamic stability characteristics and controllability for transport aircraft in different weights and different sizes in tracking aviation safety of existing different types of aircraft.

Findings

The horizontal wind shear or crosswind before the turbulence encounter will easily induce rolling motion and then initiate the sudden plunging motion during the turbulence encounter. The roll rate will increase the oscillatory rolling motion during plunging motion, if the rolling damping is insufficient. The drop-off altitude will be enlarged by the oscillatory rolling motion during the sudden plunging motion.

Research limitations/implications

A lack of the measurement data of vertical wind speed sensor on board to verify the estimated values of damping term is one of the research limitations for this study. The fact or condition of being severe in sudden plunging motion can be judged through the analysis of oscillatory derivatives with both dynamic stability and damping terms.

Practical implications

The roll rate will increase the oscillatory rolling motion during plunging motion, if the rolling damping is insufficient. The drop-off altitude will be enlarged by the oscillatory rolling motion during the sudden plunging motion. The horizontal wind shear or crosswind before the turbulence encounter will easily induce rolling motion and then initiated the sudden plunging motion during the turbulence encounter. If the drift angle is large, to turn off the autopilot of yaw control first and stabilize the rudder by the pedal. When passing through the atmosphere turbulence area, the pilots do not need to amend the heading angle urgently.

Social implications

The flight safety prevention in avoidance of injuries for passengers and cabin crews is essential for the airlines. The horizontal wind shear or crosswind before the turbulence encounter will easily induce rolling motion and then initiated the sudden plunging motion during the turbulence encounter.

Originality/value

The flight safety prevention in avoidance of injuries for passengers and cabin crews is essential. The present assessment method is an innovation to examine the loss of control problems of aviation safety and promote the understanding of aerodynamic responses of the jet transport aircraft. It is expected to provide a valuable lecture for the international training courses for IATA – LOC-I program after this paper is being published.

中文翻译：

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喷气运输机响应剧烈大气湍流的突然俯冲运动的严重性评估

目的

本文的目的是对两架运输机在跨音速巡航飞行中强大气湍流中的飞行工况、动态稳定性特性和可控性进行对比研究，以期获得飞行员培训中防止乘客和机组人员受伤的理念。国际航空运输协会 (IATA) – 飞行中失控 (LOC-I) 计划。

设计/方法论/途径

遭遇严重大气湍流的双喷和四喷运输机是本文的研究案例。基于飞行数据记录仪的飞行数据，通过飞行数据挖掘和模糊逻辑建模技术建立非线性非定常气动模型。该方法可用于检验水平风切变和侧风对不同重量、不同尺寸运输机失控、动态稳定特性和可控性的影响，跟踪现有不同型号飞机的航空安全。

发现

遇到湍流之前的水平风切变或侧风很容易引起横滚运动，然后在遇到湍流时引发突然的俯冲运动。如果滚动阻尼不足，滚动速率将增加切入运动期间的振荡滚动运动。突然下降运动期间的振荡滚动运动将扩大下降高度。

研究局限性/影响

缺乏船上垂直风速传感器的测量数据来验证阻尼项的估计值是本研究的研究局限性之一。通过分析具有动态稳定性和阻尼项的振荡导数可以判断突然猛烈运动的事实或情况。

实际影响

如果滚动阻尼不足，滚动速率将增加切入运动期间的振荡滚动运动。突然下降运动期间的振荡滚动运动将扩大下降高度。遇到湍流之前的水平风切变或侧风很容易引起滚动运动，然后在遇到湍流时引发突然的俯冲运动。如果漂移角较大，应先关闭偏航控制自动驾驶仪，然后通过踏板稳定舵。当经过大气湍流区时，飞行员无需紧急修正航向角。

社会影响

防止乘客和机组人员受伤的飞行安全预防对于航空公司至关重要。遇到湍流之前的水平风切变或侧风很容易引起滚动运动，然后在遇到湍流时引发突然的俯冲运动。

原创性/价值

飞行安全预防以避免乘客和机组人员受伤至关重要。本评估方法是检查航空安全失控问题并促进对喷气运输机气动响应的理解的创新。预计本文发表后将为IATA-LOC-I项目国际培训课程提供有价值的讲座。