An Investigation of Sudden Plunging Motion Mechanisms for Transport Aircraft during Severe Clear-Air Turbulence Encounter

The main purpose of this paper is to study the flight dynamic mechanism that induced the sudden plunging motion for jet commercial transport in transonic flight during a severe clear-air turbulence encounter. The study of flight dynamic mechanism is to obtain the mitigation concepts for pilot training in loss of control prevention of the IATA program. The comparative analyses of flight environment and pilot control response to severe clear-air turbulence encounter for two similar twin-jet aircraft and two four-jet aircraft are studied. The one with highest dropped-off altitude during the sudden plunging motion among the four will be chosen to construct the flight dynamic mechanism. The nonlinear and dynamic aerodynamic models of the chosen transport are established through flight data mining and the fuzzy-logic modeling based on postflight data. The influences of varying vertical wind and crosswind on loss of control are presented. The source of significant angles of attack to be induced by the crosswind during the sudden plunging motion is proved through the flight dynamic analysis based on model predicted data. The present study is initiated to examine possible mitigation concepts on loss of control prevention in pilot training of IATA.