Study On Triggered Warning Of Enhanced Ground Proximity Warning System On Terminal Area Under Low Temperature Environment Based On Digital Elevation Model

Controlled Flight Into Terrain?CFIT?accounts for a large part of air accidents^[1].According to foreign statistical data,CFIT is responsible for a large part of the deaths of commercial airliners.During the critical stage of take-off and landing in the terminal area,the influence of low temperature on the pressure altitude has always been an inevitable potential threat,leaving hidden trouble for obstacle clearance and other problems.According to the investigation,after years of operation,there still exists the situation that the GPWS warning triggered in terminal area due to low temperature,which constitutes an unsafe event and has the potential risk of causing CFIT.In order to reproduce and quantitatively analyze such unsafe events and determine the general area and range of trigger warning,a warning trigger algorithm for GPWS was proposed to reduce the risk of controlled flight into terrain incidents.Based on the performance software,the take-off track in the terminal area was simulated and the vertical and horizontal track of the designated departure route and the GPS with required relevant data information is obtained.Based on the Digital Elevation Model?DEM?,the terrain data was analyzed and the required terrain data was screened out according to the simulated track information.Based on the warning envelope of specific mode of the Enhanced Ground Proximity Warning System?EGPWS?mass-produced by Honeywell,the parameters of warning trigger were modeled,and the warning trigger algorithm of GPWS was proposed.Compared with the warning envelope,the parameters and GPS data information were searched,and the GPS data and geographical range where the warning was triggered were quantitatively determined.Algorithm based on Matlab platform,the take off track of ZULS airport in Lhasa was simulated during the extreme low temperature environment and the data of take-off track was compared to the warning envelope of EGPWS specific mode.The results showed whether the warning was triggered and the GPS data and geographical range where the warning was triggered was searched.The take-off track of ZWWW airport during the low temperature environment was verified.The results show that it is of certain value for the future recurrence of such unsafe events or accidents,and it can predict the trigger area to a certain extent,which has reference significance for the improvement of safety margin.