Performance Evaluation of an Airborne Coherent Doppler Lidar and Investigation of Its Practical Application

• Published in: TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES Vol. 65; no. 2; pp. 47 - 55
• Main Authors: AKIYAMA, Tomohiro, INOKUCHI, Hamaki
• Format: Journal Article
• Language: English
• Published: Tokyo THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 01.01.2022; Japan Science and Technology Agency
• Subjects: Accidents; Air Turbulence; Aircraft; Aviation Accident; Backscattering; Control methods; Control surfaces; Deceleration; Flight Safety; Flight Testing; High altitude; Japanese space program; Jet aircraft; Lidar; Onboard Sensor; Performance evaluation; Turbulence
• ISSN: 0549-3811; 2189-4205
• DOI: 10.2322/tjsass.65.47

The Japan Aerospace Exploration Agency (JAXA) has developed an airborne turbulence detection system based on coherent Doppler lidar (CDL) as a way to reduce the number of turbulence-induced accidents. A flight experiment with a jet aircraft measured and compared how the aerosol particle concentration in the atmosphere correlated with the laser backscatter coefficient and maximum observation range at different altitudes. Although we verified that the turbulence detection range of the CDL was sufficient to be able to issue go-around advisories to avoid windshear during approach, its short range at high altitudes is likely to limit its effectiveness at providing advance warning of turbulence when cruising. In order to mitigate turbulence-induced accidents, it is possible to use CDL as a sensor to acquire preview information for gust alleviation control. However, there are still technical issues to be solved in general control by control surfaces, so automatic deceleration is a more realistic control method. Generally, deceleration reduces the severity of aircraft motions induced by turbulence. Based on these results, we propose the basic specifications of a CDL that will be effective in mitigating turbulence accidents and its practical use.