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Quick Access Recorder (QAR) Data Analysis Software for
Windshear and Turbulence Studies
H. Haverdings1
National Aerospace Laboratory NLR, Anthony Fokkerweg 2, 1059 CMAmsterdam, The Netherlands
and
P.W. Chan2
Hong Kong Observatory, 134A Nathan Road, Kowloon, Hong Kong, China
For analysis of low-level windshear and turbulence events at the Hong Kong
International Airport (HKIA), besides pilot reports routinely received from Air Traffic
Control, Quick Access Recorder (QAR) data are obtained from the local airlines by the
Hong Kong Observatory (HKO). Instead of using directly the wind data recorded on the
aircraft by the flight management system (FMS), there has been a collaborative study
between HKO and the National Aerospace Laboratory (NLR) in The Netherlands to develop
a QAR data analysis software to calculate the meteorological quantities, such as the three
components of the wind, windshear hazard factor and turbulence intensity parameters,
taking into account the aircraft’s aerodynamic factors (e.g. sideslip angle, angle-of-attack).
This paper describes the main features of the calculation software, named WINDSTURB,
and illustrates its application to windshear and turbulence studies through selected cases at
HKIA.
Nomenclature
a0 – a3 calibration coefficients Y side/lateral force
Ay lateral acceleration α angle of attack
cy force coeffi cient ofY-force β sideslip angle
D drag  true track angle
DME Distance Measuring Equipment F fl ap angle
EPR Engine Pressure Ratio ε1/3 eddy dissipation rate (EDR)
FMS FlightManagement System  (non-dim.) vorticity
GS groundspeed  bias in acceleromet er, co-state vector
ILS Instrument Landing System
w   standard deviation of vertical wind variations
LIDAR Light Intensifying Detection And Ranging  time lag
m aircraft mass ω1, ω2 cut-off frequencies in the calculation of EDR
QAR Quick Access Recorder superscripts
S surface area b Body
TKE Turbulent Kinetic Energy e Earth
Twndw window time interval subscripts
V inertial speed fin tailfin
Va airspeed fus fuselage
Vw wind speed impr improved
WVE Wake Vortex Encounter wndw window
x,y,z position coordinates
1 National Aerospace Laboratory, Anthony Fokkerweg 2, 1059 CMAmsterdam, The Netherlands.
2 Hong Kong Observatory, 134A Nathan Road, Kowloon, Hong Kong, China.
1st AIAA Atmospheric and Space Environments Conference
22 - 25 June 2009, San Antonio, Texas
AIAA 2009-3871
Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
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1 Introduction
UE to terrain effect and land-sea interaction, landing and departing aircraft at HKIA could experience low-level
windshear and turbulence (viz. occurring below 1,600 feet). On average, 1 in 500 flights at HKIA reports
encountering signifi cant windshear (headwind/tailwind change of 15 knots or more) and 1 in 2,000 flights reports
significant turbulence (moderate or severe). To capture the wind fluctuations, a suite of ground-based and remote
sensing meteorological instruments is operated by HKO, including the conventional anemometers, weather buoys,
radar wind profilers, a Terminal Doppler Weather Radar (TDWR) and two LIght Detection And Ranging (LIDAR)
systems. Based on the data collected by these instruments, a number of windshear detection algorithms have been
developed by HKO and put into operational use at HKIA. Turbulence detection algorithms are under development
as well.
In the development and verification of the above algorithms, the pilot reports are normally used as “ sky truth”.
However, it is commonly accepted that the pilots’ perception of windshear and turbulence is subjective and there
could be discrepancies among the reports themselves because there is no “ uniform practice” on how to determine
windshear and turbulence despite the best efforts by pilots. Different pilots may refer to different elements in the
reporting, such as airspeed or speed trend, indicated by a trend vector arrow available on certain ai rcraft types only.
In order to build up an objective database of windshear and turbulence cases for developing detection algorithms,
HKO has taken on two steps: (a) to obtain QAR data routinely from the local airlines, and (b) to arrange a
collaborative study with an established aerospace laboratory for developing software to process the QAR data and
obtain the required meteorological quantities by taking into account the aerodynamic factors of the aircraft types
commonly operated by the local airlines. The meteorological parameters for studies of low-level windshear and
　
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