Development of an Onboard Doppler LIDAR
for Flight Safety
Hamaki Inokuchi and Hisamichi Tanaka(Japan Aerospace Exploration Agency)
Toshiyuki Ando
(Mitsubishi Electric Corporation)

Contents• Aviation Accidents• Onboard Doppler LIDAR• 1NM Model
1NM = 1852 m• 3NM Model• 5NM Model• Plans for the Near Future• SummaryAviation Accidents

Large civil airplane in Japan (1990～2006)(Parentheses are the number of personnel accidents)
Operational Accidents
In-flight Accidents
Disease10 (10)Wind turbulence
25 (25)

Human Ongroundfactor fire
10 (6) 6 (5)Accidents
DeathSeriousinjury
News

Minorinjury(25)
Turbulence
OperationalPersonnel(36)≒70%Minor injury ≠ Accident
Frequent

Turbulence Accident Prevention
Prior information
・Weather forecast: Invalid for the small area on enroute
・Weather RADAR: Invalid for the clear air turbulence
・Information from precedence: Invalid for the short time change

Damage reduction
・Seat belt: Difficulty in the cabin service
・Gust alleviation: Invalid for the initial shake・Interruption of the cabin service: Much time is required
・Evasion flight: Prior reliable information is required
If turbulence is predicted beforehand,these measures become more effective.

Onboard Doppler LIDAR

Scattering by aerosol

WindLaser

LIDAR: Light Detection And Ranging
Overall Concept of the Onboard Wind Measurement LIDAR

Onboard Doppler LIDAR
Emission
Masterlaser

Fiberamplifier
Reference light
Signalprocessor

DisplayWind data

Photosensor

Opticalantenna
Backscatter
Backscattered
light

Beat signal

Block Diagram of Coherent Doppler LIDAR
Based on Optical Heterodyning TechniqueAdopted Method

Optical fiber amplifier・Small：Optical devices are small, power-saving and ahuge chiller is unnecessary
・High reliability：Dust-proofness and low EM noise・Flexible layout：Separate installation is possible
・Eye safety: 1.5μm is the safest wavelength

Suitable as an onboard system

2001

1NM Model
Telescope

Optical antenna

Laser transceiver
Opticalfiber
Signal processor

2006

Installation (3NM Model)
Optical antenna

Laser window
L AS E R

Excitation light generator
Beechcraft Model 65
Power supply

Laser transceiverWind velocity(m/s)

Flight Test Data (3NM Model)

ValidDetectability(dB)

Invalid

Noise levelRange (km)

True airspeed by LIDAR (m/s)

Flight Test Data (3NM Model)
In gusty areaTolerance in FAR 23.1323(3% or 5 kt)

True airspeed by Pitot static tube (m/s)

Measured Standard
rangedeviation(m)(m/s)
450-600
0.63
600-7500.68

750-900

0.69

900-1050

0.70

Equivalentaccuracy to thePitot tube

00

Range [km]Wind speed [m/s]615Flight Test Data (3NM Model)

02040
Measured data

Time [s]60615Flight Test Data (3NM Model)

00

Range [km]Wind speed [m/s]

Omit the Detectability < 4.5dB

02040
Cleaned data

Time [s]60Flight Test Data (3NM Model)

Verticalacceleration (G)Range (km)5Fh-factor <0.03, =0.03～0.06, >0.06

01Prediction

0-10204060 Time (s)Turbulence Prediction

5NM Model

PC

2007

Optical antenna

Excitation
light generator
Laser transceiver
Ground testequipment

Ground Test Result
1NM
model
3NM
model
5NM
model

Noise level

Installation (5NM Model)

2008

Laser window
LASER

Dornier Model 228

Specifications

Laser peak power
Laser pulse energy
Pulse repetition frequency
Aperture diameter
Power consumption
Weight1NMmodel(2001)
10 W
4.5μJ
50 kHz
50 mm
420 W
105 kg3NMmodel(2006)
90 W
58μJ4 kHz
110 mm306 W
51 kg

5NMmodel(2007)
323 W
179μJ
4 kHz
110 mm374 W
82 kg

Plans for the Near Future

・Flight demonstration of the 5NM model isplanned in March 2009
・Development of a 5NM high altitude modelis planned in February 2009
・High altitude demonstration using a jet
plane is planned in 2009

5NM high altitude modelHigh power
amplifier(835μJ)
Telescope

Optical antenna

2009Summary

・Turbulence accidents are frequent.
・Range of 3NM was demonstrated in flight.
・LIDAR has sufficient accuracy as a sensor.
・Range of 5NM was demonstrated on ground.
・Development of a high altitude model isplanned in FY 2008.