2nd ENRI International Workshop on ATM/CNS[EN-103] Development of Trajectory
Prediction Model
11 November 2010

Electronic Navigation Research Institute
Y. Fukuda, M. Shirakawa, A. SenoguchiContents
BackgroundMethod of Trajectory PredictionComparison of Prediction
 Weather Forecast
 Aircraft Speed ModelAnalysis of Error Factors
SummaryTrajectory Based Operation
Continuous Climb Operation

10:20

10:00
10:40
Departure Airport
Data link

4D Trajectory
Continuous DescentOperation

11:00

Controlled Time of Arrival
Destination Airport
 Trajectory：A description of the movement of an aircraft, both inthe air and on the ground, including position, time and, at least via
calculation, speed and acceleration.（ICAO Doc 9854)

Future VisionTrajectory based operation is a key
operational concept in future vision.
 Global ATM operational concept (ICAO) NextGen : Next Generation Air Transportation

System) (USA) SESAR : Single European Sky ATM Research(EUROCONTROL) CARATS : Collaborative Actions for Renovation ofAir Traffic Systems (Japan Civil Aviation Bureau)
 ENRI long term research vision

Technology Development
Optimization and control of one aircraft Managed by FMS（Flight Management System）
 Flight Time, Fuel: RNAV, RNP

Optimization and control of all aircraft Ground based trajectory prediction and control

system is required for all aircraft.
 Conflict Detection, CTA (Controlled Time ofArrival) Assignment, Trajectory Coordination
RNAV: Area Navigation
RNP: Required Navigation PerformanceActual Trajectory Examples
Flight pathextension neardestination airport
because of traffic
congestion.

37TokyoLatitude（Deg）

Fukuoka
3533100 NM
31129

131

133

135

137

139

141

137

139

141

Altitude（ft）

Longitude（Deg）
40000
30000
20000
10000
0129

131

133

135
Longitude（Deg）

Blue：
Tokyo -> Fukuoka
Red：Fukuoka -> Tokyo
Light Blue:
Flight Plan RouteTrajectory Prediction Model
Airline Operation
ModelAltitude
SpeedWeight

Energy Condition(T  D) VTAS  mg

Navigation Database
Lat. Lon. of Waypoints
RouteDept./Arv. RouteAircraft
Performance Data

Trajectory
Predictor

Vdh mVTAS TAS
dtdt

Weather
Forecast

Surveillance Data
Actual Trajectory

Flight Envelope
Aerodynamics（Wind, Temp.）

4D Trajectory

Evaluation, Prediction Error Analysis

Flight Time Calculation
Distance S
Point P
Small Segment s
Point O

Ground Speed VGND (s)Flight time from O to P
＝Sum of small segment flighttime (s /VGND(s))

S10

VGND ( s )Tp  ds

Prediction Model Total Energy Model （Point-Mass Model）

LiftThrust UncertaintiesGravity

 Aircraft type
 Flight condition
 Pilot operation
 ATC instructions
 Meteorological conditions

DragType
AttitudeConfiguration
VTASdh(T  D) VTAS  mg
 mVTAS
dt
dt

Prediction Method
 Speed estimation is important for time prediction.
Calibrated Air
Speed (CAS)

True Air
Speed (TAS)Air Density

600

Speed （kt)500
400
300200

TAS100

CAS0010,000 20,000 30,000 40,000 50,000
Altitude （ｆｔ)GroundSpeed (GS)+WindGround Speed Calculation
Ground Speed =True Air Speed+ WindTrue North

fWWindTrue Air Speed

W
Track Angle

fTVTASf D Drift Angle
V GND
Ground Speed

Prediction Data Aircraft Performance Model BADA (Base of Aircraft Data) of EUROCONTROL Meteorological Forecast
 JMA (Japan Meteorological Agency), GSM, MSM
36.5

GSM

MSM （GPV)

Area

Global scale

Meso scale

Area

Global EarthJapan

Update cycle

6 hour3 hourGrid

0.5 deg

0.125/0.1 deg

Vertical

1,000hPa (364ft) – 100hPa (53,083ft), 12 layer

GSM
MSM
36.0
Latitude（deg）

Model Name

HANEDA

NARITA

35.5

35.0

34.5
139.0

139.5 140.0 140.5
Longitude（deg）

141.0

Comparison Methods
WeatherForecast
Aircraft Speed

Measured data by aircraftPredicted data by interpolationof numerical forecast (MSM)
Measured data by aircraftPredicted data with BADA
speed model

Comparison of Climb
Wind Speed
WS (kt)40,00035,00030,00025,00020,00015,00010,000
5,000
0
11:30

11:35

11:40 11:45
Time (hh:mm）

11:50

11:55

3530
2520
15
1050
11:30

350
300
250
200
150
10050
0
11:30

GS(kt)

CASCAS(kt)Altitude （ｆｔ）Altitude

Measured
Predicted
11:35

11:40 11:45
Time (hh:mm）

11:50

11:55

600
500
400
300
200
100
011:30Measured
Predicted
11:35

11:40
11:45
Time (hh:mm）

11:50

11:55

Ground Speed

Measured
Predicted
11:35

11:40
11:45
Time (hh:mm）

11:50

11:55

Comparison of DescentWind Speed
WS (kt)40,00035,00030,00025,00020,00015,00010,000
5,000
0
12:20

12:25

12:30 12:35
Time (hh:mm）

12:40

12:45

3530
25
20
15
10
50
12:20

CAS350
300
250
200
150
100
50
012:20Measured
Predicted
12:25

12:30
12:35
Time (hh:mm）

12:40

12:45Ground Speed
600
500

GS (kt)CAS (kt)

Altitude （ｆｔ）

AltitudeMeasured
Predicted
12:25

12:30
12:35
Time (hh:mm）

400
300
200
100

12:40

12:45

012:20Measured
Predicted
12:25

12:30 12:35
Time (hh:mm）

12:40

12:45

Error Factors of Ground Speed
Ground SpeeddVGND Wind Speed
VGND
WdW VGND

 VTASWind Direction

VGND
fW

dVTAS dfW

VGND
fTdfT

Track Angle
True Air Speed（Mach、CAS、Temperature）
 Partial Derivative Coefficient：
Degree of Influence of Each Factor
 Total Derivative of Factor： Error of Each Factor

Prediction Error in Climb
GS Error Distribution

Error Factor
30

The number of ACError Factor (kt)40
200-20-40WS
Temp-60-80
11:30

WDCAS

25
20
15
10
50

11:35

11:40
11:45
Time (hh:mm)

11:50

11:55

Average GS Error : -5.3 kt-80 -60 -40 -20 020GS Error (kt)

84 aircraft

4060

80

Prediction Error in Descent
GS Error Distribution

4030

20

250-20-40
WSTemp-60-80
12:20

12:25

12:30
12:35
Time (hh:mm)

WDCAS
12:40

12:45

Average GS Error : 0.44 kt

The number of AC

Error Factor (kt)Error Factor
20151050-80 -60 -40 -20 020GS Error (kt)

85 aircraft

406080Summary
ENRI is developing the trajectory prediction
model for trajectory based operation.
Error factors due to the aircraft speed
model and error factors due to weather
forecasts were analyzed for Ground Speed(GS) prediction.
Aircraft speed model error was larger thanweather forecast error in most cases.
Measured GS is smaller than predicted GS.

Future WorksClimb and descent rate analysis.
Weather forecast error detailed analysis.
Algorithm development to modify
trajectory to resolve conflicts and meet
CTA (Controlled Time of Arrival).