ABSOLUTE FLOW CONTROL

1
ABSOLUTE FLOW CONTROL
AVTECH Sweden AB
Linköpings University
2
Jon H. Ertzgaard, AVTECH Sweden AB RNoAF, USAF
ETPS Saab Chief Test Pilot and Project Test
Manager -J35F Draken-AJ37 Viggen, Saab 340, Saab
2000, man. guided missiles. J39 Gripen Flight
Control System CAA Chief Test Pilot Saab 340
Certif. SAS Line Capt., Instructor, Project
Pilot, Headed the AI/Airline A340/A320
Cockpit-Systems Integration Group Cosultant to
NASA (Ames), Fokker etc. Saab Friction
Tester Håkan Andersson, University of
Linköping Master of Science, Comunication and
transportation systems
3
AIR TRAFFIC CONTROL
- problem solving of a continuously
selfgenerating chaotic situation DENSITY
VARIATIONS ATC INTERVENTION STRATEGIC
planning TACTICAL intervention SLOT TIMES
4
SEPARATION
VIOLATION
CONFLICT
WASTE
None Metered Flow
Flow
Min. separation
Time
5
Metered Flow
None-metered Flow
Inbound Flow
ATC Approach Control METERING
Conflict
RWY
Minimum landing separation
Maximum approach flow
Time
En-route
OLD
Final approach-
Land
AOC -X
6
DISTANCE vs TIME
8 NM / minute
?
NM / minute
2,5 NM / minute
Distance compression
7
Metered Flow
Inbound Flow
Fine METERING
ATM Flow planning METERING
RWY
Minimum landing separation
Maximum approach flow
Time
AOC
NEW
Final approach-
Land
En-route
8
METERED FLOW 4-D NAV Planning 4-D NAV
Execution Optimum flight (Free Flight)
9
Routes Flown for Trials

• 33 RTA trial flights conducted by Smiths
  Aerospace with SAS.
• Swedish CAA provided undisturbed priority
  servicing.
• 17 different flight crews.
• Smiths Aerospace test conductor in jumpseat with
  SONY Digital-8 camcorder.

10
TRAIL Time Referenced Traffic In Line
11
TRAIL

• Accurate Time Separation based on Distance
  and Ground Speed only
• Tactical Sequencing and Separation tool
• ATC defined Flight Crew executed
• Requires accurate positioning
• Accuracy equal to or better than 4-D Nav.

12
TRAIL

• Mixed equipage
• Failure cases backup
• Wind information / Speed Profile
• Parallel runways

13
CONTROL METHODS

• OLD
• Distance control
• Information transfer lag
• Accuracy

Sep. min
Number of touch downs
Old
Touchdown separation (time)
14
OBJECTIVE
Investigate methods to increase air traffic flow
(runway throughput) up to physical or regulatory
limits reduce waste of airspace increased
flow (throughput)
15
OBJECTIVE
Understand Air Traffic Flow and define Control
Mechanisms to - STABILISE Flow - MAXIMISE
Flow APPROACH LANDING (ARRIVAL RATE /
RUNWAY THROUGHPUT)
16
OBJECTIVE
Improved understanding of - Flow
characteristics - Flow disturbances and
propagation /damping - Flow control
1
2
17
Maximum advantage with minimum changes
to procedures and infrastructure
18
Traffic flow characteristics

• Compressibility
• Density
• Aircraft performance
• Pilot/Controller performance
• 3-dimensional flow

19
Flow Density Relation to Air-traffic

• Method
• Analogy from Road-traffic R/D
• Assumed as 1-dimensional flow
• Focus on final approach (traffic stream)
• Definition of
• Critical factors
• Max and optimal density

20
ROAD TRAFFIC FLOW

• Old problem (1950)
• Flow models
• Similarities with Air traffic flow
• Precision of a second
• Compressible
• Differences
• Need of speed
• Leakages of flow

21
Flow - density Final approach Traffic stream

• Kopt gt qmax
• Kmax sep. min

kopt
kmax
Vmax
qmax
Vmin
Free flow
Resulting Flow, q (veh/hr)
Forced flow
Over saturated flow
Planned Density, k (veh/mi)
22
Touch down distribution
Sep. min
Number of touch downs
Present system
Touch down separation (time)
23
Present ATC control loop
Pilot
Aircraft
Radar
Controller
24
Improved control loop
Pilot
Aircraft
F(t)
High accuracy A/C position ADS-B
REDUCED TRANSFER LAG
Controller
F(t) Control law
25
Automatic control loop
Pilot
Aircraft
POSSIBLE????
F(t)
GNSS
Controller
F(t) Control law
26
TRAIL CONTROL LAW

• Requires relative position and Ground Speed
• PDI-Controller
• Input Time Error
• Output Acceleration

Air Air Information
Time error
Required time
Relative Position
27
String control

Absolute reference control



28
Example

• Conditions
• String control
• Speed adjustment
• PDI-Controller
• 1Hz update frequency
• Equal aircraft performance
• Stable string
• Final approach

29
Speed profile
GS (m/s)
113
85
67
1 NM
19 NM
Distance flown from start of run
30
Speed Distance
31
Time error time
32
RESULTS

• Flow Control
• Stable
• High precision (milliseconds)
• Required developments
• Phase shifted speed profile
• Information transfer lag
• Gross control

33
FINDINGS
TRAIL separation Control accuracy measured in
meters and fractions of a second TRAIL
separation that approach legal and physical
limits (ROT, WING VORTEX)
34
FINDINGS

• AIRBORNE
• Systems available now (4-D Nav.) or soon (TRAIL)
• Compatible procedures
• GROUND
• Technical Systems modifications simple !
• - Procedures and responsibilities ???

35
Factors That Affects Flow

• Controllers precision and authority
• Disturbancese, For example Mix of aircraft
• Environmental Conditions
• Navigation accuracy
• Buffer Time Track

36
REQUIRED STUDY
Metered vs Unmetered Flow
Planning
Negotiation/Renegotiation
Sequencing
Ground Air
TRAIL vs 4-D
Execution
Old FMS, DME/DME New FMS, GNSS Mixed
equipage Accuracy and stability
37
CONTROL POWER
Track adjustment - gross control
Speed adjustment - fine control
IAS
38
REQUIRED STUDY
TRAIL
Speed Correction Authority
Track Correction Control Law
Robustness
Update rate (stability) Information Transfer Lag
(accuracy) Disturbance Mixed performance
39
CONSORTIUM
AVTECH - LIU
40
CONCEPT
STATEGIC PLANNING based on
4-D navigation information
STRATEGIC PLANNING based on 4-D navigation
4-D navigation or transition to TRAIL
OPTIMUM FLIGHT based on 4-D navigation
PLANNING AND EXECUTING A METERED FLOW
41
ATS
ATC STRATEGIC planning TACTICAL
intervention
ATM STRATEGIC planning TACTICAL
intervention
42

• 4-D NAV
• Position determination
• Silos/Railroad tracks
• FMS
• DME/DME
• GNSS
• Time

43
4-D NAV Requires common time
base Sequencing -Strategic Planning -Tactical
Intervention
44
RTA Time-Control WindowControl Power
7 Loss
3 Gain
45
Example of Modeled vs. Actual Descent Winds
46
- Present Air Traffic Management is a series of
disconnected events conspiring to prevent the
efficient conduct of flight -