Designing for Safety: the Free Flight ATM concept

1
Designing for Safety the Free Flight ATM
concept

• Jacco Hoekstra (hoekstra_at_nlr.nl)
• Ronald van Gent
• Rob Ruigrok

2
1997 Three sub-studies

• CONCEPTUAL DESIGNTool Traffic Manager Off-line
  simulations
• Find a suitable base-line concept
• SAFETY ANALYSISTool TOPAZ (Traffic Organization
  and Perturbation AnalyZer)
• Compare safety of Airborne Separation with safety
  ATC
• MAN-IN-THE-LOOP EXPERIMENTTool Research Flight
  Simulator
• Validation of concept with Man-in-the-Loop
• Man Machine Interface Validation

3
Free Flight goals

• Reduce Costs via user preferred routing
• Horizontally
• direct to destination
• optimum speed
• Vertically
• optimum level
• cruise climb
• More capacity

4
Starting points

• No ATC
• Probe the limits for HF problems
• All aircraft fully equipped
• Linked via e.g. ADS-B
• EFIS-CDTI
• Full user preferred routing
• Direct routing
• Optimal cruise altitude

5
Traffic Experiment Manager TMX
6
Conceptual Design

• Resolution advisoriesSeveral concepts studied
• Altitude step
• Cross product of speed vectors
• Extended VFR rules (not implemented)
• Variations of TCAS manoeuvres
• Voltage potential
• Co-operative manoeuvring vs. priority
• Minimal bandwidth/HF no intent in Conflict
  Detection

7
Conflict Detection Resolution
8
Airborne Separation subtasks

• Monitoring traffic situation on display
• Conflict detection
• Conflict resolution
• Inter-traffic R/T

9
Monitoring traffic situation on display

• Symbology on Navigation display based on data
  available via ADS-B
• Track indicated with arrow shaped symbol instead
  of track line to avoid clutter
• Label text selectable with declutter switches

10
Conflict Detection Resolution

• Symbology based on resolution algorithm
• Provides insight into resolution
• Colour indicates urgencyAmber 3 - 5 minRed
  0 - 3 min(time to loss of separation)

11
Inter Traffic R/T

• Call sign added to label of traffic symbol

12
Navigation Display
13
Topaz Safety Analysis
Airway
Route spacing
Airway

• Two airways in opposite direction
• Independent variables route spacing,
  non-nominals
• Dependent Collision frequency
• ASAS equipped, airborne separation, good weather,
  no global ADS-B failure, independent transmitter
  receiver
• No monitoring modelled on ground air

14
TOPAZ Ground vs. Airborne Separation
15
TOPAZ Airborne Separation
16
Man-in-the-Loop experimentHypotheses

• First explorative HF experiment, so probably
• Less than acceptable
• Subjectively less safe
• More workload
• Goal MMI problem areas

17
Man Machine Interface

• Modifications to Navigation Display
• Traffic symbology
• Conflict detection
• Resolution Advisories
• Vertical Navigation Display
• Extra EFIS Control Panel functionality
• Modifications to Autopilot
• Execute combined
• Execute separate
• Aural alerts
• Dedicated blue light under glareshield

18
Man-in-the-loop simulation
19
Experimental Design

• 18 runs per crew
• air line pilots
• 2 days incl. half a dayof training

• Place of non-nominals in matrix changed between
  subject crews

20
Man-in-the-loop Simulation Configuration
RFS
AIRSIM
TMX
21
Man-in-the-Loop experimentResults -
Acceptability
22
Man-in-the-Loop experimentResults- Subjective
Safety
23
Man-in-the-Loop experimentResults
24
Task comparison Controlled vs. Free Flight
25
Conclusions 1997

• Free Flight concept as implemented is acceptable
  in cruise phase, even in higher than WE densities
• Workload in a future Free Flight scenario in
  cruise phase is not higher than in present day
  ATC scenario
• Free Flight concept is at least as safe as
  present day ATC
• None of the three sub-studies (off-line
  simulations, TOPAZ safety analysis,
  Man-in-the-Loop experiment) could refute the
  feasibility of an Airborne Separation Assurance
  concept for a future Free Flight environment.

26
Recommendations

• Fine tuning of conflict detection resolution
  based on remarks of pilots
• Intended Flight Level in label?
• Extra rule to prevent turning into short-term
  conflicts gtPredictive ASAS

27
1998 Student studies

• Avionics requirements- navigation- ADS-B
  (bandwidth)- reliabilitygt todays technology
  ADS-B allows FF
• Conflict geometries (TMX)- Wall scenario- Super
  conflicts- Shallow conflicts (hor. vert.)gt
  tuning of CDR
• Performance and fuel/time aspects of conflict
  resolution- simulations Fokker 100 on TMXgt
  Vertical optimal, FF savings due direct routing
  high

28
1998 Man-in-the-loop study

• Mixed equipage procedures- Free Flight Level
  (ASAS flies higher)- Protected airways
  (non-ASAS stay on airways)- Fully mixed
  (non-ASAS longer look-ahead time)
• Predictive ASAS- system developed on TMX-
  enhances situational awareness- new rule it is
  forbidden to turn into a short-term conflict
• Pilots controller in the loop- only in single
  and double density connected (triple too high
  for ATC)

29
Mixed equipage procedures

• Data analysis is in progress
• Preliminary results (impressions)- protected
  airways not feasible- FF able to cope with
  higher traffic density- co-operative/corrective
  action from airborne crew

30
Predictive ASAS

• Calculates which track, vertical speed and speed
  selections will result in a conflict within the
  look ahead time
• Predicts a conflict by the red/amber zone moving
  to the actual values
• Indications do not require pilot actions

31
Predictive ASAS

• Dont go indications
• Track
• Vertical speed
• Speed

32
Preliminary conclusions PASAS

• With predictive ASAS even conflict alerts could
  be avoided
• Enhances situational awareness
• Might provide solution without use of intent
  information for Free Flight!

33
Plans for 1999

• Further data analysis of 1998 experiment
• Comprehensive report on overall studies 1997-1998
• Human interaction experiment (?)

34
Distributed vs. Centrally controlled systems

• Chaos
• Robustness
• Capacity
• Safety and certification
• Challenging for analysis

35
Conclusion

• Free Flight promises to be very powerful- fuel
  time savings- higher capacity- safer (more
  robust, also technology dep.)- no reliance on
  ground aids and their reliability- individual
  self-optimisation
• Needs further research!!!
• FF will happen now or in the futureNo change
  is also a risk!

36
NLR Free Flight Web site http//www.nlr.nl/public/
hosted-sites/freeflight or via NLR home page
http//www.nlr.nl and select hosted sites