Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-1A

Designing for Safety: the Free Flight ATM concept

Jacco Hoekstra (hoekstra@nlr.nl)

Ronald van Gent

Rob Ruigrok

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-2A

1997: Three sub-studies: CONCEPTUAL DESIGN

Tool: 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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-3A

Free Flight goals

Reduce Costs via user preferred routing– Horizontally

• direct to destination• optimum speed

– Vertically • optimum level• cruise climb

More capacity

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-4A

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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-5A

Traffic & Experiment Manager TMX

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-6A

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

Conceptual Design

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-7A

Conflict Detection & Resolution

Intruder’s protected

zone

Heading distance

Speed change

Avoidance vector

Minimum distance

Ownship

Intruder

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-8A

Airborne Separation subtasks

Monitoring traffic situation on display

Conflict detection

Conflict resolution

Inter-traffic R/T

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-9A

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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-10A

Conflict Detection & Resolution

Symbology based on resolution algorithm

Provides insight into resolution

Colour indicates urgency:Amber = 3 - 5 minRed = 0 - 3 min(time to loss of separation)

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-11A

Inter Traffic R/T

Call sign added to label of traffic symbol

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-12A

Navigation Display

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-13A

Topaz Safety Analysis

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

Airway

Airway

Route spacing

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-14A

TOPAZ : Ground vs. Airborne Separation

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-15A

TOPAZ : Airborne Separation

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-16A

Man-in-the-Loop experimentHypotheses

First explorative HF experiment, so probably:

Less than acceptable

Subjectively less safe

More workload

Goal: MMI problem areas

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-17A

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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-18A

Man-in-the-loop simulation

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-19A

Experimental Design

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

• 18 runs per crew

• air line pilots

• 2 days incl. half a dayof training

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-20A

Man-in-the-loop Simulation Configuration

AIRSIM

RFS

TMX

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-21A

Man-in-the-Loop experimentResults - Acceptability

0

10

20

30

40

50

60

70

80

90

100

su

bje

cti

ve

rati

ng

acce

pta

bilty

in

pe

rce

nta

ge

s

single

double

triple

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-22A

Man-in-the-Loop experimentResults- Subjective Safety

0

10

20

30

40

50

60

70

80

90

100

ATC muchsafer

ATC safer Same FF safer FF muchsafer

Su

bje

ctiv

e r

atin

gs

saf

ety

in p

erc

en

tag

es

set 1

set2

set3

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-23A

Man-in-the-Loop experimentResults

Subjective Workload

33.85 35.4228.76

0

20

40

60

80

100

120

140

first second third

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-24A

Task comparison Controlled vs. Free Flight

Fly

Navigate

Communicate with ATC

Fly

Navigate

Separation

Controlled Flight Free Flight

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-25A

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.

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-26A

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: =>Predictive ASAS

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-27A

1998 Student studies Avionics requirements

- navigation- ADS-B (bandwidth)- reliability=> today’s technology +ADS-B allows FF

Conflict geometries (TMX)- Wall scenario- Super conflicts- Shallow conflicts (hor. + vert.)=> tuning of CD&R

Performance and fuel/time aspects of conflict resolution- simulations Fokker 100 on TMX=> Vertical optimal, FF savings due direct routing high

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-28A

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)

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-29A

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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-30A

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

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-31A

Predictive ASAS

Don’t go indications:• Track• Vertical speed• Speed

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-32A

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!

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-33A

Plans for 1999

Further data analysis of 1998 experiment

Comprehensive report on overall studies 1997-1998

Human interaction experiment (?)

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-34A

Distributed vs. Centrally controlled systems

Chaos

Robustness

Capacity

Safety and certification

Challenging for analysis

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-35A

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 future…No change is also a risk!

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-36A

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