This document discusses the application of the ALIAS methodology to analyze the ACAS X system. It describes getting stakeholder involvement, selecting scenarios to analyze, legal feedback on different automation levels, and conclusions. The legal analysis found procedures must be clear and decisions backed by study to improve safety and address liability issues. It was educational but a legal case may not be needed for every project; greater liability awareness and a LOAT-based guide would help address systemic issues.

1. ACAS X test application
Garfield Dean (EUROCONTROL)
Focal point for ALIAS ACAS X application
ACAS X intro

2. User Experience
 Step by step through the ALIAS methodology
 Was it worth it?
 What next?
ACAS X intro Page 2

3. Getting Started
 Important to get a good user team
 Who know the technology,
 Who can understand the ALIAS method.
 Indeed the case with ACAS X – however low involvement from
ANSPs, industry and certification/ regulation.
 Describing the system
 Simple task for well defined systems
 However, some documents unavailable for developing systems
 Level Of Automation Taxonomy (LOAT)
 Seemed straightforward to use
ACAS X intro Page 3

4. Selecting cases
 Selecting scenarios
 Similar to safety analysis
 Was not systematic over all risks
 Only cases that were of interest both legally and to ACAS X
 In retrospect chose cases that had the widest range of LOAT
levels
ACAS X intro Page 4

5. Legal Feedback
 Concentrated on Scenario 4 – ADS-B only aircraft
 Considered 4 very different automation levels
 Procedures are very unclear in two middle automation levels
but may still improve safety
 Potential conflict between safety and liability.
 Hierarchical breakdown of liability was intuitive and
informative
ACAS X intro Page 5

6. Was it worth it?
 An education on the Legal system
 Liability outcome can appear random from a technical
viewpoint.
 Barcelona court of appeal
 Reinforced the need for some good practices
 Clear, comprehensive procedure design
 Decisions backed up by study
 Legal measures only push risk around
between actors. They don’t improve safety
ACAS X intro Page 6

7. What next?
 Legal case for every project?
 Please no!
 Greater liability awareness in projects
 Perhaps a guide to liability implications based on LOAT
 Talks to management / project managers
 Address systemic issues
 Liability can limit when it is economic to build a sound safety system
 How to handle probability when the outcome before a court is an
accident occurred.
ACAS X intro Page 7