1. HCI in Safety-Critical Applications: ATC Systems Aslan Neishaboori

2. Background ● Introduced after WWII by U.S. Military ● Three evolutionary phases: ● Voice communication and time estimation ● Radar was added in late 1950's ● Introduction of computers as aids to controllers

3. Background (cont') ● Current system is extremely, but not completely safe ● Levels of air traffic is increasing rapidly ● With this increase rate the number of accidents will increase substantially ● Either limit number of flights, or increase saftey

5. Air Traffic ● FlightAware.comFlightAware.com ● LAXLAX

6. Air Traffic Control ● Terminal or airport control ● Traffic on the airport surface ● Airborne traffic within immediate environment ● En-route or area control ● Airborne Traffic between the terminals

7. En-route Control ● Hight altitude traffic control between towers ● Maintains: ● Minimum separation requirements ● Optimal route for specific aircraft ● Smooth traffic flow

8. En-route Control (Cont') ● Minimum separation requirements: ● Vertical ● Horizontal ● Generally between 2-5 nautical miles

9. En-route Control (Cont') ● Optimal route for specific aircraft ● Influenced by fuel efficiency ● Depends on altitude ● Based on type of aircraft and weight ● Smooth traffic flow

10. Sectors / types of control ● The air space is divided into sectors ● Strategic ● Tactical (Radar)

11. Controller Types ● Strategic: ● receives & manages incoming traffic ● coordinates with controllers at other sectors ● multiple aircraft ● spans longer periods of time ● Tactical (Radar): ● negotiates with pilots ● minimum separation of aricraft ● current moment

12. A typical controller Team ● One chief controller ● Two radar controller ● Two assistants with military rankings

13. Two Views of Air Traffic ● Radar: ● Tracks current position of aircraft ● Paper strips (Flight progress strips): ● Organize the traffic ● Plan strategies ● Record key decisions

14. Paper Strips ● Each strip represents a flight

15. Paper Strips (cont'd) ● Very flexible ● Easy to use ● Quick way to annotate a flight ● Don't break down ● Serve as visual and tactile memory

16. Paper Strip Boards ● Used as a representation of all flights in sector ● Layout of each strip with respect to others is important ● aircraft in conflict are put next to each other ● Reduces controllers mental load by allowing them to retain only important information ● Support cooperative work

18. The Problem With Paper Strips ● Paper strips belong to another era ● Require strong effort to integrate information on them and information on radar screen ● Task automation is impossible

19. Strip-less ATC ● Many of the manual and repetitive tasks can be delegated from controllers to computers ● Automatic conflict detection ● Automatic sequence planning ● Decrease the controllers work load ● Potentially increase the safety of the system

20. Current Trend in ATC Systems ● Billions of Dollars have been spent by FAA ● 1.6 Billion USD for ATOP (Advanced Technologies and Oceanic Procedures) ● To automate tracking over Atlantic, Pacific and Arctic Oceans (will be completed by 2012) ● Majority of ATCs are still not fully automated ● According to FAA manual, paper strips are still as pervasive as before

21. Failed Attempts ● Paper less ATCs in two EuroControl Centers ● Only in small centers ● Simplest traffic sectors ● Electronic strips were completely ignored ● Proliferation of adhesive notes on desk & radar ● potential safety consequences ● non standard procedures

24. Irreplaceable Paper Strips? ● Intangible factors ● Touching the paper strips creates a sense of “owning” the aircraft ● The Act of writing is another important factor ● Difficult to reproduce by electronic versions ● Poor interface design ● Automatically arranging the electronic strips

25. Irreplaceable Paper Strips? (Cont') ● Just one routine for all situations ● low and high traffic ● calm traffic and multiple conflict situations ● if task becomes more boring in calm situations, the controllers might stop paying attention

26. Active Control vs Passive Monitoring ● Task allocation between controller and computer ● Active control ● Computer aids support the controller ● Passive monitoring ● Intervention in only rare but dangerous situations ● Out-of-the-loop performance issues

27. Sociology vs. engineering ● Software engineering: ● synthesis and designing ● hiding the details through abstraction ● Must make judgments about what is significant ● Has to be quick ● Sociology (Ethnographic researches) ● Analytic (looking for the details) ● Not judgemental about social situations ● Requires a long period of data collection and research

28. Conclusion ● Design of safety-critical systems differs from other interactive systems ● Improving productivity is important but safety remains the overriding concern ● Increasing the former at the expense of the latter is simply not acceptable ● Any replacement software needs to take the users' point of view into consideration ● Users can resist and/or ignore the replacement

29. No Questions Thank you