1. NOSS: The Methodology and Early Findings
Chris Henry
The University of Texas Human Factors Research Project
The University of Texas at Austin
UT Human Factors Research Project © Copyright

2. The University’s Role Member of the ICAO NOSS Study Group
Jointly conducted the first two trials of the NOSS methodology with Airservices Australia and Airways New Zealand.

3. NOSS Operating Characteristics
Over-the-shoulder observations during normal shifts
Joint Management/Union sponsorship
Voluntary participation
De-identified, confidential, and non-disciplinary data collection
Specifically designed form for collection of data
Trained and calibrated observers
Trusted data collection sites
Data cleaning process
Targets for safety enhancement
Feedback results to the controllers

4. Threats
Threat: An event or error that occurs outside the influence of the controller, but which requires their attention and management if safety margins are to be maintained.
Air Navigation Service Provider (Internal) Threats
Air Traffic Control – Pilot Interaction Threats
Environmental Threats

5. Threats Threat Categories
Air Navigation Service Provider (Internal) Threats
Airborne Threats
Environmental Threats
Examples
Errors by other controllers
Similar call signs
Adverse weather
Unserviceable equipment
Language difficulty
Airspace design
Procedures
A/C flying unassigned heading
Restricted Airspace
Coordination issue
Pilot not responding to call
Traffic mix
Computer malfunction
Other pilot errors
Turbulence

6. Errors
Error: An observed deviation from organizational expectations or controller intentions
Communication Errors
Procedural Errors
Equipment / Automation Errors
Traffic Handling Errors

7. Errors Error Categories Communication Procedural Equipment / Computer
Traffic Handling
Examples
Phraseology
Readback / Hearback
error
Missed call
Coordination error
Checklist
Briefing error
Aircraft transfer
Flight progress strip error
Did not check RWY prior to issuing TO clearance
AC label inaccurate info
Communication system manipulation
Radar screen range selection
Late decent
Incorrect clearance instruction
No altitude instruction

8. Undesired States Controller Console Setup US’s Traffic State US’s
Inaccurate representation of traffic
Traffic situation not being monitored
Incomplete handover
Traffic State US’s
Separation not assured
RWY/TXY not verified to be clear for progress

9. NOSS Trial Data NOSS trials LOSA archive 5.7 3.7 2.6 0.6 0.5 88% 63%
Threats per observation
5.7
3.7
Errors per observation
2.6
Undesired States per observation
0.6
0.5
Percentage of observations with an internal threat
88%
63%
Percentage of observations with pilot/ATC interaction threats
87%
54%
Percentage of observations with environmental (common) threats
78%
75%

10. Preliminary Findings
Greater threat prevalence of internal and ATC/pilot interactions when compared to LOSA
A few pilot – ATC interaction issues
Similar call signs
Readback / phraseology issues

11. Methodological Challenges
Will it work in the various ATC environments?
Focus on positions
Concerns
Observability: A similar number of observable errors are seen in NOSS and LOSA
Lack of proceduralization / standardization: There may be reason to compare organizations with different procedures

12. What’s Next? NOSS & LOSA: What can each add to the other?
Reliability and validity studies in conjunction with FAA
NAV CANADA NOSS area/terminal trial
Airservices Australia tower trial
Fully operational NOSS in 2006? Airservices?