Sector Complexity and safety Dr. Arnab Majumdar 26 OCTOBER, 2006
Plan Motivation Previous studies Controller interview methodology Tokyo ACC example Taxonomy Ratings Interactions Further research
Why a bottom up approach? Safety and sector design Traditional sector design - traffic flows - manage workload What factors affect controller workload? - controller interview data Taxonomy Impact on airspace design principles
What factors affect workload? SOURCE FA CTOR S MEDI ATING FACTOR S RE SULT QUALIT Y OF EQUIP MEN T ATC COMPLEXITY: AIR TRAFFIC PATTERN AND SEC TOR CHARAC TERISTICS INDIVID UAL DIFFE RENC E CON TROL LER WORKLOAD CON TROL LER COGNI TIVE STRATEGIES FACTORS AFFE CTING CONTROLLER W ORKL OAD Source : Mo gford et al. (1995), p age 5
Methodology
What factors affect workload? Interviews conducted on: Factors affecting controller workload How factors affect workload
Factors considered Traffic Mix Speed differential Entry and exit points. Number of surrounding sectors. Number of routes. Intersection points. Number of navaids. Number of Flight Levels. Sector geometry. Military airspace Bad Weather Japan specific
Which ACCs? Europe Maastricht Geneva Zurich CANAC Lisbon Dublin Shannon Vienna Copenhagen Oslo Malmo Asia Mumbai Delhi Kolkata Chennai Singapore Hong Kong Kuala Lumpur Tokyo Fukuoka
Taxonomy categories Traffic Measures Traffic Mix Measures Traffic Speed Mix Entry and exit point Measures Routes Measures Intersection points, reporting points Flight Levels Neighbouring sectors Restricted area, Military airspace, Special area Sector Geometry Weather Others
Japan Traffic
Japan Traffic Trends TOTAL TRAFFIC Japan 1992-2004 2500000 2000000 Aircraft 1500000 1000000 500000 0 1992 1994 1996 1998 2000 2002 2004 Year ACC Traffic in Japan 1992-2004 Aircraft 1200000 1000000 800000 600000 400000 200000 0 SAPPORO NAHA FUKUOKA TOKYO 1992 1994 1996 1998 2000 2002 2004 Year
Japan Traffic Trends New Chitose Domestic Traffic Flow Fukuoka Osaka Narita Haneda Kansai Chubu
International Traffic Flow ANCHORAGE FIR 50N International air traffic flow Anchorage East coast of USA Europe/Russia SAPPORO ACC Korea INCHEON FIR TOKYO ACC West coast of 40N USA China FUKUOKA ACC ATM CENTER NAHA ACC FUKUOKA FIR Hawaii 30N OAKLAND FIR South East Asia MANILA FIR Guam/Australia 140E 160E 20N
Tokyo ACC Complexity
Tokyo ACC Traffic Profiles Ascends & descends Descends > Ascends > Cruise Unexpected movements: - weather - emergency - not predicted
Tokyo ACC Speed Slow followed by fast Descends & Ascends Focus of attention on slow aircraft Three different regions: West: (descends & climbs) + different airline + ac type East: Near military airspace so restricted manoeuvres for speed difference North: Near major TMAS so apply procedures in ACC Airline dependent aircraft performance Pilot familiarity with Japanese conditions VFR mix in good weather Non-RVSM ac in RVSM airspace
Tokyo ACC Entry and exit points More entry points more workload Exit points important especially when to approach areas Location important Keep entry and exit points well separated If entry and exit points less than 10nm separated then workload problems
Tokyo ACC Crossing routes high workload situations: More crossing points 3 crossing points in North Sector near each other Crossing points with Descends & Ascends Short Route vs.. Long Route Long route with deviation Short route with flights changing levels If climbs and descends: Route length does not matter much!
Tokyo ACC Aircraft converge to a point: Monitor separation Need to manage this in time RNAV Routes Dispersed crossing points in sector Short route with flights changing levels Sector boundary routes: High workload if deviation
Tokyo ACC Narrow angle of converge: More workload; Additional problem with convergence point close to sector boundary. Bi-directional routes: Ascends & descends Nuisance RAs on TCAS.
Tokyo ACC RVSM indicates that more FLs better for managing controller workload. BUT: Congestion intensified Many ac at the same time in airspace request same level; Problem near to approach areas of Narita and Haneda.
Tokyo ACC Neighbouring sectors Vertical sectors established by coordination from Upper sectors to lower adjacent sectors pose many problems - so abandoned. Successful in Sapporo where traffic is less. Major impact of flow control in neighbouring countries: China requests larger separation This flows to Incheon and leads downstream to Tokyo which has to hold traffic Incheon ACC small and much military aircraft - won t ccept aircraft Similarly with Hong Kong-Tapei Tapei-Naha-Fukuoka-Tokyo.
Tokyo ACC Sector shape and size Should be divided by traffic flow Some large sectors Pose problems on radar range Fukuoka: Narrow sectors are major problem
Tokyo ACC Military airspace Major problem as US base close Haneda departures affected Much coordination required Cannot enter naval airspace No FUA Bad weather problem Can use JDF areas
Tokyo ACC Bad weather Not just CBs but also typhoons Much workload after bad weather over Aircraft departures and holding Two other phenomena Runway closed due to earthquake Snow forces runway closure Consequences En-route holds Unidirection routes to bi-directional
Tokyo ACC Other issues I Language barrier a major problem Works in 2 ways Chinese pilots to Japanese controllers American pilots to Japanese controllers Use of non-technical terms Familiarity with Japanese airspace important
Tokyo ACC Other issues II Japanese culture Shared mental model No need for communications? Loss of separations Age issues? Older controller community
Taxonomy
Taxonomy categories Traffic Measures Traffic Mix Measures Traffic Speed Mix Entry and exit point Measures Routes Measures Intersection points, reporting points Flight Levels Neighbouring sectors Restricted area, Military airspace, Special area Sector Geometry Weather Others
Ratings ACC Variable Average Rating Mix of descends and ascends 3.00 Pilot compliance with instructions 2.83 Range and quality of RT communications 2.83 Maximum number of aircraft instantaneously the sector 2.67 Number of aircraft entering the sector 2.50 Frequency congestion measure 2.50 Clustering of aircraft in sector 2.50 Mix of slow and fast moving aircraft 2.50 Number of intersecting routes in the sector 2.50 Number of intersecting bidirectional routes 2.50 Location of bad weather regions in sector 2.50 Time of peak traffic period, e.g. circadian rhythms 2.50
Combinations of Variables Variable One Mix of descends and ascends Number of intersection points in a sector Number of intersection points in a sector Small Sector volume Crossing Bidirectional routes Large Sector volume Number of Entry Points (weighted by flights) Small Sector volume Small Sector volume Long Route length Long Route length Long Route length Route close to the sector boundary Mix of descends and ascends Mix of descends and ascends Mix of descends and ascends Variable Two Mix of slow and fast moving aircraft Angle of crossing at intersection point Geographical location of intersection points in the sector Volume of airspace restricted in the sector Mix of descends and ascends Geographically disparate intersection points in the sector Geographical location of intersection points in the sector Many entry and exit points Mix of descends and ascends Mix of descends and ascends Crossing points Route close to the sector boundary Number of crossing points Directions of flow Number of intersection points in a sector Number of Entry Points (weighted by flights)
Combinations of Variables - Example
Levels of complexity - Example Level Level 1 Level 2 Level 3 Level 1 Level 1 Complexity Factor 1 Complexity Factor 2 Complexity Factor 3 Complexity Factor 4 Complexity Factor 5 Mix of descends and ascends Mix of descends and ascends Mix of descends and ascends Mix of descends and ascends Mix of descends and ascends Long Route length Long Route length Long Route length Long Route length Route close to t he sector boundary Route close to t he sector boundary Route close to t he sector boundary Crossing points Crossing points Angle of Crossing
Further Research