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Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
Operational Errors - Interaction with TCAS RAs
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Operational Errors - Interaction with TCAS RAs

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  • 1. 7th ATM R&D Seminar – Barcelona (Spain) – July 2-5, 2007 Kevin M. Corker, PhD Professor, San Jose State University & Jose L Garcia-Chico ATC Research Analyst Titan Industries An analysis of Operational Errors: An Analysis of Operational Errors and the interaction with with TCAS Interaction TCAS July 2-5 , 2007
  • 2. Agenda Problem Statement - Motivation 1 TCAS system and operators’ behaviour 2 Methods 3 Results 4 Conclusions 5 Slide 2 July 2-5 , 2007
  • 3. Problem Statement • Operational Error (OE) rate has been increasing through 2003 and reaching a plateau in the US airspace. The absolute number of OEs is still increasing. OE rate per 100,000 facility activities 0.8 0.78 0.78 0.77 0.74 0.69 1211 0.66 1216 1506 0.6 0.6 0.56 0.53 0.52 0.52 0.51 FAA (2006, April). Administrator’s Fact 0.4 Book. Washington, DC: Department of 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Transportation. • Specific Interest: recent accidents/incidents involving TCAS • For Example • Yaizu (2001), TCAS involved in both a/c. No fatalities • Uberlingen (2002), TCAS involved in both a/c. 71 fatalities Slide 3 July 2-5 , 2007
  • 4. Motivation & Ongoing Study • Classify operational errors and contextual factors in ATC in search of trends and consistency in the classification. • Assumption: classification of errors provides understanding of work performance and organizational/operational context. • Focus on presence of TCAS RA in evolution of the operational error • TCAS is an effective safety system, with caveats… It might disrupt the controller’s SA (Brooker, 2004; Wickens et al, 1998) Amplified by the fact that changes FL (vertical resolution) are only provided as number in data block) It might create inconsistent pilot and controller responses (Rome et al., 2006, Wickens et al, 1998) Intention: Understand procedural and informational context of OEs co- occurring with TCAS RAs. Slide 4 July 2-5 , 2007
  • 5. TCAS – expected behavior • For TCAS to work as designed, immediate and accurate crew response to TCAS advisories (action within 5 sec.) is essential. • Regulation of TCAS: operational procedures and practices (FAA AC 120-55B) Pilots: • Should follow TCAS RA, unless doing so would jeopardize the safe of operation. (Required response within 5 sec of RA display) • During an RA, do not maneuver contrary to the RA based solely upon ATC instructions. • S/he has to report any deviation from ATC clearance, as soon as practicable after responding to the RA, and resume previous clearance after “clear of conflict” Controllers: • Will not knowingly issue instructions that are contrary to RA guidance when they are aware that a TCAS maneuver is in progress. Slide 5 July 2-5 , 2007
  • 6. TCAS events timeline (“desired”) Pilot notifies Return to clearance Pilot follows RA & deviates from clearance Clear of conflict Pilot notifies ATC of deviation RA ATC aware deviation Timeline ATC SA Impaired Window to receive ATC Window to receive ATC clearance in opposition to RA clearance in opposition to RA with controller aware of RA without controller aware of RA Controller provides traffic info, If workload permits Controller is not responsible for separation Adapted from: Brooker, P. (2004). Thinking about downlink of resolution advisories from airborne collision avoidance systems. Human Factors and Aerospace Safety 4 (1), 49- 65. Slide 6 July 2-5 , 2007
  • 7. Other TCAS research: Operator behavior during TCAS • TCAS in simulation settings (Rome et al., 2006) • Variability and deficiencies in pilot communications • TCAS RA maneuvers increased stress • Controller cleared vertical deviations during RA maneuvers (4 out 32). • Research on RA downlink (Brooker, 2004; Eurocontrol, 2003b, 2004) • Controllers found it beneficial: – Improve SA and – avoid contradictory ATC clearances. • Problematic issues: – overload of information, – pilot compliance, – change in responsibilities, – procedures, – liability. Slide 7 July 2-5 , 2007
  • 8. Methods • Exploratory Study: mapping relationships in the data. Analysis of errors based on preliminary and final Air Traffic Controller Reports • Excluded: Surface and Oceanic Errors • Two studies/datasets: Taxonomic Study: classification of OE initial incident reports (Jan-Jun 04 period: 480 OE reports) • Classification of OEs based on FAA classification schema. • Relevance of coordination, training, proximity, time on position. Focused Study: OEs with presence of TCAS RAs. Final reports (Jan-Jun 2004 & 2005: 62 reports) • Use of same classification. • Characterization of the TCAS RA events. Human response. Slide 8 July 2-5 , 2007
  • 9. Slide 9 Fa il C on 0 10 20 30 40 50 60 70 80 90 C v er on gi D ng es trol 28 c ce 84 nd oor d t O 32 ve rho 44 rlo ug 9 Ve oke h d 66 ct T or H in rf 22 ea ad 48 r/R eq 25 Fa Alti ead u t il 43 ba Al ude ck tC In 24 TOTAL lim ad 41 ARTCC eq b/ D 7 C es u 49 Fa lim cen b il th d O 22 32 v e r ou In Terminal Radar rt gh st r u ak i 10 c ng 36 - no te -in Trf 8 m te p 23 nd er M ro ed 13 r- is 17 da ap i s s u p e ta bl l Pr 16 oc oc k- ed m is 10 8 8 en 2 Ai ter r Tr an s pa sp ce 13 12 FP ose OE Classification a/ S- 34 Sp mis c Reports Operational Errors 318 (66.04%) 162 (33.96%) 480 7 en ee t d Results Study 1: Taxonomic Study i n er 1 ad 9 W equ ro 1 n a/ g a / c 54 ov c er l C LO ap le A ar m ed bl i s M wm is in re ad ARTCC ot he info TRACON rs 1 13 12 11 03 /w 560 (69.1%) 250 (30.9%) Classification Operational Error 810 ha t 56 July 2-5 , 2007
  • 10. OEs co-occurring with TCAS Jan-Jun 04 Jan-Jun 05 Terminal Radar 8 (30.8%) 34 (43.6%) ARTCC 18 (69.2%) 44 (56.4%) TOTAL 26 78 Proportion of OE types (based on the total OE number) 20% 18.3% Full set of reports TCAS RA reports 13.8% 1 .9% 1 10.9% 9.4% 9.4% 10% 9.3% 8.9% 8.6% 8.4% 8.4% 8.0% 7.9% 6.9% 6.7% 5.7% 5.0% 4.0% 3.8% 3.7% 3.5% 3.2% 2.5% 1.0% 0% Altitude Inadequate Instruction not Fail Converging Descend through Climbing/Descending Climb through Fail Overtaking Traffic Temporal error-issue Overlooked Traffic Vector Inadequate Hearback / Readback Control coordination Fail Identification Intended Altitude Slide 10 July 2-5 , 2007
  • 11. ATC Commands IN TCAS Situations ATC Com m ands In RA OE 45 40 35 30 25 % of 104 Series1 20 15 10 5 0 Before RA After RA None Undetermined Slide 11 July 2-5 , 2007
  • 12. ATC Commands Dependence on Information Integrity Inform ation Integrity 40 35 30 25 % of 59 Reports Complete Info 20 Incomplete Info 15 10 5 0 Horizontal:Before Vertical: Before Horizontal:After Vertical: After None RA RA RA RA Slide 12 July 2-5 , 2007
  • 13. ATC Vertical Commands after RA and Flight Deck Report Vertical Com m ands After RA 60 50 40 % Correct out of 20 30 Series1 20 10 0 Vertical Correct Vertical In Opposition Slide 13 July 2-5 , 2007
  • 14. Deviations from “expected” behavior Clearances issued by controller upon triggered TCAS RA 25 NO REPORT COMPLETE INCOMPLETE % of incidents 20 4.8 opposite to RA 0 opposite to RA 15 6.5 Traffic 12.9 Heading 10 17.7 4.8 Altitude 12.9 14.5 5 9.7 8.1 8.1 3.2 1.6 0 Before After None Before After None Before After None Incomplete = missing any pilot’s message, missing callsign, TCAS direction or excessive delay Before and after refers to the action of controller in relation to the TCAS RA event. Traffic, heading, or altitude mean ATCO gave traffic info, or change heading, or altitude Slide 14 July 2-5 , 2007
  • 15. Highlights on the chain of events during TCAS RA encounters in OE reports • Controllers issued clearances after TCAS RA in the vertical plane in 13 situations (21 %). • Controllers received incomplete information in 26 situations (43.5%) and no information in 3 (5%). Opportunities for wrong decisions. • Controllers issued vertical clearances after TCAS RA and incomplete pilot’s reports in 12 situations (19.4 %). • opposite altitude clearance in 3 reports (4.8%) – Pilot reports were all late after TCAS RA and controller clearance • Data suggests that it is more likely to receive an opposite clearance if the controller receive incomplete pilot information. Slide 15 July 2-5 , 2007
  • 16. Proposed Actions • Increase training recreating TCAS RA situations Under stress situation, abnormal events trigger more familiar responses (i.e., issue vertical clearance) • Revisit downlinking RAs Future research needed Not obvious solution, with important implications • Draw too much controller attention • TCAS RA is not the most relevant information, but the pilot deviation from clearance • Controller’s responsibility and liability implications Slide 16 July 2-5 , 2007
  • 17. Conclusions • Value of systematic characterization of errors OE classification would allow prioritization of actions. Failure to notice converging aircraft, control coordination, hearback/readback, and overlook traffic are the most frequent • Error reports concurrent with TCAS RA: OEs with similar patterns to full dataset Not consistent pilot-controller behavior (deficient information/actions) Incomplete/late information increases chances of vertical clearances incompatibles with RA direction Slide 17 July 2-5 , 2007
  • 18. Acknowledgement • Special thanks for comments on this paper and insightful ideas during the study to Dr. Kim Cardosi (Volpe Laboratories) & Ms. La Gretta Bowser (FAA) • Thanks to Mr. Bill Davis (OSTP) for his sponsorship and comments Slide 18 July 2-5 , 2007
  • 19. Questions Slide 19 July 2-5 , 2007
  • 20. Back Up slides Slide 20 July 2-5 , 2007
  • 21. Proximity Rating • Proportion of higher-proximity events in terminal areas. • Errors with low frequencies have higher proximity (reduced cross check) ARTCC TRACON Proximity Rating A 7 (2.1 %) 51 (33.3%) Proximity Rating B 31 (9.5 %) 65 (42.5 %) Proximity Rating C 285 (86.9%) 21 (13.7 %) No rated 5 (1.5 %) 16 (10.5%) (Chi-square X2 (2,N=460)=226, p<0.001) Slide 21 July 2-5 , 2007
  • 22. Error Severity and Frequency by Time on Shift • No statistical significance in the distribution of frequencies (60 min.) • Not been able to claim that errors are more likely after break relief or transition into position. • No evidence that errors were more severe in the first 30 minutes after taking over control (X2 (10,N=373)=7.27, p=0.700) 40 38 37 37 35 35 35 33 32 32 30 30 28 27 OE Frequency 24 25 20 18 15 13 11 10 10 8 7 5 4 4 4 5 1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 110 120 > 120 Minutes on Position (Chi-square X2 (11,N=388)=6.575, p=0.832) Slide 22 July 2-5 , 2007
  • 23. TCAS RA and the proximity of aircraft • Higher proximity when TCAS RA is triggered (only in centers we could proof statistically) • Smaller than expected. Consequence of time logic implemented by TCAS, and/or Proof of global efficiency of TCAS (“safe the day”) Proximity rating of OE 80% 70% 2.1% 60% 0.0% 50% Unk C 40% 1.0% 40.4% B 7.7% 59.4% 3.1% A 30% 6.5% 18.3% 20% 13.5% 14.4% 10% Centers (Chi-square=32.037, p<0.001) 13.5% 10.6% 4.4% TRACON (Chi-square=0.254, p=0.88) 4.8% 1.5% 0% TRACON (RA) TRACON ARTCC (RA) ARTCC Slide 23 July 2-5 , 2007

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