Characterizing Pilots’ Interactions with the Aircraft Collision Avoidance System Alexandra Coso, Scottie-Beth Fleming, Amy Pritchett Sponsored by the FAA, Tom McCloy as Technical Manager
Presented by Scottie-Beth Fleming 2011 International Symposium on Aviation Psychology
Overview
Background Content Analysis Results Conclusions
Overview
Background Content Analysis Results Conclusions
Traffic alert and Collision Avoidance System (TCAS) + Pilot receives aural advisories as well as a visual representation on the Traffic Situation Display (TSD) + TCAS delivers a two stage advisory and vertical avoidance maneuver Traffic Advisory (TA) - ‘Traffic Traffic’ Resolution Advisory (RA) - ‘Climb Climb’
+ TCAS “communicates” with other aircraft TCAS systems and occasionally delivers a coordinated maneuver + Pilot is to follow an RA, even if it conflicts with ATC instructions, unless the pilot believes that safe flight operation would be jeopardized Example of a Traffic Situation Display
4
Traffic alert and Collision Avoidance System + Pilot receives aural advisories as well as a visual representation on the Traffic Situation Display (TSD) + TCAS delivers a two stage advisory and vertical avoidance maneuver
Explore factors which affect pilot’s agreement (or Traffic Advisory (TA) - ‘Traffic Traffic’ disagreement) Resolution Advisoryand (RA)compliance - ‘Climb Climb’ (or noncompliance) with + TCAS “communicates” with other collision avoidance instructions aircraft TCAS systems and occasionally delivers a coordinated maneuver + Pilot is to follow an RA, even if it conflicts with ATC instructions, unless the pilot believes that safe flight operation would be jeopardized Example of a Traffic Situation Display
5
Collision Avoidance System in a Broader Context + Pilots don’t only interact with TCAS, they also receive information from ATC and the environment + Our research is interested in examining the different factors that could affect a pilot’s response Notification and Awareness
Advised Maneuvers for Collision Avoidance
ATC Traffic Callout
Compliance
TCAS Traffic Advisory
ATC Maneuver
Visual acquisition of other aircraft
TCAS Resolution Advisory
Awareness of other aircraft via TSD 6
Pilot’s Response
Non-Compliance Personal Assessment and Maneuver Decision
Overview
Background Content Analysis Results Conclusions
NASA’s Aviation Safety Reporting System (ASRS) + Pilots independently submit safety reports with a wide variety of aviation topics + Researchers searched the online database using collision avoidancerelated search terms TCAS, ACAS, Mid-air Collision, Collision Avoidance, Traffic Advisory, Avoid a Collision, Evasive Action
+ Two coders analyzed 278 relevant reports achieving an interrater reliability of 96% agreement
8
ASRS Coding Scheme Incident Description
Encounter Conditions • • • • •
Airport Time of Day Weather Aircraft Type Phase of Flight (takeoff, landing)
• • • • •
Perceptions of the Reporting Individual
Traffic Situation Awareness • • • •
Visual Before Alert Visual After TA Visual After RA Traffic Situation Display
9
TA ATC Traffic Callout Climb RA Descend Ra (etc) ATC Maneuver
• • • •
Positive TCAS Negative TCAS Positive ATC Negative ATC
ASRS Example “I was crewing as [Second-In-Command] of an aircraft cruising at [Flight Level] 190. There was a traffic alert on TCAS. The alert was an amber target at +3,300, twelve o'clock and descending rapidly. Both pilots' eyes [were] on the situation. We noticed the aircraft moved in a zigzag. [We] received an RA to descend on TCAS. Noticed the aircraft was at +300 feet. Reported to ATC immediately that we had an RA and were descending. At the same time of reporting to ATC, I looked out for traffic and spotted a B-52 at our two o'clock position and less than one mile horizontal. Looks like if we hadn't taken evasive action there could have been a collision. We descended until the TCAS advised us that we were clear of conflict. We descended to 18,300. Once clear of traffic we climbed back to assigned altitude of [Flight Level] 190. I listened to ATC tell the other aircraft he should have been at block altitude of 22,000 to 20,000 feet, thank goodness for TCAS.” ACN: 879699, 2010
Statement There was a traffic alert on TCAS. The alert was an amber target at +3,300, twelve o'clock and descending rapidly [We] received an RA to descend on TCAS Reported to ATC immediately that we had an RA and were descending. At the same time of reporting to ATC, I looked out for traffic and spotted a B-52 at our two o'clock position and less than one mile horizontal. I listened to ATC tell the other aircraft he should have been at block altitude of 22,000 to 20,000 feet, thank goodness for TCAS.
10
Incident Description TA
Traffic Situation Awareness
Perceptions
Traffic Situation Display Descend RA Complied with RA Visual Acquisition After RA Positive Perception of TCAS
Overview
Background Content Analysis Results Conclusions
Reminder of Purpose
Explore factors which affect pilot’s agreement (or disagreement) and compliance (or noncompliance) with collision avoidance instructions
12
Reported TCAS Compliance Reported Compliance to RA (n=248) Compliance 192 77.40% Partial Compliance 25 10.10% Noncompliance 19 7.70% Unspecified 12 4.80%
• Partial Compliance – Pilots added a horizontal component to their vertical avoidance maneuver – Many pilots expressed that adding a horizontal component was in compliance with TCAS regulations “As the Pilot Flying, the First Officer appropriately initiated a descending lefthand turn away from target per the aural and visual guidance from the TCAS” ACN: 802766, 2008
13
Reported TCAS Compliance Reported Compliance to RA (n=248) Compliance 192 77.40% Partial Compliance 25 10.10% Noncompliance 19 7.70% Unspecified 12 4.80%
• Noncompliance – Pilots commented they believed they were already clear – Some pilots commented they had already established visual acquisition prior to the RA – A few pilots believed TCAS was directing them into traffic “I noticed that the TCAS depicted traffic was slightly behind us and to our left on my NAV display. The Captain immediately called something to the effect of, I’ve still got him, we’re clear” ACN: 841821, 2009 14
Relationship Between Reported Compliance and Traffic Situation Awareness Reported Compliance to RA (n=248) Compliance 192 77.40% Partial Compliance 25 10.10% Noncompliance 19 7.70% Unspecified 12 4.80% + There is a high likelihood that if a pilot reported compliance with an RA,
they had visually acquired the other aircraft † they had awareness of the other aircraft’s location ‡
†χ2(2,
N = 233) = 10.990, p < 0.01 ‡ χ2(2, N = 233) = 7.291, p < 0.05 15
Reported ATC Compliance Reported Compliance to ATC Instructions (n=78) Compliance 43 55.10% Partial Compliance 15 19.20% Noncompliance 20 25.60%
• Noncompliance – Pilots reported receiving both a TCAS RA and ATC maneuver and choose to follow the TCAS RA – Others chose not to comply because they had previously established awareness of conflicting traffic via the TSD or visual acquisition – Some pilots reported believing ATC instructions would not have resolved the conflict “Traffic was depicted on TCAS, as we were converging traffic continued to head directly towards us and climbing up to our altitude. ATC issued a turning and climbing clearance to avoid conflicting traffic. I refused that clearance as I felt that would have caused a near midair or worse” ACN: 862593, 2009 16
Generalized Timeline of Events
Notification and Awareness
Advised Maneuvers for Collision Avoidance
ATC Traffic Callout
Compliance
TCAS Traffic Advisory
ATC Maneuver
Visual acquisition of other aircraft
TCAS Resolution Advisory
Awareness of other aircraft via TSD
17
Pilot’s Response
Non-Compliance Personal Assessment and Maneuver Decision
Generalized Timeline of Events
TCAS Traffic Advisory
18
TCAS Resolution Advisory
Compliance
Awareness in the Context of Collision Avoidance Reported Timing of Pilot Response to an Event (n=230) Pilot Maneuvered Before a TCAS Advisory 23 10.00% Pilot Maneuvered After a TA and Before an RA 31 13.48% Pilot Maneuvered After an RA 176 75.22% Timeline of Events
Receives TA
Establish awareness of other aircraft
Assess situation
Perform Maneuver
Receives RA
+ In cases where a pilot reported maneuvering after a TA and before an RA, the pilot also reported awareness of the other aircraft 84% of the time†
†χ2(1,
19
N = 278) = 6.952, p < 0.01
Awareness in the Context of Collision Avoidance Timeline of Events
Establish awareness of other aircraft via TSD
Assess situation
Perform Maneuver
Receives RA/ATC Instructions
+ If a pilot performed a collision avoidance maneuver before receiving instructions from TCAS or ATC, there is a high likelihood that the pilot had previously established awareness of another aircraft via the TSD†‡
†χ2(2,
N = 221) = 7.657, p < 0.03 ‡ χ2(2, N = 256) = 10.403, p < 0.01 20
Compliance in the Context of Collision Avoidance Timeline of Events
Notified via TCAS advisory
Receives RA
Complies with advisory
+ A pilot is more likely to comply with TCAS instructions if he or she was first notified to the situation by TCAS, through either the RA itself or a TA†
†χ2(4,
21
N = 229) = 14.059, p < 0.01
Interpretation of Information Timeline of Events
Notified by TCAS advisory or ATC traffic callout
Delays Response
Receives RA/ATC Instructions
Performs Maneuver
+ If a pilot is directed to a traffic situation by either ATC or TCAS, they will most likely delay any response until prompted by an RA or ATC instructions †‡
†χ2(4,
N = 227) = 22.739, p < 0.01 ‡ χ2(2, N = 267) = 9.266, p < 0.01 22
Overview
Background Content Analysis Results Conclusions and Future Work
Conclusions and Future Work + Cues (such as the TSD, TA’s, and ATC callouts) are important factors to pilot response The results of this analysis are being used to frame a TCAS study that will begin this summer
+ TSD is checked often and is useful in collision avoidance One stage of the study is to modify the TSD, and results have helped guide important features and pitfalls of the display
+ Pilots don’t always interpret cues correctly or understand the collision avoidance system Another stage of the study will be to improve training in the aircraft collision avoidance system
24
Acknowledgments
The Federal Aviation Administration (FAA), with Tom McCloy acting as technical manager
25
