Effect of Free Flight Conditions on Controller Performance, Workload, and Situation Awareness
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Summary
This study investigates the impact of "free flight" concepts on air traffic controller (ATC) performance, workload, and situation awareness (SA). Free flight represents a shift in the National Airspace System where aircraft are no longer restricted to fixed air corridors, allowing pilots greater control over routes and deviations. The research was motivated by concerns that this increased flexibility could compromise safety by reducing the predictability of aircraft movements, thereby degrading controllers' ability to maintain an accurate mental representation of traffic. The study aimed to evaluate these effects using current technology and controller capabilities, specifically examining how varying levels of pilot autonomy affect controller monitoring and separation functions. The experiment utilized a within-subjects design with ten full-performance ATC specialists from the Jacksonville Air Route Traffic Control Center. Participants controlled traffic in a simulated sector using the ATCoach simulation platform across four conditions: a baseline condition with standard procedures; direct routing; direct routing with deviations requiring intent notification; and direct routing with deviations without intent notification. Data collection included objective performance metrics, subjective workload ratings via the NASA-TLX and ATWIT instruments, and SA assessments using the Situation Awareness Global Assessment Technique (SAGAT). Subject matter experts also provided over-the-shoulder performance ratings. Results indicated that higher levels of free flight adversely affected controller SA and performance. While objective operational errors were low across all conditions, observers rated controller performance significantly lower in the free flight conditions, particularly regarding task prioritization and flight strip management. Controllers provided significantly less control information and made fewer speed changes in free flight scenarios compared to the baseline. Workload ratings via NASA-TLX increased at higher levels of free flight, although ATWIT scores showed no significant difference. Crucially, SAGAT data revealed significant losses in SA at higher free flight levels, including reduced awareness of aircraft location, callsigns, next sectors, weather impacts, and clearance conformance. Controllers demonstrated lower SA at the comprehension and projection levels, indicating difficulty in predicting future aircraft actions. The study concludes that if controllers act as passive monitors in a free flight environment, their awareness of traffic state may decrease, workload may increase, and their ability to intervene timely may be limited. The findings suggest that the reduced predictability of aircraft movements under free flight challenges the controller's ability to maintain adequate SA. The authors recommend exploring new technologies and displays to address these concerns and note that further research is needed to determine if compensating mechanisms or procedural changes can mitigate these risks. This work serves as an initial evaluation of free flight concepts, highlighting potential safety implications that must be addressed before implementation.
Key finding
Higher levels of free flight significantly degraded air traffic controllers' situation awareness and observer-rated performance while increasing subjective workload, despite low rates of objective operational errors.
Methodology
simulator
Sample size: 10
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via author_sweep_intake on 2026-05-28.
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | author_sweep | — | — | 2 | 2026-05-28 |
| archive | success | canonical_url | — | — | 1 | 2026-06-06 |
| extract | success | cached | — | — | 3 | 2026-06-10 |
| clean | success | clean | — | — | 1 | 2026-06-04 |
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| embed | success | embed | Qwen/Qwen3-Embedding-8B | — | 1 | 2026-06-04 |
| enrich | success | — | — | — | 1 | 2026-05-28 |
| promote | success | — | — | — | 1 | 2026-06-04 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 2 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 15 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
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