Line Pilot Perspectives on Complexity of Terminal Instrument Flight Procedures [2017]

Chandra, Divya C; Markunas, Rebecca · 2017 · ROSA P / John A. Volpe National Transportation Systems Center (U.S.)

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Summary

This study addresses the operational challenges associated with the implementation of Performance-Based Navigation (PBN) Instrument Flight Procedures (IFPs), such as Standard Instrument Departures (SIDs), Standard Terminal Arrival Routes (STARs), and Instrument Approach Procedures (IAPs). While PBN technologies like Area Navigation (RNAV) and Required Navigation Performance (RNP) offer safety and efficiency benefits, their operational rollout often encounters difficulties attributed to human factors. The research was motivated by the need to understand the subjective complexity of these procedures from the perspective of line pilots, who fly these routes daily, rather than relying solely on objective design metrics or simulator data. The primary goal was to identify subjective complexity factors that increase pilot workload or confusion, while the secondary goal was to examine how pilots utilize aeronautical charts in conjunction with modern flight deck automation. The researchers conducted qualitative interviews with 45 professional line pilots from major and regional airlines, corporate operators, and air taxi services. Participants were grouped by operator and aircraft type to observe their natural briefing processes. In a meeting room setting, groups of two or three pilots reviewed and briefed two SIDs, two STARs, and two IAPs using Jeppesen charts, followed by detailed discussions to identify areas of potential confusion regarding the IFP design or chart depiction. This method allowed researchers to focus on cognitive processing and chart interpretation without the distraction of real-time flying tasks. The study analyzed pilot feedback to categorize issues into IFP design, chart design, and operational factors. The findings identified a broad range of complexity drivers, organized into a subjective complexity framework. IFP design issues were the primary driver, including excessive flight path constraints, complex transitions, and non-smooth energy profiles. Chart-related issues included visual density, inconsistent altitude specifications, and unclear graphical connections between chart sections. The study also highlighted "operational complexity" factors outside designer control, such as Air Traffic Control interventions, aircraft equipment variations, and crew dynamics. Specific examples of confusion included mismatched speed constraints between holding patterns and arrival routes, and ambiguous notes that applied only to specific runways but were visually highlighted for all. Pilots demonstrated varying strategies for managing these complexities, often relying on automated systems while maintaining heightened vigilance for non-standard constraints. The significance of this work lies in its contribution to human factors engineering for the Next Generation Air Transportation System (NextGen). By defining subjective complexity and separating it from operational factors, the study provides actionable recommendations for IFP and chart designers. Key recommendations include minimizing flight path constraints and transitions, ensuring smooth energy profiles, using pronounceable waypoint names, and clarifying chart notes. The findings suggest that IFP designers must account for operational realities and aircraft automation limitations to reduce pilot workload. This research offers a foundation for improving the usability and safety of terminal airspace procedures, emphasizing that successful implementation requires coordinated efforts among designers, regulators, and operators to mitigate confusion and error potential.

Key finding

IFP design issues are the biggest driver of subjective complexity, inducing issues with overall chart design and affecting chart-specific issues, while operational complexity factors such as ATC interventions and aircraft equipment variation remain outside the direct control of IFP designers.

Methodology

lab_experiment

Sample size: 45

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

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• situation awareness theory