FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-26/02

Title and Subtitle: Use of a Monocular and Binocular Head-Worn Display in Lieu of a Head-Up Display During Approach, Landing, and Rollout: Human Factors Evaluation of Pilot Performance and Workload

Report Date: January 2026

Authors: David C. Newton (0000-0002-3112-3316), Eric T. Greenlee (0000-0001-9433-6434), Theodore C. Mofle (0000-0003-2217-9083), Farzaneh Shahini (0000-0002-1514-5312), Rebecca DiDomenica (0009-0009-4726-578X), Inchul Choi (0000-0002-2048-7026), and Ryan Weaver

Abstract:
The approach, landing, and rollout is a complex, critical operation for pilots of fixed-wing aircraft, particularly when flight visibility is limited by weather. To enhance the safety of this operation, aircraft can be equipped with a Head-Up Display (HUD), which presents flight symbology on a transparent screen at a focal distance of optical infinity so that the pilot can view primary flight information while maintaining visual contact with the runway. The Head-Worn Display (HWD) is an emerging technology that is designed to provide the benefits of a HUD. However, it may incorporate optical differences that impact pilots’ performance and workload. HWDs can be binocular (i.e., displaying symbology to both eyes) or monocular (i.e., displaying symbology to a single eye). When flying with a monocular HWD, binocular rivalry may impact the pilot’s ability to use the symbology and impose greater demands on the pilot’s attention. This raises questions about whether using a monocular HWD impacts pilots’ flying performance, elevates workload, and increases the risk of attentional tunneling. Pilot performance and workload may also be impacted by the physical and optical differences of the HWD relative to those of the HUD. To address these concerns, a study was carried out in which 24 pilot crews, each consisting of two Airline Transport Pilot (ATP) Captains, flew approach and landing scenarios with varying visibility levels, some of which included non-normal events, in a Boeing 737 Level D-equivalent flight simulator while using flight symbology presented on a HUD, binocular HWD, and monocular HWD. Simulator motion was disabled in the study to prevent interference with the HWD head tracking system. Quantitative measures of pilot flying performance were implemented to evaluate the effects of each display type on flightpath and energy management, landing and rollout performance, and response to non-normal events. Pilots rated their workload during each scenario using the National Aeronautics and Space Administration Task Load Index (NASA-TLX). The findings of this study suggest that a monocular HWD may not have a substantial impact on a pilot’s ability to manage the flightpath and energy state during approach, landing, and rollout operations. However, pilots experienced a higher workload when flying with the monocular HWD than with the binocular HWD and HUD. There were impacts on landing performance and runway incursion detection attributable to the optical characteristics of the HWD relative to those of the HUD, as well as the monocular versus binocular configuration of the HWD. Ultimately, this research contributes to the understanding of how visual attention is impacted by monocular viewing and provides operational takeaways for the use of an HWD in lieu of a HUD during low-visibility flight operations.

Key Words: Advanced vision systems, binocular rivalry, extended reality, flight technical error, head-mounted display, head-up display, head-worn display, low-visibility operations, pilot performance, pilot response time, pilot workload, runway incursions

No. of Pages: 106