An understanding of how pilots complete their flight tasks is an essential element
of preventing aviation incidents. Disorientation or a loss of control of the aircraft are
some direct causes of such events. This study seeks to assess the impact of environmental
factors on the ability of general aviation pilots to complete flight tasks.
Certified Pilots (n=16) with experience flying a Cessna 172 or similar aircraft
participated. They were tasked with flying a virtual model of a Cessna 172 Skyhawk.
This was accomplished using X-Plane 11 flight simulation software, Honeycomb Alpha
flight controls, and a Saitek throttle quadrant. The software was integrated with an HTC
Vive Pro virtual reality headset. Within X-Plane 11, three environmental conditions were
created: Clear, Partial Clouds (Partial Cover), and Full Clouds (Total Cover). All weather
conditions other than cloud cover were the same across the environments with no wind
present. No clouds are present in the Clear environment. Roughly 50% of the ground is
obscured by clouds in the Partial Clouds environment. The ground is completely
obscured by clouds in the Full Clouds environment. While in an environment, pilots were
tasked with performing a series of 500 ft ascents, 500 ft descents, 90° turns to the right,
and 90° turns to the left. These tasks were completed above the cloud layers of the
environments. During Day A, the pilots flew in each of the environments twice. During
Day B, pilots flew in the Full Clouds environment twice and were exposed to hypoxic air
during one of those times. The hypoxic air is 10% oxygen and simulates an altitude of
approximately 14,000 ft. The pilots were assessed based on their altitude error, heading
error, heading rate of change, task duration, and the amount of motor control effort that
was required to complete the task.
When flying in environmental conditions that have fewer visual cues such as the
Total Cover condition, pilots experienced more error and had to exert more effort to
complete the tasks. Visual condition proved to be a statistically significant factor for
aileron effort during the altitude tasks (ascents and descents) (p=0.0001, P=1.00),
duration of the altitude tasks (p=0.0001, P=1.00), the final heading error of the heading
tasks (turns to the right and turns to the left) (p=0.0030, P=0.87), and the duration of the
heading tasks (p=0.0001, P=1.00). A trend towards statistical significance of visual
condition was observed for the final altitude error of the heading tasks (p=0.0581,
P=0.56) and the aileron effort of the heading tasks (p=0.0656, P=0.54). The direction of
the task proved to be a significant factor for the final altitude error of the altitude tasks
(p=0.019, P=0.65), the aileron effort of the altitude tasks (p=0.0001, P=0.99), the elevator
effort of the altitude tasks (p=0.0001, P=0.99), the duration of the altitude tasks
(p=0.0001, P=1.00), the final altitude error of the heading tasks (p=0.00297, P=0.84), and
the final heading error of the heading tasks (p=0.0001, P=0.99).
Exposure to hypoxia resulted in a decrease in performance with an increase in the
effort of the pilots. The oxygen condition was significant for the aileron effort during the
altitude tasks (p=0.000005, P=0.999) and the aileron effort during the heading tasks
(p=0.0135, P=0.71). The direction of the task also proved to be a significant factor for the
duration of the altitude tasks (p=0.03315, P=0.573), the absolute altitude error of the
heading tasks (p=0.048, P=0.51), the aileron effort of the heading tasks (p=0.0003,
P=0.96), and the duration of the heading tasks (p=0.002001, P=0.888). The significance
of the task direction reflects the torque of the engine and differences in how the pilots
perform certain tasks.
The investigation of flight behaviors continues from here with a closer
examination of variability of pilot behaviors during tasks. Additionally, the physiological
data collected as part of this study still needs to be integrated with the flight data. Finally,
the study will be repeated with an active motion platform to investigate the effects of
vestibular feedback on pilot performance.