The effect of aircraft control forces on pilot performance during instrument landings in a flight simulator

Background: Pilots may have difficulty controlling aircraft at both high an d low force levels due to larger variability in force production at these f orce levels. The aim of this study was to measure the force variability and landing performance of pilots during an instrument landing in a flight sim ulator. Methods: There were 12 pilots who were tested while performing 5 in strument landings in a flight simulator, each of which required different c ontrol force inputs. Pilots can produce the least force when pushing the co ntrol column to the right, therefore the force levels for the landings were set relative to each pilot's maximum aileron-right force. The force levels for the landings were 90%, 60%, and 30% of maximal aileron-right force, no rmal force, and 25% of normal force. Variables recorded included electromyo graphic activity (EMC), aircraft control forces, aircraft attitude, perceiv ed exertion and deviation from glide slope and heading. Multivariate analys is oi variance was used to test for differences between landings. Results: Pilots were least accurate in landing performance during the landing at 90% of maximal force (p < 0.05). There was also a trend toward decreased landi ng performance during the landing at 25% of normal force. pilots were more variable in force production during the landings at 60% and 90% of maximal force (p < 0.05). Conclusion: Pilots are less accurate at performing instru ment landings when control forces are high due to the increased variability of force production. The increase in variability at high force levels is m ost likely associated with motor unit recruitment, rather than rate coding. Aircraft designers need to consider the reduction in pilot performance at high force levels, as well as pilot strength limits when specifying new sta ndards.