Comparing Active and Passive Just Noticeable Difference Thresholds for Stall Abruptness in Symmetric Stall

Abstract

Aerodynamic stall has been a critical factor in recent aircraft crashes, leading to revisions in the regulations on the fidelity of stall models in flight simulation training devices. However, the updated regulations still lack a clearly defined accuracy required for effective pilot training. To determine the required accuracy, this research investigates how the Just Noticeable Difference (JND) thresholds for the stall abruptness parameter translate from a passive, observer task to an active flying task. An experiment was performed in the SIMONA Research Simulator with 16 active pilots, who performed two separate experiments. In one experiment, a stall autopilot flew the maneuver during which a staircase procedure was used to determine the passive JND threshold. The JND thresholds of a1 = 0.11 ± 0.094 found in this experiment were lower than the JND thresholds of a1 = 0.16 ± 0.14 found in a similar experiment by previous research. In the other experiment, the method of constant stimuli was used to determine the JND threshold for the active flying scenario. A psychometric curve, based on the Gaussian cumulative distribution function, was fitted using the combined responses of the participants. The resulting psychometric function of the active experiment lies entirely to the right of the passive psychometric function, and, when comparing the 75% thresholds for both experiments, the active threshold was found to be five times higher than the passive threshold. This indicates a decreased sensitivity to changes in stall abruptness when pilots are flying a stall themselves.