Improving rotorcraft deceleration guidance for brownout landing.

摘要

The BOSS symbology for rotorcraft is specifically designed to provide the pilot with the necessary information and guidance to safely land in brownout environments. From the last BOSS study, issues were brought forth regarding the longitudinal velocity algorithm, which sets up a deceleration profile and commands the forward speed of the aircraft throughout the approach. Pilots commented that the algorithm lead the aircraft to be too slow for too long, effectively prolonging the brownout. Thus the purpose of this study was to investigate new algorithms to enable a faster approach with less time spent in brownout. The previous deceleration algorithm was also not robust in its ability to provide consistent guidance at variable starting distances and starting velocities. Therefore a new algorithm was developed capable of providing more consistent guidance from various starting positions and velocities. Additionally, through manipulation of its parameters, it was found possible to reduce the amount of time spent at low speeds in the approach. Four algorithms were subsequently developed with varying levels of aggressiveness. Eight highly skilled pilots participated in a simulation study using a generic fixed-base simulator with a high-fidelity rotorcraft H-60 model. Results found that as the aggressiveness of the algorithm increased, the time spent at low speeds and in brownout significantly decreased. Concurrently the pitch of the aircraft (and resulting deceleration) significantly increased, though the pitch values were within reasonable limits for IMC flight according to previous literature. One of the new algorithms was found to significantly reduce the amount of time spent at low speeds by 24% and also received the highest preference ranking and the highest comfort ratings.