Spatial Orientation Modeling: Use of Multisensory Cueing to Prevent Vection Illusions

There are many conditions in the aerospace environment causing pilots to experience visually induced illusions of self-motion referred to as vection. These compelling illusions of self-motion are often induced by motion of large portions of the visual environment. Many mishaps, especially in the helicopter community, are attributed to vection which is one cause of spatial disorientation and the loss of situation awareness. The Tactile Situation Awareness System (TSAS) developed by the US DoD and NASA in a collaborative effort with Australia uses the sense of touch to provide situation awareness information to pilots. It presents information including aircraft position, attitude, altitude, acceleration and velocity through the use of tactile stimulators distributed on the torso and placed in the seat cushion and shoulder straps. The potential safety benefits of TSAS include reduced spatial disorientation mishaps, improved situational awareness, improved pilot control, and reduced pilot workload during critical flight maneuvers such as hovering in zero visibility, flight transitions, approach and landing. In two series of in-flight experiments conducted in the US and Australia, in which tactile cueing was used to provide helicopter pilots an additional source of velocity information under high workload conditions during degraded visual environments, two-of-six test pilots in one group and one-of-one test pilot in the second group experienced momentary vection. Pilots wearing the tactile cueing system either did not experience illusions or were made aware of the illusion and experienced only a momentarily false perception due to accurate presentation of drift information from the tactile cue. The continuous tactile cueing during periods of distraction away from visual instruments permitted pilots in both groups to maintain situation awareness and recover from momentary spatial disorientation. The novel Australian tactile cueing system incorporated additional features to include more torso coverage and piezoceramic tactors which may provide more effective salient tactile cueing. During the Apollo 11 moon landing the commander likely experienced a vection illusion and stated in a post flight self-critique session that during the critical landing phase “I think I was probably over controlling a little bit in lateral. I was confused somewhat in that I couldn't really determine what my lateral velocities were due to the dust obscuration of the surface. - I felt I was a bit erratic”. With the recent incorporation of auditory and somatosensory information, to include tactile cueing, into spatial orientation models, we now have the ability to recommend improved approaches to maintain spatial orientation in various environments. In aerospace conditions it appears that multisensory cueing from non-visual, continuous orientation sources is the best approach to MAINTAIN spatial orientation and prevent spatial disorientation from occurring.