During the planning phase, pilots should identify and brief their EDTs.


EDTs are those conditions that, when encountered, trigger a predetermined deci- sion (due to weather, degraded visibility, etc.). These EDTs can include airspeed, alti- tude, or divergence from the planned route. The H-SE team opted to provide exam- ples of conditions that may be used to create an EDT (depending on the situa- tion) rather than recommend specific parameters that must be used (see Spatial Disorientation Induced by a Degraded Visual Environment: Training and Decision- Making Solutions, Helicopter Safety Enhancement No. 127A, Output No. 2). The predetermined decisions depend on pilot and equipment capabilities. Examples


include: ■ Land the aircraft ■ Commit to instruments ■ Turn to KNOWN good-weather conditions.


Emergency Response While most pilots agree that instances of decreasing visibility are cause for concern and can lead to an in-flight emergency, most pilots don’t treat this emergency the same as emergencies caused by aircraft systems. For example, a pilot experiencing a


WARNING light in the event of an engine fire or a CAUTION light indicating troubling transmission pressure wouldn’t second- guess the rotorcraft flying manual and con- template alternate courses of action. However, research is teeming with


examples of pilots who continued into degraded visibility—flights that should have generated an internal CAUTION or WARNING light in the pilot’s head and a corresponding in-flight emergency response. By establishing and briefing EDTs during the preflight planning phase, pilots are more likely to make better in-flight decisions, taking early action as they would in response to any other aircraft flight manual emergency.


Training Historically, aviation accident research highlights the importance of more effec- tive training. Survey data confirmed this finding for spatial disorientation, as well, but it also indicated a general misunder- standing of the physiological impact of spatial disorientation. Many survey respondents who believed


they had experienced SD went on to describe illusions rather than spatial disori- entation. This finding underscored a funda- mental misunderstanding of what true spatial disorientation encompasses, mak- ing recognition of the phenomenon more challenging.


A comprehensive pilot-training program should include an academic focus on understanding the mental and physical responses to encountering spatial disorien- tation. Aircraft training can be conducted in simulators or in aircraft. Limitations associ- ated with each type of training should be well understood, because they do exist, and certain outside factors (such as ops specs, simulator cost and availability, certi- fication, and so on) may preclude one approach versus the other.


Simulators are good at re-creating


low-visibility conditions and for teaching basic maneuvers and instrument flying, as well as generally representing rotorcraft handling qualities at a fairly high level. While simulators provide excellent visual illusions, however, most lack the range of motion required to create vestibular illusions. (According to the FAA, it takes 20 seconds of acceleration to create vestibular illusions.) The importance of combining visual and


vestibular illusions is critical in degraded visual environment–induced SD training. The addition of visibility simulation sys- tems to in-aircraft training offers variable control of in-aircraft visibility, providing the critical capability of re-creating both visual and vestibular illusions. Simulator and in-aircraft training should be scenario based and include decision- making as well as allow full spatial disori- entation to develop. As with all training


conducted (whether simulator or in-aircraft), safety has to be considered first and foremost.


Recovery Historically, recovery from spatial disorien- tation is often lumped in with unusual atti- tude recovery. Although the techniques can be similar, the visual and vestibular dis- orientation experienced in SD lead to an overwhelming confusion in the brain that is not the same as the Coriolis effect, in which pilots can feel as though they’re pitching, yawing, and rolling simultane- ously. SD brain confusion should be intro- duced during the training phase, but spatial disorientation is unique for each individual, during each encounter. Each aircraft provides a slightly different


set of variables during recovery, including stability augmentation systems, trim sys- tems, and autopilot variants. Despite the many differences in aircraft, a combination of power, attitude, and balance (PAB) can be employed. Pilots who encounter SD


should: ■ Power: set power that will allow for a normal climb rate; care must be taken not to induce a rapid climb rate that can further disrupt the pilot’s vestibular system


■ Attitude: level the wings, place the nose on the horizon


■ Balance: place and keep the aircraft in trim. This combination of actions minimizes


the instrument scan. In summary, better decision-making


during every phase of flight is critical to avoid conditions conducive to spatial disori- entation. Training should include scenarios emphasizing techniques to improve both aeronautical decision-making and the abil- ity to recognize the onset of and recovery from visual and vestibular illusions. H-SE 127A outlines these intervention strategies and provides a list of resources for pilots to consult to develop better knowledge and appreciation of the dan- gers posed by low-visibility conditions lead- ing to spatial disorientation.


DECEMBER 2022 ROTOR 57


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