Startle is an uncontrollable, automatic muscle reflex, raised  heart rate, blood pressure, etc., elicited by exposure to a  sudden, intense event that violates a pilot’s expectations. The ability to separate time-critical information from  distractions takes practice, experience and knowledge of the  airplane and its systems. Cross-checks are necessary not only  to corroborate other information that has been presented, but  also to determine if information might be missing or invalid.  For example, a stall warning system may fail and therefore  not warn a pilot of close proximity to a stall, other cues  must be used to avert a stall and possible LOC-I. These cues  include aerodynamic buffet, loss of roll authority, or inability  to arrest a descent. Surprise is an unexpected event that violates a pilot’s  expectations and can affect the mental processes used to  respond to the event. Spatial disorientation has been a significant factor in  many airplane upset accidents. Accident data from 2008  to 2013 shows nearly 200 accidents associated with spatial  disorientation with more than 70% of those being fatal. All  pilots are susceptible to false sensory illusions while flying  at night or in certain weather conditions. These illusions  can lead to a conflict between actual attitude indications  and what the pilot senses is the correct attitude. Disoriented  pilots may not always be aware of their orientation error.  Many airplane upsets occur while the pilot is engaged  in some task that takes attention away from the flight  instruments or outside references. Others perceive a conflict  between bodily senses and the flight instruments, and allow  the airplane to divert from the desired flightpath because  they cannot resolve the conflict.  This human response to unexpected events has traditionally  been underestimated or even ignored during flight training.  The reality is that untrained pilots often experience a state  of surprise or a startle response to an airplane upset event.  Startle may or may not lead to surprise. Pilots can protect  themselves against a debilitating surprise reaction or startle  response through scenario-based training, and in such  training, instructors can incorporate realistic distractions to  help provoke startle or surprise. To be effective the controlled  training scenarios must have a perception of risk or threat  of consequences sufficient to elevate the pilot’s stress  levels. Such scenarios can help prepare a pilot to mitigate  psychological/physiological reactions to an actual upset. Upsets are not intentional flight maneuvers, except  in maneuver-based training; therefore, they are often  unexpected. The reaction of an inexperienced or inadequately  trained pilot to an unexpected abnormal flight attitude is  usually instinctive rather than intelligent and deliberate. Such  a pilot often reacts with abrupt muscular effort, which is  without purpose and even hazardous in turbulent conditions,  at excessive speeds, or at low altitudes.  A pilot may experience spatial disorientation or perceive the  situation in one of three ways: Without proper upset recovery training on interpretation and  airplane control, the pilot can quickly aggravate an abnormal  flight attitude into a potentially fatal LOC-I accident.  Consequently, UPRT is intended to focus education and  training on the prevention of upsets, and on recovering from  these events if they occur.  [Figure 4-14] For detailed information regarding causal factors of  spatial disorientation, refer to Aerospace Medicine  Spatial Disorientation and Aerospace Medicine Reference  Collection, which provides spatial disorientation videos.  This collection can be found online at: www.faa.gov/about/ office_org/ headquarters_offices/avs/offices/aam/cami/ library/online_libraries/aerospace_medicine/sd/videos/. 4-19 • Upset prevention refers to pilot actions to avoid a  divergence from the desired airplane state. Awareness  and prevention training serve to avoid incidents;  early recognition of an upset scenario coupled with  appropriate preventive action often can mitigate a  situation that could otherwise escalate into a LOC-I  accident.  3.  Incapacitating spatial disorientation: the pilot is unable  to affect a recovery due to some combination of: (a)  not understanding the events as they are unfolding,  (b) lacking the skills required to alleviate or correct  the situation, or (c) exceeding psychological or  physiological ability to cope with what is happening.  2.  Unrecognized spatial disorientation: the pilot is  unaware that an upset event is developing, or has  occurred, and fails to make essential decisions or take  any corrective action to prevent LOC-I. 1.  Recognized spatial disorientation: the pilot recognizes  the developing upset or the upset condition and is able  to safely correct the situation. Upset Prevention and Recovery Training (UPRT) Spatial Disorientation Surprise Response Startle Response