an unusual attitude, but would not meet the upset parameters.  While the information that follows in this section could apply  to unusual attitudes, the focus will be on UPRT. The top four causal and contributing factors that have led to  an upset and resulted in LOC-I accidents are:  Unfortunately, accident reports indicate that continued VFR  flight from visual meteorological conditions (VMC) into  marginal VMC and IMC is a factor contributing to LOC  I. A loss of the natural horizon substantially increases the  chances of encountering vertigo or spatial disorientation,  which can lead to upset.  When operating in IMC, maintain awareness of conditions  and use the fundamental instrument skills—cross-check,  interpretation, and control—to prevent an upset.  With the exception of stall-related factors, which were covered  in the previous section, the remaining causal and contributing  factors to LOC-I accidents will be discussed further below. In addition to its direct impact, an inflight anomaly or  malfunction can also lead to an upset if it diverts the pilot’s  attention from basic airplane control responsibilities. Failing  to monitor the automated systems, over-reliance on those  systems, or incomplete knowledge and experience with  those systems can lead to an upset. Diversion of attention  can also occur simply from the pilot’s efforts to set avionics  or navigation equipment while flying the airplane.  Turbulence, or a large variation in wind velocity over a short  distance, can cause upset and LOC-I. Maintain awareness of  conditions that can lead to various types of turbulence, such  as clear air turbulence, mountain waves, wind shear, and  thunderstorms or microbursts. In addition to environmentally- induced turbulence, wake turbulence from other aircraft can  lead to upset and LOC-I.  Icing can destroy the smooth flow of air over the airfoil and  increase drag while decreasing the ability of the airfoil to  create lift. Therefore, it can significantly degrade airplane  performance, resulting in a stall if not handled correctly. The margin of safety is the difference between task  requirements and pilot capabilities. An upset and eventual  LOC-I can occur whenever requirements exceed capabilities.  For example, an airplane upset event that requires rolling  an airplane from a near-inverted to an upright attitude  may demand piloting skills beyond those learned during  primary training. In another example, a fatigued pilot who  inadvertently encounters IMC at night coupled with a vacuum  pump failure, or a pilot fails to engage pitot heat while flying  in IMC, could become disoriented and lose control of the  airplane due to the demands of extended—and unpracticed— partial panel flight. Additionally, unnecessary low-altitude  flying and impromptu demonstrations for friends or others  on the ground often lead pilots to exceed their capabilities,  with fatal results.  Modern airplanes and equipment are very reliable, but  anomalies do occur. Some of these mechanical failures  can directly cause a departure from normal flight, such as  asymmetrical flaps, malfunctioning or binding flight controls,  and runaway trim.  Upsets can also occur if there is a malfunction or misuse of  the autoflight system. Advanced automation may tend to  mask the cause of the anomaly. Disengaging the autopilot  and the autothrottles allows the pilot to directly control the  airplane and possibly eliminate the cause of the problem. For  these reasons the pilot must maintain proficiency to manually  fly the airplane in all flight conditions without the use of the  autopilot/autothrottles.  A pilot’s ability to adequately correlate warnings,  annunciations, instrument indications, and other cues from  the airplane during an upset can be limited. Pilots faced with  upset situations can be rapidly confronted with multiple  or simultaneous visual, auditory, and tactile warnings.  Conversely, sometimes expected warnings are not provided  when they should be; this situation can distract a pilot as  much as multiple warnings can. Although these and other inflight anomalies may not  be preventable, knowledge of systems and AFM/POH  recommended procedures helps the pilot minimize their  impact and prevent an upset. In the case of instrument  failures, avoiding an upset and subsequent LOC-I may  depend on the pilot’s proficiency in the use of secondary  instrumentation and partial panel operations.  4-18 Sensory Overload/Deprivation Task Saturation Mechanical Factors Environmental Factors Diversion of Attention IMC Human Factors VMC to IMC 1.  Environmental factors 2.  Mechanical factors 3.  Human factors 4.  Stall-related factors 