Psychological factors are those factors that impose an additional processing load in the conscious brain. When these factors are present, the pilot may experience task saturation; a condition where there is more information that must be processed than the conscious brain can handle. This may allow dangerous flight conditions to persist until time to successfully recover is no longer available. Psychological factors may include instrument /navigation flying, low level flying, a contingency situation (such as an in- flight emergency), or visual navigation under degraded visual conditions.
Physiological factors are those that degrade the pilot’s ability to perform. Unlike the environmental factors and the psychological factors, the pilot can directly influence whether physiological factors are or are not present during flight. By far the most common physiological factor is fatigue. Fatigue impairs concentration; simple tasks become difficult and difficult tasks may become impossible when the pilot is fatigued.
Studies conducted by aviation researchers at the University of Illinois in the 1990s estimated that, on average, it took 178 seconds for VFR pilots exposed to simulated IMC conditions to become spatially disoriented. 9 The studies were described in an article published in Flight Safety Australia, which recounts the following:
They took 20 VFR pilots and got them to fly into instrument meteorological conditions (IMC) in specially programmed flight simulators. All of the pilots in the study went into graveyard spirals that would have ended in uncontrolled flight into terrain or rollercoaster-like oscillations that became so intense that they would have resulted in structural failure of the aircraft.
A spiral dive can be defined as a steep descending turn where the aircraft is in an excessively nose-down attitude, and where the airspeed increases rapidly. A pilot can get into a spiral dive by allowing the attitude of the nose to become too low, due to excessive bank while in a steep turn. If an attempt is made to raise the nose, then the spiral tightens and there is a rapid loss of height and an increase in speed. Transport Canada identifies spatial disorientation and the absence of a visible horizon as contributing factors to spiral dives. 10
Final Minutes of Flight
Once established on the second approach, the aircraft altitude and heading were maintained which is consistent with the autopilot being engaged.
Paul Cummins and staff writers, “178 Seconds to Live VFR into IMC”, Flight Safety Australia, January–February 2006.
Transport Canada, TP185-4-99-132-4127, Aviation Safety Letter, April 1999.