Ice crystals or light snow are then raised aloft and reduce horizontal visibility, producing a whiteout. Wind favours the development of BLSN aloft if associated with mechanical turbulence or an unstable air mass. Do not trust overcast ceilings, even light precipitation and winds stronger than 15 kt. Before deciding to depart, you would do well to analyse weather briefings and forecasts. Unfortunately, this is not always possible. Discounting the possibility of staying on the ground, an IFR flight would be your best bet to minimize the hazards of whiteout. In the areas of the far north it is not easy to fly VFR in completely overcast weather. In this case, the weather conditions in which you are willing to fly will be a determining factor. Prevention and preparationĪs we have no control over this kind of phenomenon, the only ways to reduce the hazards of whiteout are to:Īvoiding whiteout is not easy, especially if you are flying in areas above the tree line (the limit on mountains and high latitudes beyond which trees will not grow because of the cold). The best-case scenario would be for you to come away with one more piece of experience to your credit as a pilot, without bending metal. As it is impossible to determine your altitude visually, slow descent might not be detected before impact occurs. If you do not lose control of your aircraft, you may become one more statistic in the CFIT tables. The turn may become a spiral, ending, in the worst case, in impact with the ground. No longer able to see the horizon, you may go into a turn without realizing it. Should you encounter such conditions when flying VFR, you would likely suffer spatial disorientation for lack of visual cues. Fortunately, once all the pieces came to rest, the pilot was unhurt and able to walk away." The aircraft hit the ice, and the left wing was sheared off. When he realized that the instruments were not lying, it was too late. He did not trust them, because he did not feel the turn. His instruments indicated a descending left turn. Five miles on, he encountered whiteout conditions over a lake. "The pilot of the C-185 departed in VFR conditions and climbed to 400 ft. Here is an excerpt from a TSB accident report: (See the table of weather codes in the MET section of your A.I.P.) The hazards The phenomenon can be caused or amplified by mist (BR), blowing snow (BLSN) or precipitation in the form of small ice or snow crystals (IC). Pilots flying VFR therefore lose all the essential clues for continuing their flight safely, even if visibility remains adequate and the ceiling is high.
It is impossible to make out the horizon and distance from the ground. You get the impression of being inside a bowl of milk or a ping-pong ball.
More simply put, the phenomenon occurs when you are in the presence of a large flat area and the overcast sky blends in with the ground. Whiteout occurs over an unbroken snow cover and beneath a uniformly overcast sky when, with the aid of the snowblink effect, the light from the sky is about equal to that from the snow surface. Neither shadows, horizon nor clouds are discernible sense of depth and orientation is lost only very dark, nearby objects can be seen. "An atmospheric optical phenomenon of the polar regions in which the observer appears to be engulfed in a uniformly white glow. We will focus on this phenomenon, because it holds great risks for the safety of a flight. Besides snow and cold, winter presents a number of new phenomena with which we have to come to terms. Among other things, it is wise to review your aircraft’s operations manual, check the equipment that has to be carried for winter flights and think about the weather features associated with flying in winter. Article by Francis Bélanger and Denis Veilleux, published in the November-December 1998 issue of La Brousse, reprinted with permissionĪs winter approaches, it is recommended that you review particular aspects of what the snowy season holds in store for you.
0 kommentar(er)
