What Is the Definition of Mountain Obscuration

16.2.2 Mountain blackening. Mountain darkening is a condition in which mountains or ridges are obscured by clouds, precipitation, smoke, or other darkening. Flying over mountain roads can be especially dangerous when the mountains are covered. Large differences in altitude around mountains can make surface weather observations misleading. For example, a weather station in a valley may report visual flight rules (VFR) cloud cover, while a hiker in the mountains may see fog. e. Understanding the darkening of the mountain. The term Mountain Obscuration (MTOS) is used to describe a visibility condition that differs from IFR because ceilings are described as “above ground level” (AGL) by definition. In mountainous terrain, clouds can form at significantly higher altitudes than the weather station and, at the same time, the tops of nearby mountains can be obscured by poor visibility. In these areas, the ground level can vary greatly, even over a small area. Be careful when using VFR on top. You might be operating closer to the terrain than you think because the mountain tops are hidden in a cloud bridge below.

MTOS zones are identified daily at the Aeronautical Meteorology Centre at the following address: www.aviationweather.gov. i. Effects of density height. Performance figures in the aircraft owner`s manual for take-off length, power, climb rate, etc. are generally based on standard atmospheric conditions (59 degrees Fahrenheit (15 degrees Celsius), pressure 29.92 inches of mercury) at sea level. However, inexperienced pilots, as well as experienced pilots, can get into trouble if they encounter completely different conditions. This is especially true in hot weather and at higher altitudes. Air operations at altitudes above sea level and above normal temperatures are common in mountainous areas. Such operations often lead to a drastic reduction in aircraft performance due to changes in air density.

Density height is a measure of air density. It should not be confused with pressure height, true height or absolute height. It should not be used as an altitude reference, but as a determining criterion for the performance of an aircraft. Air density decreases with altitude. As the density of the air decreases, the density height increases. Other effects of high temperatures and high humidity are cumulative, resulting in increased elevation density. The high density reduces all the performance parameters of the aircraft. For the pilot, this means that normal power is reduced, propeller efficiency is reduced, and higher actual speed is required to maintain the aircraft during its operating parameters. This means increased requirements for track length and a reduced rate of climb. For example, a small medium aircraft that takes 1,000 feet to take off at sea level in standard atmospheric conditions requires a take-off roll of about 2,000 feet at an operational altitude of 5,000 feet. VFR flight operations can be conducted at night in mountainous terrain using judgment and common sense. Correct pre-flight planning, overall consideration of wind and weather, knowledge of the terrain and experience of the pilot in mountain flight are prerequisites for flight safety.

Constant visual contact with surface and obstacles is a major problem, and aerial operations under overcast skies or near clouds should be approached with extreme caution. “Area forecasts cover VFR clouds and weather conditions, so the warning warns that Airmet Sierra should be referenced for IFR conditions and mountain darkening,” explains Chapter 12 of Pilot`s Handbook of Aeronautical Knowledge. One. Your first flying experience over mountainous terrain (especially if you`ve spent most of your flight time over the Midwestern plains) could be an unforgettable nightmare if you don`t plan properly and aren`t aware of the potential dangers. These known cross-section lines are not present in the mountains; These flat, flat fields for forced landings are virtually non-existent; sudden changes in wind direction and speed occur; Strong updrafts and downdrafts are common, especially near or over sudden changes in terrain such as cliffs or rugged areas; Even clouds look different and can build up at incredible speed. Mountain flying should not be dangerous if you follow the recommendations below. 1. In the event of a landing outside the airport, the pilots used a number of different visual cues to obtain a reference. Use everything you need to create the contrast you need. Natural references seem to work best (trees, rocks, snow ribs, etc.) So far, an optimistic briefing – but under what conditions can we expect on the high and hilly terrain along the road? Is it possible that some of the higher ground can be hidden? Note that the minimum altitude for IFR operations along much of Victor 448, the Victor Airway, which is essentially the same as your VFR route, is 13,000 feet (or 10,000 feet for RNAV-equipped aircraft). 3. So what should a pilot do if all visual references are lost? One.

Precipitation statics are caused by aircraft coming into contact with uncharged particles in flight. These particles can be rain, snow, fog, sleet, hail, volcanic ash, dust; solid or liquid particles. When the aircraft encounters these neutral particles, the positive element of the particle is reflected away from the aircraft and the negative particle adheres to the skin of the aircraft. In a very short time, a significant negative charge will develop on the skin of the aircraft. If the aircraft is not equipped with static dischargers or has an ineffective static discharge system, the aircraft may switch to “CORONA” when a sufficient negative voltage level is reached. That is, it discharges static electricity from the ends of the aircraft, such as the wingtips, horizontal stabilizer, vertical stabilizer, antenna, propeller tips, etc. This discharge of static electricity is what you will hear in your headphones and what we call P-static. c. Do not fly a light aeroplane if the winds at altitude at the proposed altitude exceed 35 miles per hour.

Expect the winds on the mountain passes to be much faster than a few kilometers reported by them. Approach mountain passes with as much altitude as possible. Winds of 1,500 to 2,000 feet per minute are not uncommon on the leeward side. It is precisely this scenario (and similar scenarios with low ceilings and visibility) that has cost thousands of lives in aviation history. There is only one way out of this scenario. This is a flight in reference to the instruments to recover from an unusual situation and turn around to a better time. The best solution to this problem is to avoid such a situation in the first place. If it looks bad at the front, it is. You don`t need to “take a look.” Come back early, once you think a return might be an option, it`s time to do it. Work with your instructor to identify situations and predictions that may lead you to such a situation. Hover over the legal minimum VFR values with a large margin of safety to avoid becoming a statistic. Can anyone shed some light on the rubric they use to explain this? Does it just say, “Hey VFR pilots, you shouldn`t go into a cloud in the first place, but the clouds in that region might have solid cores because the highest elevation in that quartile is equal to or above the broken cloud floor”? Or is it more specific than that? Taking a look at it is an age-old practice and it shouldn`t surprise us if someone goes a little too far.

Hopefully they leave with a new respect for what it`s like to be in marginal or worse conditions without good options. But it also goes the other way. A lack of discipline can convince us that it won`t be so bad, or that seaworthy weather between departure and destination airports means that what`s in the middle can`t be so dangerous. Cloud top data for the region was estimated at about 9,000 feet of msl. One Airmet was issued for darkening mountains at the scene and at the time of the accident, while a second Airmet required nearby IFR conditions. The NTSB report does not specify whether and how the accident pilot received weather information prior to flight. 3. When approaching a ridge on the leeward side, it is recommended to approach the ridge at an angle of about 45 degrees to the horizontal direction of the ridge.

This allows for safer recoil from the rear with less stress on the aircraft during heavy turbulence and downdraft. In the event of severe turbulence, simultaneously reduce power and adjust the slope until the aircraft approaches manoeuvring speed, then adjust the power and attitude to maintain the manoeuvring speed and move away from the turbulent zone. I don`t want to bend the rules or push the boundaries here. My goal is to be old and not brave. It is rather that I am embarrassed by the vagueness of the explanation; I want to understand, on a more fundamental level, what is the shell of the weather that is part of the “darkening of the mountain”. ForeFlight lives in southeast Washington and often portrays large parts of the mountainous terrain to the east as IFR “mountain obscuration.” I live at the foot of the hills, and often, when I look like this, I only see a few uneven clouds here and there. I find this category of IFR very vague/confusing. j. Mountain wave. Many pilots walk all their lives without understanding what a mountain wave is. A number of them lost their lives because of this lack of understanding. You don`t need to be a licensed meteorologist to understand the phenomenon of mountain waves.

On October 1, 2017, at approximately 1043 Pacific Time, a Cirrus Design Corp. SR22 was destroyed when it struck terrain while maneuvering in a remote mountainous area near Klamath Falls, Oregon.