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## Winds 

<img src='content_image/531728.jpg'>

attempted if the winds aloft forecast at mountain top levels are greater than 25 knots. Above this level, potentially dangerous tur› bulence, as well as very strong up and down drafts are likely. 

## IFR and Night Mountain Flights 

Experienced mountain pilots recommend that IFR and night flight in the mountains not be attempted. Instrument approaches and departure procedures require a highly skilled pilot and a very high performance airplane. Night obviously obscures most visual navi› gation cues. making terrain clearance difficult or impossible. 

## Weather Factors 

## Density Altitude 

From your basic flight training, you probably remember that densi› ty altitude is the pressure altitude corrected for temperature. Since increasing temperature makes the air less dense, an airplane will perform as if it is at a higher altitude than on a colder day, given that the airplane is at the same height above sea level. 

You should also remember that the standard lapse rate (the rate at which temperature normally decreases with increasing altitude in unsaturated air) compounds the problem somewhat. At sea level, the standard temperature is 59 degrees Fahrenheit, however, at 10,000 feet MSL, the standard temperature is only 23 degrees. This means that at Leadville, Colorado (elevation 9,927 feet) when the temperature is only 24 degrees, the density altitude is already above the field elevation. We will discuss density altitude in more detail later. 

## Winds Aloft Reports 

The winds aloft reports are very important to your mountain flight planning process. You should pay close attention to the forecasts at and above the mountain ridges of the terre in you will be flying into. In the west, that usually means the 9,000 and 12.000 foot fore› casts. In the east, you will look at lower winds. Winds above 25 knots at these levels should be a warning sign that should cause you to think about delaying your trip. 

Strong winds can cause some of the most dangerous conditions you’ll have to contend with in the moun› tains. To ininimize the chance. of encountering danger› ous turbulence, mountain flying should not be 

