Reference: Aviation Simulation WX Tutorial

Adding real weather conditions to your flying experience increases the interest and challenge of simulation. There are several ways to do this and we will explain how to do this at the end of this lesson.

First, we'll focus on those aspects of weather relevant to flight simulation in Microsoft Flight Simulator.

Nice WX

Photo courtesy Paul Dopson

Weather Phenomena: Surface winds are of particular interest to the pilot and have a significant effect on takeoff and landing operations. Winds are reported in terms of the magnetic direction they are blowing from and their strength in knots. Winds that are 270 at 10 would indicate 10 knot winds blowing from the west.

With surface winds above five knots it is desirable to takeoff and land into the wind. Since we know air movement over and under the wings generates lift a headwind will contribute to this while a tailwind reduces effective lift.

A good headwind reduces the distance required for takeoff and landing while a tailwind increases the distance requirement. Active runways are determined by the current surface wind conditions.

Winds aloft are of interest for fuel efficiency and time of arrival. A headwind slows progress and burns more fuel and obviously a tailwind moves you faster to your destination while burning less fuel. These are of little importance to the simulator pilot.

Clouds in the simulator are more of interest for their beauty than anything else. Of course if you are flying VFR you must stay clear of the clouds so in planning your flight you should evaluate the weather both at your departure and destination airports to determine if you are flying VFR or IFR. Read here for more information on clouds.

Visibility is also of interest in determining whether your flight will be VFR or IFR. In addition to clouds, fog, haze, smoke and precipitation will reduce visibility.

Nice WXThunderstorms are to be avoided at all costs in the real world, but are rather fun in the simulator. Thunder and lightning is well modeled in FS2002 and there is little danger. It is possible to experience severe turbulence in a thunderstorm as seen by erratic and continuous airspeed and altitude changes.

Pressure Altitude: Barometric pressure is quite important. Altitude measurement and reporting is wholly dependent on air pressure. Since the altimeter uses air pressure directly to infer altitude, setting the altimeter according to the local barometric pressure is critical for accurate altitude reporting. Fortunately this is easy in the simulator. Pressing the “B” key automatically sets local pressure. Not having that luxury in the real world, altimeters are always set to local readings according to ATIS or controller reports. There is a knob on the altimeter for this purpose.

In the US flying above 18,000 feet puts us into class A airspace and flight levels. This is known as the transition altitude and all altitudes above that are referred to as flight levels (FL190, FL200, etc.). The altimeter is set to a standard 29.92 inches of mercury (1013 millibars) when passing FL180. This is known as measuring altitude relative to a standard datum plane and is done to assure aircraft are using a common standard when flying above where actual barometric pressure can effectively be measured. Other countries use different altitudes for this transition level.

Density Altitude: A standard day is sea level, 59 degrees Fahrenheit and pressure of 29.92 and performance figures listed in the aircraft manual are based on this standard day. Your climb performance will vary based on actual conditions at time of takeoff particularly if you are departing at a high-altitude airport and a combination with the weather (WX) could be such that your actual performance will fail to meet levels necessary achieve flight with disastrous results.

A pilot must understand density altitude and its effect on performance. This article by Hal Stoen explains density altitude and gives an example of what can happen when it is not accounted for.

So how is the current weather obtained? It depends how you set it in the simulator. Using the World/Weather menu, you can manually set the WX any way you want. But it won’t change until you manually reset it again.

A little better than setting it manually is to use the Real Weather option from the same menu. This downloads real-world, real-time weather, but only for one station at a time at it doesn’t automatically refresh. You have to reload it every time you fly to a new area or every hour or so.

Exercise: Load the Cessna 182S and go to KLGB. From the World menu, select Weather and choose the Real World Weather option. After the WX loads, press OK and you return to the simulator. Make sure the ATC is turned on (see the ATC Lesson Seven for instructions), bring up the ATC panel and select “Tune ATIS on 127.750.” ATIS stands for Automatic Traffic Information System and is a recorded report for the airport that provides current winds, clouds and visibility, active runways and other information. This saves the controllers from having to repeat this to pilots and saves radio airtime. Pilots should always have the current ATIS before contacting a controller for departure or approach clearance. Recordings are named by the alphabet and change hourly. If current information is Hotel, then Golf has expired, and the next cycle will be India.

Tune the ATIS and listen and read the recording that scrolls across the screen. Write down the identifier (so you can tell the controller you have “Tango,” or whatever the current ATIS is), the altimeter, winds and active runway. Note other information given.

Other ways to obtain WX include purchasing the utility FSMeteo. For $15 US it automatically refreshes the WX every five minutes and as you move from area to area. Additional features include the ability to smooth WX changes between two areas so that the change is not abrupt (recommended).

Lastly, flying online at VATSIM and using Squawkbox software (free) will load near-real time WX. There is a feature called ACARS which returns weather for most airports in the world but you need to be instrument certified at Altair before flying online and that is the subject of the next training module: Instrument Flying.

Half a plane

Photo courtesy Bob Harrington

How to read METAR reports: ACARS and other utilities return weather in the form of a METAR. This is an international standard Aviation Routine Weather Report and is available for most US airports and many airports world-wide.

Exercise: At the bottom of the METAR tutorial, put KLGB in for the airport and obtain a current METAR. Write down and decode weather from this report.


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