CLoD surface wind reports

[Baffin]

With the new Cliffs of Dover Blitz well established, it helps to review a few basics. Surface wind reporting for taxi and takeoff planning continues to have a few glitches, but it works if you know what it says.

Wind direction in aviation is always reported relative to the direction from which the wind is blowing. e.g. A warm, south wind is 180° and that cold, north wind is 360°. Winds reported by a control tower or other airfield control agency are expressed in degrees MAGNETIC. All winds reported by enroute control agencies are expressed as degrees TRUE. To clarify the reasons for the difference, consider that all runways are marked and numbered by magnetic heading so the departing pilot can check his heading instrument when lining up for takeoff. The pilot enroute between two points uses charts that are plotted by reference to TRUE North. The chart has magnetic variation somewhere hidden in all those lines and numbers, but basic courses are always TRUE. Inflight, the pilot does not need to be juggling +West/-East numbers. Navigators can do that, or pilots SHOULD HAVE during flight planning on the ground.

Wind speed (Velocity) is commonly expressed as (Nautical or Statute) Miles/hour or Kilometers/hour, depending on location and historical date. MPH was the RAF Standard. KPH was used by the axis. Let's forget about knots...

So, a standard 1940 RAF Wind notation might look like: "Wind 270/5". (Wind from the West at 5 MPH).

BUT, CLoD doesn't quite do it that way.
When the Clod weatherman reports "90 2", what he meant to say is "270/5" or 270° at about 5 MPH.

TAB 7 3 - In our simulator, this keyboard command requests the surface wind from the tower or other controlling agency. The report output however, is not consistent with the standard explained above. Instead of "180/4" (180° at Four MPH), this south wind in CLoD will be reported as "360 2".

The original CLoD programmers used wind direction backwards from the accepted norm, and chose to express wind velocity in meters per second. It's another special "Feature", held over from prior versions. Do not despair, the conversion to "Ops Normal" is a simple one.

On the compass rose, simply look at the opposite side of the circle to find the proper direction that falls between 0° and 360°. With no compass rose available, just add 180° to the reported wind direction, unless that sum is greater than 360°. If that's the case, go back and subtract 180° instead. For example:

090° (East) reported by CLoD + 180° correction = 270° (West). That's the direction to use.

270° (West) reported by CLoD + 180° correction = 450°. (Too much. Greater than 360!) ...so try the subtraction fix:
270° (West) reported by CLoD - 180° correction = 090°. (East). That's where the wind is really coming from.

With the direction corrected, we move on to the wind speed correction, which is very straight forward:

1 Meter/Second = 2.23694 Miles per Hour. I simplify this by considering 1 M/s - 2¼ MPH.

Therefore, drawing on our vast mathematical data banks, 2 m/s = 4½ mph, 3 m/s ≈ 7 mph, 4 m/s ≈ 9 mph, etc.

Finally, when the Clod weatherman reports "90 2", what he meant to say is "270/5" or 270° at about 5 MPH.