How can I get Mission Editor to recognize other area IE: Western Canada/Alaska?

Adding a new Operating Area is relatively simple.

Operating Areas are stored in the opareas.dat file which is located in the INFO folder.  Open the file using Notepad and get a feel for the format to follow.  To create a new Operating Area you must define the boundries and enter them in this file.

Picture a world map hanging on your wall.  An Operating Area is a box drawn around a portion of the map.  All of the airbases that fall inside this box will be included in your new Operating Area.  To make your entry you need to define two opposite corners of the box, either Northwest/Southeast or Southwest/Northeast.   Find these two spots and write down the longitude and latitude of each.

Once you have the corners defined simply give your new Operating Area a name and enter it into opareas.dat following the existing format.  For example,  you wanted to define a new area that includes the Aleutians. After you select your coordinates your new entry in the opareas.dat file might look like this:

Aleutian Islands, N58 0, E172 0, N50 0, W156 0

Save the modified opareas.dat file and open Mission Builder.  To use your new Operating Area (or Theater if you prefer), click on the "New Mission" button.  In the pop-up window click on  "Operating Area" select the new one you created then click on "Apply".  When the scenery loads, click on "Airbase" and all of the runways that are entered into the airbases.dat file that fall within your new area will appear on the menu for use.

If two or more Operating Area overlap it is not a problem.  Sometimes it's an advantage to have the same runway appear in multiple Operating Areas, especially when desigining missions that take place close to the edge of an area.

You will find a good map or globe almost essential.