Look at a file called shpfile.txt in your terrain editor directory.
It filters out any object you don't want on to appear within the editor.
If you want a plane that doesn't appear on the list, go remove it from that file.
I suggest making a backup of the original file first though.
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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"