There are no easy answers to increasing the "be seen" part of "see and be seen" but plastic aeroplanes can be painted colors other than white (usually ordered pre-manufacture with carbon composites).
A 1/2 second glance at each of these photos shows how contrast with background helps (Carbon Composite aircraft):
Photos: Zivko Edge 540A Aircraft Pictures | Airliners.net
compared to:
Photos: Zivko Edge 540 Aircraft Pictures | Airliners.net
Then this one: Yellow v grey sky:
http://smoke-on.com/blog/wp-content/...b-rb-00521.jpg
And From :
Black on Yellow, Best Visible Contrast
"Why yellow?
Yellow, most commonly used in highlighters is the most visible color to the human eye. The reason has to do with the wavelengths of color. Visible light ranges from red, the color with the longest wavelength, through orange, yellow, green, blue, and indigo to violet, the color with the shortest wavelength. Yellow and green are right in the middle of the spectrum's wavelengths, therefore, our eyes are most sensitive to these colors making them the easiest to see. This is even true for people who are colorblind.
For those who are colorblind, green, yellow, orange, and red are all perceived as yellow or grey. However, when the color actually viewed is yellow, the yellow appears brighter than the perceived "yellow" that is seen in place of red or green.
So if we notice yellow and green more quickly than other colors, then why are stop signs and most emergency vehicles painted red? The choice of red has more to do with tradition than visibility. Because yellow has been proven to be more visible, many communities have started to paint their fire equipment and ambulances a very bright yellowish-green, which helps motorists see them coming in which they are able to get out of their way more quickly."