[QUOTE=vibrex;26536027]
Originally Posted by
Worcester
Could well be, the temperature overnight seems low enough, but don't they normally only deice just before takeoff?/QUOTE]
Yes they do and it will be all around the aircraft too. Sounds more like oil and crud from around the APU to me. Old/used Skydrol can go a green colour too.
That's untrue.
Aircraft are anti iced overnight when a frost is expected as a preventative measure.