Sorry to hear about your friend.
If you are in the UK, you will need an exemption from Article 129 and the permission of the landowner.
Exemptions for scattering of ashes are free of charge, and can be obtained from the CAA, by calling this number: 01293 573525.
I have found the best way of doing this without getting yourself, and the inside of the aircraft covered in ashes, is to use one of those cardboard tubes of about 4''-6'' diameter in which charts/posters are often posted.
The ashes are then inserted in one end of the tube, contained in a strong paper bag. The other end of the tube is then pushed out into the airflow through a partly open door, or window. At the appropriate moment, the paper bag is punctured, and the ashes are sucked out of the tube by the airflow, and carried away from the aircraft.
Two tips though; 1. Make sure you have a firm hold on the tube, or secure it in some way, so that you don't drop the whole thing. 2. Make sure you have a reliable way of breaking the paper bag.
MJ
