Had to organise a similar event as part of a secondary duty in the RAF. Ashes were dispensed only to stick to the side of the aircraft despite use of max sideslip. Pilot diverted to nearby airfield for a quick 'hosedown' before RTB to greet funeral party and grieving family.
The majority of the deceased ended up going down the drains rather than being dispersed over the countryside he loved.
Similar stories of people who have been 'buried at sea' via sonar buoy dropped by a Nimrod have also lead to disaster.
A request that should be handled with discretion IMHO.
(Names and places omitted to protect the innocent!)