Emergency services were called to reports of a collision north-east of Drymen, Stirling, around 4.45pm on Friday.
Police Scotland said an 80-year-old man and a 16-year-old boy were pronounced dead at the scene.
Their next of kin have been informed.
Temporary airspace restrictions, including drones, are in place over the Drymen area, following the crash.
These are likely to be in place to allow the Air Accidents Investigation Branch to investigate, police said.
Officers have warned it is a criminal offence to fly in restricted airspace.
