Flying with friends: Make GPS show friends position?

Hey everybody,
I really enjoy the game and love flying around with my friends, but one thing keeps annoying me when flying with friends. Its that my friend doesnt show up on my GPS system and i dont show up for him. We can spot each other in the air its just very difficult as you all may know. Is there a way to make friends show up on the GPS? At the moment only the traffic is visible for me.
Thanks for your time and help,