Originally Posted by
Bell_ringer
Doesn't make much sense how two aircraft leaving the same base and with a converging routing wouldn't be aware of the other.
You seem to be assuming that both aircraft were flying pre-planned routes. As one was apparently a school aircraft, it could well have been doing training manoeuvres in uncontrolled airspace. I learned to fly at Wycombe Air Park and have had that sort of session in that area. Safety depends on continual observation at all times, which can be quite difficult if you're concentrating on flying an unfamiliar manoeuvre or observing your student doing so, and if there is no TCAS or other aids to help you.