Originally Posted by
Richard J.
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.
Fair enough, but at some point they would have reported their position and intentions.