The potential hazard of IFR flight in Class "E" airspace
16 May 2016
On 3 September 2014 in Class 'E' airspace, a light aircraft carrying out a spin recovery exercise in day VMC came very close to an aircraft climbing out of Sault Ste. Marie. Although the crew had seen the light aircraft ahead and above and temporarily levelled off, the light aircraft then began "a rapid descending turn" and a TCAS RA 'Descend' followed. It was judged that a turn would also be necessary but even with this, the two aircraft subsequently passed within 350-450 feet at the same altitude in opposite directions.
Source Skybrary