On 15 October 2017, a Falcon 2000EX on base leg for an easterly ILS approach at St Gallen-Altenrhein came into close proximity with a reciprocal track glider at 5000 feet QNH in Class E' airspace in day VMC with neither aircraft seeing the other until just before their minimum separation - 0.35 nm horizontally and 131 feet vertically - occurred. The Investigation attributed the conflict to the lack of relevant traffic separation requirements in Class E airspace and to the glider not having its transponder switched on and not listening out with the relevant ATC Unit.