IFR Mooney passes close over a circling Duo Discus

An IFR Mooney on approach and a Duo Discus circling in lift passed within about 115 m horizontally and 175 m vertically; both crews saw each other and no one was hurt. Configuring for the approach head-down, the Mooney pilot was not expecting VFR traffic near the approach path and got no traffic information. The two-pilot glider was circling in good lift, unaware the instrument approach point lay there — a detail no longer shown on VFR charts. Its transponder was sending no altitude, so it showed on radar without height and triggered no alert, and the two warning systems were incompatible — Flarm on the glider, none on the Mooney.

1. Glider circling in lift (VFR): A two-pilot Duo Discus on a VFR cross-country was circling in good lift near Langenthal, unaware that an instrument approach path crossed there.
2. Mooney inbound on IFR approach: A Mooney was configuring for its instrument approach to a nearby airfield in a head-down phase, not expecting VFR traffic near the approach axis.
3. Glider sending no altitude: The glider's transponder was set so it sent no altitude, so it showed on radar without height; ATC could give no traffic information and no automatic alert could trigger.
4. Paths cross at ~1,830 m MSL: The two aircraft crossed at about 1,830 m MSL, closing to roughly 115 m horizontally and 175 m vertically; their collision-warning systems were incompatible.
5. Seen in time, no evasion needed: In good visibility the Mooney pilot saw the glider and judged no avoiding action necessary; the two aircraft passed with no injury or damage.