P2006T IFR approach: two airprox with gliders in class E airspace

During an IFR training approach to Les Eplatures, a Tecnam P2006T had two close encounters with gliders in Class E airspace; no injuries and no damage resulted. About 45 gliders were on cross-country along the Jura that day under building cumulus. At 14:59 the P2006T and an ASH 26 E passed at 185 m horizontal and 375 ft on opposite headings (airprox Cat B). At 15:06 it passed 60 m horizontal and 50 ft above an SZD-55-1; the glider pilot, alerted by FLARM, evaded (Cat A, near-collision). Traffic advisories were given, but separation is not mandatory in Class E and the cumulus limited what ATC could provide.

1. IFR training approach to Les Eplatures: Tecnam P2006T (HB-LBU), twin-engine 4-seat trainer, on an IFR training flight from Speck-Fehraltorf (LSZK) to Les Eplatures (LSGC). Crew: instructor (born 1951, ATPL, 18,080 h total, 68 h on type) and 2 students. PIC was a student acquiring IR rating; took off 13:45 from LSZK, switched from VFR to IFR at FL90 toward Les Eplatures. Plan: training approach to runway 24 with tailwind, missed approach + go-around, then IFR approach + landing on runway 06. Equipment: Garrecht TRX-1500 collision warning with ADS-B + transponder receiver + integrated FLARM; Mode-S transponder (no GPS output).
2. Class E: traffic advisories only: The events occurred in class E airspace outside the Les Eplatures control zone, where ATC may provide traffic advisories but separation between IFR and VFR traffic is not mandatory. Pilots are responsible for see-and-avoid.
3. Active XC glider day, ~45 along Jura: The day's sailplane weather forecast had been very promising. ~45 gliders were doing cross-country flights along the Jura on 21 May 2023, including the two involved gliders: ASH 26 E (HB-2283, launched 11:37 from Dittingen) and SZD-55-1 (HB-3118, launched ~20 min later from Grenchen). Both had PowerFLARM Fusion with ADS-B + FLARM and Mode-S transponders; both had canopy strobes. ASH 26 E pilot stated his airborne FLARM gave no warning during the entire flight.
4. Building cumulus reducing visibility: From 14:20 cumulus build-up; by 14:50 the sky was 5/8 to 7/8 with cumulus tops climbing, base ~2,150 m M (7,100 ft AMSL). The P2006T was operating partly in and partly out of clouds during its IFR procedure. Sun azimuth 222°, elevation 57°. Visibility 10-15 km. Light SE wind.
5. First airprox: 185 m / 375 ft, Cat B: At 14:59:54 the P2006T (climbing on missed approach outbound leg of holding pattern at 7,000 ft AMSL) and the ASH 26 E (overflying north of Les Eplatures CTR at 7,200 ft AMSL) crossed on near-opposite headings at horizontal 0.1 NM (185 m) and vertical 375 ft. The P2006T crew saw the glider 100 ft below on their right; a crew member commented 'it's strange that we have glider traffic.' The ASH 26 E pilot stated FLARM gave no warning. ICAO airprox Cat B (safety could have been affected).
6. ATC traffic advisories repeated: Between 14:45 and 15:06 the Alps Radar controller had given multiple traffic advisories to the P2006T about gliders in/near its approach path. STCA (Short Term Conflict Alert) generated warnings from 14:55:39 onward. At 15:05:47 a final advisory pointed out a glider 700 ft below in climb.
7. Second airprox: 60 m / 50 ft, Cat A: At 15:06:58 the P2006T passed 60 m horizontally and 50 ft above the SZD-55-1 (which had just exited the CTR at 6,900 ft AMSL descending southwestward). The glider pilot had seen an aircraft return on the PowerFLARM ring display (no direction/relative-height information for non-GPS Mode-S returns) ~2 NM out and shrinking; warned of an IFR aircraft by ATC, the pilot flew an avoidance maneuver. The P2006T student emerging from cloud saw the glider ~100 m away, ~20 m lower, with strobes flashing and already evading; he kept course. ICAO airprox Cat A (serious risk of collision).
8. Glider evaded, both continued, no damage: Both gliders continued to their destinations. P2006T completed its IFR approach to runway 06 without further incident. No damage; no injuries. SUST causal analysis: the pilots did not perceive each other's aircraft in time. Contributing factors: (1) the IFR procedure was being flown in class E airspace where ATC's ability to ensure separation is limited; (2) the building cumulus cloud situation made visual recognition of other aircraft more difficult. SUST issued one safety notice on sensitising airspace users around Les Eplatures.