Descending airliner climbs hard to avoid a thermalling ASK 21

An airliner descending under IFR passed close to an ASK 21 thermalling under VFR in Class E airspace, where IFR traffic is not separated from gliders. Its crew saw the glider only three to four seconds before a collision looked possible: they disconnected the autopilot, applied full thrust and pulled into a hard climb, passing close on one side. The glider pilot, circling with two others, had seen the jet and turned away. Estimates of the miss distance differed sharply — about 50 m horizontally and 20 m vertically, against several hundred. The glider had no transponder, which was not required, and never showed on radar; no one was hurt.

1. Airliner descending in Class E: A regional airliner was descending under IFR through Class E airspace, where instrument traffic is not separated from VFR gliders.
2. Glider invisible to ATC: A two-seat glider was thermalling under VFR with two others; it carried no transponder — not required — and did not appear on the controller's radar.
3. Glider sighted 3-4 s ahead: The airliner crew caught sight of the glider circling directly ahead only three to four seconds before they judged a collision possible.
4. Aggressive evasive climb: The pilot flying disconnected the autopilot, set full thrust and pulled into a steep climb; the glider pilot, having seen the jet, kept turning away.
5. Passed close, no contact: The aircraft passed close on one side — the crew estimated about 50 m horizontally and 20 m vertically, the glider pilot several hundred — with no injury or damage.