Challenger 300 near collision with a glider near Basel, 2019

Final reportAirproxClass D airspace

The short version

A glider pilot on a cross-country flight from the Vosges to Germany flew about 20 minutes inside Basel class D airspace without talking to anyone and without his transponder on. At 4,600 ft the Challenger 300, descending on vectors for the runway 15 ILS, met him in his left-hand spiral. Neither TCAS nor ATC knew he was there. The first officer saw him in time for the captain to bank away at 45°.

What happened

  1. About this time the glider takes off from Sarrebourg-Buhl in Moselle for Leutkirch in Germany, with a passenger in the rear seat. The pilot files no flight plan.

  2. About this time HB-JGQ takes off from Zurich on a positioning flight to Basel-Mulhouse. The glider reaches its highest point, about 6,200 ft, near Munster.

  3. About this time the glider enters Basel TMA 3 at about 5,200 ft. It makes no radio contact and the controllers do not know it is there.

  4. The Challenger descends through 4,600 ft in a left turn at 210 kt. The first officer, pilot monitoring, sees the glider flying left-hand spirals nearby and warns the captain.

  5. The captain disconnects the autopilot, banks to 45° and increases the rate of descent. The recorded data put the loss of separation at 12:20:40.

  6. The Challenger continues the ILS and lands on runway 15.

  7. About this time the glider leaves TMA 3 at about 3,900 ft and crosses the border. It lands at Leutkirch at 1720.

All times are UTC. Local time was UTC+2.

The Challenger crew judged the glider to be less than 30 m away sideways and about 1 m vertically. The glider pilot put it at 70 to 100 m sideways, and believed he was at about 800 m. The glider's data, taken from the Open Glider Network because the pilot had not saved his FLARM log, showed about 2,000 ft more than he thought he had, both near Munster and at the moment of the conflict. He could not explain the difference. The BEA could not confirm either the vertical or the horizontal distance.1

Visibility was more than 10 km, the wind light. TMA 3 runs from 3,000 ft QNH to FL 145 and is class D, where two-way radio contact is mandatory.1

Why it happened

  1. The BEA describes the sequence this way. The glider pilot entered Basel TMA 3 and flew in it for about 20 minutes without radio contact and without activating his transponder. In a left turn at 4,600 ft, his path conflicted with the Challenger being vectored to Basel-Mulhouse. With the transponder off, the Challenger's TCAS could not detect the glider. Without radio contact, the controllers did not know he was there and could not ask him to switch it on.1

  2. The glider had a Mode S transponder and a FLARM unit. The pilot could not remember which transponder mode he had selected and said he switched it on whenever it was needed. TCAS detects only aircraft whose transponder is set to report altitude. The pilot knew the area, had flown cross-border from Sarrebourg before and had current charts.1

  3. The BEA lists two contributing factors. The glider pilot entered the class D TMA without radio contact. The transponder was not on in class D airspace where the French civil aviation authority (DGAC) had not made its use mandatory. The European SERA rules allow that choice.1

  4. The BEA also names one factor that limited the outcome: the Challenger crew's lookout during the approach let them avoid a collision. The report says the event shows the value of looking outside even under IFR, and above all the benefit of using a transponder on every flight.1

The report makes no formal safety recommendations. It mentions DSAC airspace posters on radio contact and transponder use in class D, a DGAC "Be seen, see and avoid" symposium in November 2018, and a planned update of the French order on transponder carriage.1

What a crew can take from it

  1. Class D does not mean every aircraft is talking to ATC. The controllers here had no idea the glider was there. A traffic-free frequency and a quiet TCAS told the crew nothing about him. In class D below FL 145 on a good soaring day, expect gliders the controller cannot see.

  2. TCAS only sees transponders that are switched on. The glider had a Mode S transponder fitted. It was not on, so TCAS showed nothing. A blank TCAS display near soaring country is not proof the sky is empty.

  3. The crew's lookout prevented the collision. The first officer, as pilot monitoring, saw the glider during a descending turn on radar vectors and warned the captain. The captain disconnected the autopilot, banked to 45° and increased the descent. The BEA says the event shows the importance of looking outside even under IFR.

  4. The glider was higher than its pilot believed. He thought he was below TMA 3 and saw no need to call. The recorded data put him about 2,000 ft higher than he believed. The BEA's main point is the benefit of using a transponder on every flight, so that TCAS can detect the aircraft.

Study it on the course

Sources

  1. Bureau d'Enquêtes et d'Analyses (BEA). Safety investigation report BEA2019-0259, serious incident between the Bombardier Challenger 300 HB-JGQ and the Schempp-Hirth Nimbus 3DM D-KPHJ, 23 May 2019, at Bâle-Mulhouse. English courtesy translation. Published February 2023.
  2. BEA, investigation page.
  3. AIN, Report Details Harrowing Bizjet/Glider Close Encounter, 11 June 2019.

Last updated 22 October 2026

For study only. Always use the approved AFM, QRH and operator procedures.