History of the Flight
On 23 May 2019, at approximately 12:20 UTC, a Challenger 300 (registration HB-JGQ) operated by Premium Jet AG was descending for an ILS approach to runway 15 at Bâle-Mulhouse airport. The crew consisted of a captain (pilot flying) and a co-pilot (pilot monitoring). Simultaneously, a Schempp Hirth HS-5 Nimbus 3DM glider (registration D-KPHJ), piloted by a private pilot with a passenger, was en route from Sarrebourg-Buhl to Leutkirch, Germany.
While the Challenger was descending through 4,600 ft in the Basel TMA (Class D) in a left turn at 210 kt, the pilot monitoring spotted the glider in left-hand spirals nearby. The pilot flying disconnected the autopilot and executed an evasive maneuver, banking to 45° and increasing descent rate. The crew estimated the lateral separation at less than 30 m and vertical separation at 1 m. The glider was not detected by the Challenger's TCAS or other onboard systems, and air traffic controllers were unaware of the glider's presence in the airspace.
The Challenger continued its approach and landed without further incident at 12:27. The glider pilot continued, crossed the German border at 12:35, and landed at his destination at 17:20.
Pilot Information
The captain, aged 48, held an ATPL(A) with 8,507 total flight hours, including 156 hours on type. The co-pilot, aged 35, held a CPL(A) with 1,837 total hours, including 367 hours on type. The glider pilot, aged 48, held a Sailplane Pilot Licence with 1,491 flight hours, 803 hours on type. He stated that he was aware of the TMA but believed he was flying below it, so he did not make radio contact. He could not recall the transponder mode selected but stated he switched it on when necessary. He did not file a flight plan for the border crossing, believing it was not mandatory for gliders.
Aircraft Equipment
The Challenger 300 was equipped with a TCAS capable of detecting aircraft with transponders set to ALT. The glider had a Mode S transponder and a GNSS LX Navigation 7000 with FLARM for collision avoidance. The glider's engine was retracted at the time.
Meteorological Conditions
Météo-France reported visibility greater than 10 km, broken clouds at 8,000 m, temperature 20°C, QNH 1018. Winds were light: northerly surface wind 4–7 kt, easterly 5–10 kt between 2,000 and 5,000 ft, calm at 10,000 ft.
Recorded Data
FDR data from the Challenger and OGN data from the glider (FLARM data not saved) were analyzed. The glider's maximum altitude near Munster was about 6,200 ft, higher than the pilot's estimate. The glider entered Basel TMA 3 at around 12:15 at about 5,200 ft and exited at 12:35 at about 3,900 ft, remaining in Class D airspace for approximately 20 minutes without radio contact.
Regulatory Aspects
SERA regulations require continuous air-ground voice communications in Class D airspace. French regulations require transponder carriage and activation in such airspace. The glider pilot did not comply with these requirements.