A Condor Boeing 767-300, registration D-ABUK performing maintenance flight DE-4702 from Frankfurt/Main to Frankfurt/Main (Germany) with just crew on board, was enroute at FL360 about 160nm north of Frankfurt when the crew initiated an emergency descent to FL100 due to a defect at the windshield. The aircraft returned to Frankfurt at FL100 and landed safely about 75 minutes after departure.
On Jul 8th 2020 the airline reported (in German): "Der Flug DE4702 ist gestern aufgrund eines Defekts an der Cockpitscheibe vorzeitig wieder in Frankfurt gelandet. Es handelte sich hierbei um einen routinemäßigen technischen Überprüfungsflug des Flugzeugs. Die Boeing 767 ist nach ihrer sicheren Landung normal zur Parkposition gerollt. Die Flugtauglichkeit war zu keiner Zeit eingeschränkt." (Translation by AVH: Flight DE4702 prematurely returned to Frankfurt due to a defect at the windshield. It was a routine technical verification flight of the aircraft. The Boeing 767 landed safely and taxied to the park position. The airworthiness of the aircraft was not restricted at any time."