U.S. aviation safety regulators are investigating claims that pilot trainees for Cathay Pacific Airways Ltd. at a U.S. flight school were involved in training mishaps that weren’t properly reported.

The U.S. Federal Aviation Administration is probing the alleged incidents, the agency said June 7, in a statement to Bloomberg. It didn’t provide additional details.

The disclosure comes after Phoenix-based AeroGuard Flight Training Center suspended all solo flights for Cathay cadets, citing incidents that damaged planes and went unreported by the trainee aircrew. AeroGuard told Cathay cadets it was grounding those flights after the school saw an “alarming increase in solo incidents” during training, according to a memo that was reported earlier by Bloomberg.

Representatives for Cathay and AeroGuard did not immediately respond to messages seeking comment. The Hong Kong-based carrier previously acknowledged that the incidents took place and said it supported the decision of the flight school.