WASHINGTON – The Germanwings air crash investigation shouldn’t set a precedent for future investigations because it sought to assign blame before the probe was complete, which could jeopardize airline co-operation if it became the practice, the head of a trade association representing the global airline industry said Wednesday.

Airlines and aviation safety regulators around the world have long-established procedures for investigating crashes that put identifying and correcting safety risks ahead of assigning blame, Tony Tyler, the CEO and director general of the International Air Transport Association, told reporters. Investigating with the intent to punish risks a loss of transparency and openness, he said.

French prosecutors revealed within days of the crash that the plane’s cockpit voice recording indicated that one of the pilots deliberately flew the plane into a mountainside, killing all 150 people on board. The subsequent investigation has focused in large part on the pilot’s history of depression and procedures at Germanwings and its parent company, Lufthansa, for screening pilots for mental health issues.

“The circumstances of investigation of the Germanwings accident have been highly unusual, and something that began as an accident investigation morphed into highly public criminal investigation in which it seemed that every day new revelations were coming out,” Tyler said. “This is a truly extraordinary case in many ways, but it shouldn’t set a precedent for the future.”

The Paris prosecutor’s office said last week it is looking into claims that information from the investigation was wrongly leaked to the media. The move came after a lawsuit was filed by France’s leading pilots union, SNPL, over leaks about the crash investigation. The union is claiming a violation of French law about keeping information about investigations secret while they are ongoing.

“I’m not going say that they anyone’s done anything wrong, but the important principle to bear in mind is that accident investigations should be conducted on a non-punitive basis,” Tyler said. “When you have the possibility of punitive measures resulting from accident investigation you then start to introduce unhelpful dynamics into the whole process where you risk losing the transparency, the openness” that’s needed “to identify what caused the event.”