Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: We know that Germanwings Flight 4U 9525 was flown into a mountain by co-pilot Andreas Lubitz, 27, after he locked the plane's pilot out of the cockpit.

Germanwings crash leaves unanswered questions