According to reports, the flight from Paris arrived over Ajaccio on Tuesday and attempted to make contact with the control tower. Instead of the usual landing clearance? Radio silence. The plane had to remain in the air for a tense 18 minutes while pilots repeatedly tried to reach the tower. Eventually, the controller reportedly woke up, and the aircraft was able to land safely. But prosecutors aren’t shrugging this one off. The investigation was opened for “endangering the lives of others,” a serious charge that could mean both disciplinary and criminal consequences for the controller if the allegations hold up. Aviation authorities are now combing through what went wrong—whether this was a case of exhaustion, negligence, or something more troubling. For the 100-plus people stuck circling in the sky, though, the thought of their fate hinging on a nap has left many rattled.