Why did the pilot make the call less than 20 minutes from the private plane's original destination of Bozeman, Mont.? The investigation 'begins with that question,' a federal official says. The investigation to unravel the cause of the plane crash that killed 14 Californians en route to a Montana ski trip focused Tuesday on the central mystery of the flight: Why did the pilot, not far from his destination in Bozeman, Mont., suddenly change his mind and attempt the fateful landing in Butte?