A United Airlines plane appears to have collided with a weather balloon while cruising over Utah at 36,000 feet last week, fracturing layers of its windshield and forcing an emergency landing.

A California company called Windborne Systems said it started looking into the situation Sunday, not long after the National Transportation Safety Board said it was investigating. Windborne quickly concluded that the Boeing 737 Max very likely ran into one of its balloons, despite the company's best efforts to prevent such collisions.

The plane, which was flying from Denver to Los Angeles, did not lose cabin pressure and landed safely in Salt Lake City last Thursday. United said 134 passengers and six crew members were aboard.

Windborne CEO John Dean said he was surprised at the extent of the

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