United Airlines flight 1093 was just 50 minutes into its trip from Denver last week when the crew reported the damage and diverted the flight to Salt Lake City.
The Boeing 737 Max 8 landed safely and no one was seriously hurt.
Passengers were eventually put on a new plane and got to L.A. about six hours late.
The National Transportation Safety Board has opened an investigation into the incident. The damaged windscreen will be sent to a lab for testing.