A United Airlines Boeing 737 en route from Denver to Los Angeles was forced to divert to Salt Lake City last Thursday after pilots discovered a crack in one layer of the cockpit windshield. The National Transportation Safety Board (NTSB) is investigating the incident and has sent the damaged windshield to its lab for analysis.
The crack did not compromise safety, as the multi-layer windshield design allows continued operation if one layer is damaged. Investigators are examining whether the plane was struck mid-flight, and the crew will be interviewed as part of the probe.
John Dean, CEO of WindBorne Systems, a California-based weather balloon company, said it was likely one of their balloons that hit the aircraft. The company, which operates long-duration lightweight weather balloons used for global meteorological data collection, has provided a preliminary report to the NTSB and FAA and is cooperating with authorities.
WindBorne has since implemented a software update to reduce balloon activity at commercial flight altitudes.
The flight, carrying 134 passengers and six crew members, landed safely, and passengers were later flown to Los Angeles on another aircraft.
The investigation continues amid a partial government shutdown affecting NTSB and FAA communications staff.