Investigation Update: NTSB Confirms Prior United 737 Encounter With Weather Balloon

Image credit: Gemini AI

The National Transportation Safety Board (NTSB) has concluded that a United Airlines Boeing 737-8 (United Flight 1093) struck a weather balloon while cruising at about 36,000 feet on 16 October 2025, shattering the right-side cockpit windshield and showering the flight crew with glass. The aircraft — en route from Denver to Los Angeles with 112 people on board — diverted and made a safe emergency landing in Salt Lake City; the captain sustained superficial lacerations but the rest of the crew and passengers escaped serious injury. The NTSB’s preliminary findings, released in late November, identify the object as a commercial atmospheric sounding balloon launched from Washington state and outline both the sequence of events and safety implications for high-altitude balloon operations.

What the NTSB found

According to the NTSB’s preliminary report and presentations, the collision occurred shortly before 06:45 local time while the Boeing 737-8 was cruising near Moab, Utah, at flight level 360 (about 36,000 ft.). The flight crew reported spotting an unidentified object and then experienced a loud impact; subsequent visual evidence and damage inspection showed extensive cracking of the windshield’s multiple laminated layers. Photographs released by investigators show a spiderweb of fractures on the cockpit pane, but cabin pressurization remained stable and the aircraft systems continued to function sufficiently to allow a controlled diversion. The NTSB concluded the object was consistent with a commercial weather-balloon system that had lost telemetry and drifted into the aircraft’s path.

WindBorne Systems — a company that operates long-duration Global Sounding Balloons (GSBs) — publicly said one of its balloons had been launched from the Spokane area earlier the same day and had lost contact while drifting across the western U.S. WindBorne subsequently announced operational changes intended to reduce the likelihood of similar events, including shortening balloon dwell time in commercial airspace and improving coordination with air-traffic authorities. Industry reporting indicates a mapped overlay in the investigation placed the balloon and aircraft within a narrow margin of proximity before impact.

What happened in the cockpit

Crew statements and audio (summarized in the NTSB release) describe a sudden, loud bang and an immediate inspection by the pilots showing the right-side windshield with multiple cracks and displaced fragments. The captain treated his own minor arm wounds in the cockpit and then began the planned diversion to Salt Lake City. Despite the damage, cockpit systems retained redundancy and cabin pressurization did not drop abruptly; the pilots followed emergency procedures and completed a stable, controlled descent and landing. The NTSB noted that windshield construction (laminated layers of glass and polycarbonate) likely prevented catastrophic failure, even though fragments nevertheless sprayed into the flight deck.

Why a weather balloon can be dangerous at altitude

Modern aviation windshields are certified to withstand bird strikes (typically up to a specified weight at lower altitudes) and certain debris impacts, but they are not routinely designed for high-velocity collisions with objects traveling at relative closing speeds of several hundred knots. Atmospheric research balloons are usually made to minimize rigid components; still, payload hardware, instrumentation packages, or stresses on the balloon envelope can produce hard elements or whipping lines that, at the right geometry, can impart localized force sufficient to crack multi-layered glazing. The NTSB is focusing on the balloon’s design, telemetry loss, and the launch operator’s risk mitigations as probable contributory factors.

Operational fallout and industry reaction

The incident has triggered immediate scrutiny of high-altitude balloon operations, especially the rapid growth of commercial balloon systems intended for long-duration atmospheric sensing. Regulators, airlines and launch companies are discussing more robust NOTAM (Notice to Air Missions) procedures, improved real-time tracking and automated alerts to affected air-traffic control centers. WindBorne said it will implement additional safety measures — including collision-avoidance algorithms, enhanced notification, and reducing the time a balloon spends in active commercial air routes — while the FAA and industry groups review whether more prescriptive controls are necessary.

Some carriers and insurers are reassessing risk models for operations along corridors used by long-duration balloon flights. The event has also raised questions about whether balloon operators are providing sufficiently precise and timely position data to pilots and controllers, and whether the current NOTAM framework adequately covers transient, high-altitude objects that can cross multiple flight information regions. Aviation safety analysts say this NTSB finding will almost certainly prompt changes to how operators coordinate launches and how air traffic authorities disseminate warnings to en route aircraft.

Human factors and crew performance

Investigators praised the flight crew for their calm and effective handling of the emergency. Despite being “showered with glass,” the crew maintained control, treated injuries, declared an emergency, and executed a successful diversion. The NTSB will continue to analyze crew communications, workload, and checklist use to identify lessons that could be applied in training programs for responding to sudden cockpit contamination or partial glazing failure. The agency also flagged the importance of immediate cockpit coordination and the captain’s decision-making in avoiding further risk to passengers and crew.

Regulatory and technical follow-up

The NTSB’s preliminary report stops short of assigning probable cause beyond identifying the object, but the agency will continue laboratory analysis of recovered fragments, metallurgical testing and telemetry correlation to build a full causal picture. The FAA will likely evaluate whether balloon launches should have enhanced real-time tracking and mandatory safeguards when trajectories could intersect typical cruise flight levels. Aviation stakeholders say possible steps include: mandatory live telemetry feeds to ATC, geofencing restrictions for sustained balloon operations, shorter flight-time windows in busy air corridors and additional equipment on balloons to enhance radar detectability.

Safety implications for passengers and the public

Although the event ended without loss of life, it is a wake-up call. Air-travel safety depends on anticipating and mitigating unexpected airborne hazards, whether from birds, space junk, drones, or — now evidently — commercial atmospheric balloons. For passengers, the immediate reassurance is that modern aircraft have redundant systems and certified structures that can contain damage at altitude; for policymakers and operators, the incident underlines a regulatory gap when novel airborne platforms enter commercial airspace in higher numbers. The NTSB’s final report (when published) will likely include safety recommendations that could change how balloon operations, air traffic management and aircraft certification address high-altitude collision risk.