NTSB Reports Weather Balloon Collision with United Airlines Flight 1093

NTSB Preliminary Report: United Airlines Flight 1093 Incident Analysis

On November 20, 2025, the National Transportation Safety Board (NTSB) released its preliminary report regarding a significant mid-air incident that occurred roughly one month prior. The investigation, filed under ID DCA26LA012, addresses the events of October 16, 2025, when a United Airlines Boeing 737-8 (MAX 8) collided with an unidentified object while cruising at high altitude. For weeks, industry observers and the public speculated on the nature of the object, with theories ranging from space debris to meteors. The release of this report provides the first official clarity on the matter.

The incident involved United Airlines Flight 1093, which was operating a scheduled domestic passenger flight from Denver International Airport (DEN) to Los Angeles International Airport (LAX). While flying over Utah, the aircraft suffered substantial damage to the flight deck windshield, forcing an emergency diversion. The release of the preliminary report marks a critical step in understanding how high-altitude airspace is managed and the potential risks posed by unmanned free balloons.

We have analyzed the NTSB’s findings to break down the sequence of events, the identification of the object involved, and the structural performance of the aircraft during the emergency. This report relies strictly on the factual data provided by the NTSB and the investigative research desk to offer a comprehensive overview of the event.

Sequence of Events and Flight Operations

On the morning of October 16, 2025, United Airlines Flight 1093 departed Denver with 134 passengers and 6 crew members on board. The flight proceeded normally during its initial climb and established a cruise altitude of approximately 36,000 feet (FL360). At this altitude, the aircraft was traveling at a groundspeed of roughly 395 knots. The skies near Moab, Utah, appeared clear, and operations were standard until approximately 06:44 MDT.

The Collision and Immediate Aftermath

According to the preliminary report, the situation changed instantly when the captain observed an object positioned immediately ahead of the aircraft. Due to the high closure rate typical of jet travel at cruising speeds, there was little time to react. Moments later, the object struck the first officer’s forward windshield. The force of the impact was significant enough to shatter the outer pane of the multilayered window structure.

The collision resulted in glass debris entering the cockpit environment. The captain sustained minor injuries, specifically cuts and bruises to his right arm, caused by the fragmented glass. Despite the breach of the outer pane, the aircraft’s pressurization system remained stable, a testament to the fail-safe design of modern aircraft windshields. Following the impact, the first officer assumed control of the aircraft, as the crew initiated emergency protocols.

The flight crew declared an emergency and executed the necessary checklists to ensure the safety of the passengers and the aircraft. They made the decision to divert to Salt Lake City International Airport (SLC). The descent and approach were conducted without further incident, and the aircraft landed safely on runway 16L. Following the landing, the plane was able to taxi to the gate under its own power, avoiding the need for a tow and allowing passengers to deplane safely.

“The object has been identified as a lost weather balloon operated by WindBorne Systems.”

Investigation Findings: Object Identification

The primary focus of the NTSB investigation was to positively identify the object that struck Flight 1093. Initial public speculation had suggested the possibility of space debris or a natural phenomenon, given the altitude of 36,000 feet. However, forensic analysis and flight tracking data have ruled out these theories. Investigators successfully traced the object to a Global Sounding Balloon operated by WindBorne Systems.

Trajectory and Tracking Data

The investigation revealed that the balloon in question had been launched the previous day from Spokane, Washington. WindBorne Systems, the operator, reported that they had lost communication with one of their balloons in the exact vicinity and timeframe of the collision. The last data transmission received from the balloon indicated it was at an altitude of 35,936 feet as it traversed Utah airspace.

The geometry of the collision highlights the challenges of detecting small, unmanned objects at high speeds. Flight data indicates that the United Airlines Boeing 737-8 was traveling southwest. Conversely, the balloon’s last reported track suggests it was drifting in a direction nearly opposite to the aircraft’s flight path. This head-on or near-head-on trajectory created a high-speed closure rate, intensifying the force of the impact upon collision.

WindBorne Systems describes their equipment as lightweight, unmanned free balloons. These devices typically consist of a thin-film envelope, avionics for data collection, and a low-density ballast system. While they are engineered to minimize impact forces, essentially designed to be fragile, the physics of a collision at jet cruise speeds can still result in significant kinetic energy transfer, as evidenced by the damage to the aircraft.

Structural Analysis and Safety Context

A critical component of the NTSB’s preliminary report focuses on the damage sustained by the Boeing 737-8 and the engineering standards that prevented a more catastrophic outcome. The windshield of a 737-8 is a complex, multilayered structure designed specifically to maintain cabin pressure and structural integrity even in the event that an outer pane fails.

Windshield Integrity and Certification

The aircraft’s windshield is certified to withstand significant impacts, including a four-pound bird strike. In this incident, the outer pane shattered, but the inner layers held, preventing rapid decompression. The damaged windshield has since been removed from the airframe and transported to the NTSB Materials Laboratory for a detailed microscopic examination. This analysis will help engineers understand the precise mechanics of the failure and verify that the materials performed as intended under the stress of the collision.

This incident has prompted a review of safety protocols regarding high-altitude balloon operations. While the investigation is ongoing, reports indicate that United Airlines and the Federal Aviation Administration (FAA) are reviewing the event to determine if operational changes are required. There are reports that immediate adjustments were made to minimize time spent at specific altitudes in affected areas, though these operational changes will likely be refined as the final report is completed.

Conclusion

The NTSB preliminary report on United Airlines Flight 1093 provides a factual resolution to the mystery of the October 16 incident. By identifying the object as a WindBorne Systems weather balloon, the investigation shifts focus from speculation to the practical management of shared airspace. The successful diversion and safe landing underscore the resilience of modern aircraft design and the professionalism of the flight crew under pressure.

As the investigation continues, the NTSB will analyze data from the cockpit voice recorder (CVR) and flight data recorder (FDR). A final report, which will include the probable cause and official safety recommendations, is expected to take between 12 and 24 months to complete. We will continue to monitor these developments as they provide vital insights for future aviation safety standards.

FAQ

Question: What object hit United Airlines Flight 1093?
Answer: The NTSB identified the object as a lost weather balloon operated by WindBorne Systems.

Question: Were there any injuries reported?
Answer: The captain sustained minor injuries, including cuts and bruises, from glass debris. No passengers or other crew members were injured.

Question: Did the cabin lose pressure during the incident?
Answer: No. Although the outer pane of the windshield shattered, the inner layers remained intact, and cabin pressurization remained stable throughout the diversion.

Sources

• NTSB Preliminary Report DCA26LA012