This article is based on official investigative data and documents released by the National Transportation Safety Board (NTSB) regarding the March 2024 United Airlines Flight 2477 incident.

NTSB Docket Reveals Critical Disconnect in United Airlines 737 MAX Runway Excursion

The National Transportation Safety Board (NTSB) has opened the public docket for its ongoing investigation into the March 8, 2024, runway excursion involving United Airlines Flight 2477. The Boeing 737-8 MAX, registered as N27290, veered off the runway after landing at George Bush Intercontinental Airport (IAH) in Houston, Texas, resulting in the collapse of its left main landing gear.

Newly released documents highlight a significant discrepancy between the flight crew’s perception of the landing environment and the actual runway conditions. According to the investigative reports, the Captain believed the runway was dry and braking action was “Good,” while data indicates the surface was wet and slippery. This misperception appears to have influenced critical operational decisions, including the selection of a low autobrake setting.

While the investigation is ongoing and a final probable cause has not yet been determined, the factual reports provide a detailed look into the human factors and external pressures present in the cockpit during the incident.

Conflicting Assessments of Runway Conditions

The central finding in the newly released documents is the conflict regarding runway condition codes, which are essential for determining landing performance and braking requirements. The NTSB docket reveals that the Captain, who was the Pilot Flying, recalled seeing condition codes of 5/5/5 for Runway 27 on the Automatic Terminal Information Service (ATIS).

In aviation standards, a code of 5 corresponds to “Good” braking action, typically associated with a wet surface that is not slippery. However, investigators found that the actual ATIS broadcast at the time of the incident reported codes of 3/3/3. A code of 3 indicates “Medium” braking action, warning pilots that the runway is slippery when wet.

This disconnect extended to visual perception. The First Officer, serving as the Pilot Monitoring, correctly identified the runway as “wet.” In contrast, the Captain maintained the assessment that the runway appeared “dry,” a belief that directly impacted the braking strategy employed during the landing roll.

Braking Decisions and High-Speed Exit

Based on the perception of favorable conditions, the flight crew made decisions that reduced the aircraft’s deceleration rate. NTSB data indicates that the Captain selected “Autobrake 1,” the lowest available setting. United Airlines standard operating procedures generally recommend higher autobrake settings (such as MAX) when runway conditions are slippery or uncertain.

The docket further reveals that manual braking was not applied until the aircraft was approximately 6,000 feet down the runway. The crew attempted to exit the runway onto Taxiway SC, a high-speed exit, while traveling at approximately 39 knots. Investigators noted that this speed was excessive for the wet surface conditions present at the time.

As the aircraft attempted the right turn, the tires lost traction. The 737 MAX skidded off the paved surface into the grass, where the left main landing gear struck a concrete electrical junction box. The impact caused the gear to separate, and the aircraft came to rest on its left wing and engine nacelle. Fortunately, no injuries were reported among the 160 passengers and 6 crew members.

External Pressures and ATC Instructions

The investigation also sheds light on external factors that may have contributed to the crew’s decision-making. Transcripts included in the docket show that Houston Tower instructed the crew to “keep your speed up” during the approach to accommodate a tight arrival sequence.

Investigators suggested that this instruction might have created a “sense of urgency” in the cockpit to clear the runway quickly. The Captain reportedly requested to roll to the end of the runway to shorten the taxi time to the gate, a maneuver he stated he had performed “hundreds of times” in his career. The Captain is a veteran pilot with over 15,000 flight hours, including more than 9,600 hours on the Boeing 737, and had completed landing performance training just one month prior to the accident.

AirPro News Analysis

The release of these factual reports underscores a recurring theme in runway excursions: the danger of confirmation bias. When a pilot expects a “dry” runway based on prior experience or a misread report, they may subconsciously filter out contradictory visual cues, such as the “wet” appearance noted by the First Officer.

Furthermore, the “keep your speed up” instruction from Air Traffic Control highlights the subtle but powerful pressure placed on crews at high-volume hubs like Houston. While safety is always the priority, the operational drive to maximize runway throughput can inadvertently encourage crews to push the boundaries of stable deceleration, particularly when environmental conditions are worse than anticipated.

Next Steps in the Investigation

The opening of the public docket marks a significant phase in the NTSB’s process, allowing industry experts and the public to review the factual basis of the investigation. The docket includes operational factors reports, human performance studies, and transcripts from the Cockpit Voice Recorder (CVR).

The NTSB has not yet issued a final report. The board will continue to analyze the gathered data to determine the official probable cause of the accident and may issue safety recommendations to prevent similar occurrences in the future.

Sources:

• NTSB Public Docket (Project ID 193898)