NTSB Attributes Flight 1632 Runway Excursion to Maintenance Errors

Anatomy of a Runway Excursion: The NTSB’s Final Word on Flight 1632

On February 10, 2024, American Airlines Flight 1632, a Boeing 737-823, completed its journey from Washington, D.C., to Dallas-Fort Worth International Airport (DFW). The landing, however, was anything but routine. After touching down, the aircraft was unable to stop on the runway, ultimately coming to a rest in the paved overrun area. While the 104 passengers and crew deplaned safely with no injuries reported, the incident triggered a thorough investigation by the National Transportation Safety Board (NTSB).

When an aircraft experiences a runway excursion, initial speculation often turns to pilot action, weather conditions, or a fundamental design flaw. However, the NTSB’s final report, released on November 10, 2025, steers the narrative in a different direction. The findings bypass the cockpit and the weather, focusing instead on the meticulous, high-stakes world of aircraft maintenance. The report provides a critical look at how a procedural oversight on the ground can have significant consequences in the air, offering valuable lessons for the entire aviation industry.

This breakdown will dissect the NTSB’s official findings. We will explore the sequence of events during the landing, delve into the specific maintenance errors that led to the brake failure, and examine the subsequent safety recommendations issued to prevent a similar event from happening again. The story of Flight 1632 is a stark reminder that aviation Safety is a chain of countless links, and every single one matters.

The Incident Unpacked: A Routine Landing Turns Critical

Flight 1632’s approach to DFW was, by all accounts, normal. The crew prepared for landing on runway 17L under standard conditions. The aircraft touched down as expected, but the first sign of trouble appeared almost immediately. An “AUTOBRAKE DISARM” light illuminated in the cockpit, signaling a malfunction in the automated braking system designed to slow the aircraft smoothly and efficiently after landing.

A Sudden Failure

The flight crew’s training and experience kicked in instantly. The cockpit voice recorder captured the tense moments as the situation unfolded. The first officer was recorded stating, “The brakes will not… you got it?” The captain’s response was immediate and clear: “I got it. Brakes aren’t working.” This exchange highlights the crew’s swift recognition of a complete loss of braking effectiveness. The pilots were now manually trying to control an aircraft that was not responding as it should.

With conventional braking gone, the captain took manual control and deployed maximum reverse thrust, a procedure used to rapidly decelerate the aircraft by redirecting the engines’ power forward. Despite these efforts, the Boeing 737’s momentum carried it beyond the end of the runway. The aircraft finally came to a stop in the paved overrun area approximately 30 seconds after the crew first realized the brakes had failed. Thanks to the crew’s handling of the emergency and the presence of a safety overrun area, a potentially dangerous situation was contained without injury.

The passengers and crew deplaned onto the tarmac using airstairs, and while the event was undoubtedly alarming, the immediate outcome was safe. The focus then shifted from emergency response to Investigation. The NTSB was tasked with answering a critical question: Why did a modern aircraft’s braking system, one of its most critical safety features, fail so completely upon landing?

NTSB Findings: Tracing the Failure to a Maintenance Error

The NTSB’s investigation moved away from the flight deck and into the maintenance hangar. Their final report concluded that the probable cause of the runway excursion was not a design flaw or pilot error, but improper maintenance due to human error during a braking system modification.

The Root of the Problem

Investigators discovered that just four days before the incident, the aircraft had undergone scheduled maintenance at an American Airlines facility in Tulsa. The work involved a significant modification: replacing the aircraft’s steel brakes with newer carbon brakes. This complex task was performed by a team of six mechanics, each with over three decades of experience. Yet, despite this wealth of expertise, critical connection errors were made.

The NTSB found two specific and crucial mistakes. First, the flexible hydraulic hoses for the right main landing gear brakes were swapped, meaning the lines that deliver hydraulic pressure to the brakes were improperly reconnected. Second, the wiring harnesses for the left main landing gear’s wheel speed transducers were cross-connected. These transducers are essential sensors that tell the aircraft’s systems how fast each wheel is spinning.

These seemingly small errors had a cascading effect on the aircraft’s sophisticated braking systems. The misconnections directly impacted the antiskid system, which functions much like an anti-lock braking system (ABS) in a car. Its job is to prevent the wheels from locking up during heavy braking by modulating brake pressure, ensuring maximum braking efficiency without skidding.

The NTSB report cited a key contributing factor as “the lack of a functional check to verify the flexible hydraulic hoses and transducer wiring were connected correctly after the braking system modification.”

How the Errors Caused the Failure

With the hydraulic lines and sensor wiring crossed, the antiskid system received incorrect information and sent commands to the wrong places. Instead of releasing pressure on wheels that were about to lock up, the system was unable to perform its function correctly. This led to tire failure and a severe, sudden reduction in the aircraft’s ability to slow down, precisely what the flight crew experienced upon touchdown.

Crucially, the NTSB pointed out that the maintenance procedure lacked a final, critical step: a functional check to confirm that all connections were correct before returning the aircraft to service. This oversight allowed the hidden errors to go undetected until the system was needed most, during landing. The incident became a powerful case study in the importance of not just performing maintenance correctly, but also verifying that the work was done right.

The findings underscore that in a system as complex as modern aviation, safety relies on robust processes that include checks and balances. Even the most experienced technicians can make mistakes, which is why verification protocols are not just a formality, but a fundamental layer of safety.

Moving Forward: Industry Responses and Safety Enhancements

In the wake of the NTSB’s findings, the focus has shifted to implementing measures that will prevent a recurrence. The investigation into Flight 1632 provided a clear, actionable lesson for the aviation maintenance industry. In response, The Boeing Company has issued a list of best practices aimed directly at addressing the procedural gaps identified in the report.

These recommendations are not about redesigning the aircraft but about strengthening the human processes involved in maintaining it. The new guidelines are designed to be straightforward and effective, adding layers of protection against simple human error. They serve as an industry-wide update to maintenance protocols, ensuring that the lessons from this incident are applied broadly.

The core of the recommendations involves simple yet effective verification steps. Boeing now advises maintenance teams to temporarily label flexible hydraulic hoses to ensure they are reconnected to the correct brake positions. Similarly, wiring harnesses for wheel speed transducers should be labeled when disconnected. Most importantly, the new best practices call for the implementation of functional checks to verify that all hydraulic and electrical connections are correct after any braking system modification is performed. This final step provides a critical opportunity to catch any errors before an aircraft is cleared for flight.

Conclusion: A Stark Reminder of Procedural Importance

The runway excursion of American Airlines Flight 1632 at DFW was a serious event that, fortunately, concluded without injury. The NTSB’s investigation provides a clear and sobering conclusion: this was not a failure of design or a misjudgment in the cockpit, but a consequence of a procedural lapse on the maintenance floor. It serves as a powerful case study on the absolute necessity of meticulous, verified procedures in every aspect of aviation.

The incident highlights that safety is not just about advanced technology or skilled pilots; it is equally dependent on the disciplined, process-driven work of maintenance technicians. The subsequent recommendations from Boeing aim to reinforce this discipline by closing the procedural gap that allowed this error to occur. The story of Flight 1632 is ultimately one of continuous improvement, demonstrating how the aviation industry learns from every incident to build an even safer system for the future.

FAQ

Question: What was the official cause of the American Airlines Flight 1632 runway excursion?
Answer: The NTSB determined the probable cause was improper maintenance. During a brake system modification, hydraulic hoses and wheel speed transducer wires were incorrectly connected. This led to a malfunction of the antiskid system and a subsequent loss of braking effectiveness upon landing.

Question: Were any passengers or crew injured in the incident?
Answer: No. All 104 occupants on board deplaned safely via airstairs, and no injuries were reported.

Question: What changes have been made in the industry following this event?
Answer: In response to the findings, The Boeing Company issued a list of best practices for maintenance crews. These include better labeling of hoses and wires during maintenance and, most importantly, implementing mandatory functional checks to verify all connections are correct after any work on the braking system.

NTSB Final Report