History of Flight
On February 10, 2024, about 19:42 central standard time, American Airlines flight 1632, a Boeing 737-823 (registration N991AN), experienced a brake system anomaly after landing on runway 17L at Dallas-Fort Worth International Airport (DFW), Texas. The airplane came to a stop in the paved overrun area beyond the south end of the runway threshold. All 104 passengers and crew members safely evacuated via airstairs; no injuries were reported. The flight was a scheduled domestic passenger service under 14 CFR Part 121, originating from Ronald Reagan Washington National Airport (DCA) to DFW.
The incident occurred on the final day of a four-day trip during a single-leg return flight. The first officer was the pilot flying, and the captain was the pilot monitoring. Flight data recorder (FDR) data showed no anomalies during the enroute phase. Cockpit voice recorder (CVR) data indicated that the crew briefed a visual approach to runway 17L with flaps 30. The captain stated autobrakes were set to level 3 due to a reported tailwind of one knot. Both the approach and touchdown were reported as normal.
At 19:41:33, a touchdown sound was captured. FDR data showed main landing gear transition to ground, airspeed 141 knots, ground speed 150 knots, and all ground spoilers deployed. About one second after touchdown, the autobrake parameter changed from 'No Auto Brake' to 'Auto Brake applied' then immediately reverted to 'No Auto Brake', indicating autobrake deactivation. The crew reported seeing the AUTOBRAKE DISARM light illuminate and applied manual braking. At 19:41:38, the first officer said 'and, manual brakes' followed by the captain stating 'autobrakes are off'.
Approximately seven seconds after touchdown, right brake pressure peaked at about 3,000 psi; left brake pressure peaked similarly about six seconds later. Thrust reversers deployed, remained for 12 seconds, stowed for six seconds, then redeployed. The crew reported slower deceleration than expected. At 19:41:52, the captain called '80 knots' and took control, stating 'brakes aren't working.' At 19:42:07, the first officer informed DFW tower of no braking capability; tower instructed an arriving airplane to go around.
FDR data recorded abrupt acceleration changes at 19:42:28, consistent with an overrun beyond the runway threshold. The airplane stopped five seconds later. Maximum longitudinal deceleration during rollout was -0.27 g.
Aircraft Information
The incident airplane was a Boeing 737-800 series with retractable tricycle landing gear. The normal braking system uses hydraulic system B, controlled by brake pedals via cables to metering valves. The antiskid/autobrake control unit (AACU) monitors and controls braking. The autobrake system disarms when manual brake pressure meets or exceeds 750 psi, triggering the AUTOBRAKE DISARM light. FDR data showed that the autobrake engaged briefly after touchdown, then disengaged because left normal brake metering valve pressure exceeded 750 psi, after which the crew manually controlled braking.
Examination Findings
Post-incident inspection of tires revealed that the left and right main landing gear outboard tires (numbers 1 and 4) had significant damage, including flat spots worn through all plies and 'X' pattern ruptures consistent with high-energy lateral loading from a skid event. The inboard tires and nose landing gear tires showed normal wear with no damage.
Troubleshooting by American Airlines identified that flexible hydraulic hoses to the right main landing gear brakes had been improperly reconnected during previous maintenance, with hoses for the number 3 and number 4 brakes swapped. This caused the antiskid system to release brake pressure to the wrong wheel, leading to continued skidding on the skidding wheel and reduced braking on the non-skidding wheel. Additionally, the wiring harness for the left main landing gear wheel speed transducers was incorrectly installed, with connectors for the number 1 and number 2 transducers swapped, causing a similar effect on the left side.