DCA24FA120

The captain's decision not to establish and maintain deceleration devices in accordance with company training and standard operating procedures.

United Airlines flight 2477 departed taxiway SC while turning off of runway 27 at high speed after landing at George Bush Houston Intercontinental Airport (IAH), Houston, Texas. As flight 2477 departed the paved taxiway, the left main landing gear impacted a concrete structure recessed in the ground adjacent to taxiway SC. This impact resulted in separation of the left main landing gear. Postaccident examination of the airplane found nothing anomalous that precluded normal operation of the landing gear and the wheel braking system. Furthermore, the flight crew reported no anomalous operation of the autobrake system, the speedbrake system, or the thrust reversers during the landing rollout. The captain stated, and the flight data recorder (FDR) data confirmed, that he retracted the speedbrakes about 6 seconds after landing in order to turn off the autobrakes. Additionally, only engine idle reverse thrust was used after touchdown. By not using maximum reverse thrust upon touchdown and by turning off the autobrakes shortly after landing, the captain failed to follow multiple company standard operating procedures (SOPs) that would have assured deceleration of the airplane. The captain delayed application of maximum manual wheel braking after turning off the autobrakes, and the airplane remained at high speed as it neared the end of the runway. Speedbrake deployment increases wing aerodynamic drag and reduces wing aerodynamic lift, thereby slowing the airplane and increasing main landing gear wheel loading for more effective wheel braking. By stowing the speedbrakes shortly after landing, the wheel brakes were less effective in decelerating the airplane when the captain eventually applied maximum manual wheel braking. Had the captain used timely and effective manual wheel braking with the speedbrakes deployed, the airplane would have been capable of decelerating to a safe taxi speed before exiting the runway. The flight crew did not conduct a thorough briefing of the airplane’s landing performance when the captain changed the autobrake setting from 2 to 1, which decreased the target deceleration rate for the autobrake system. Furthermore, the flight crew did not effectively discuss potential threats, such as the wet runway condition, and appropriate threat mitigations in an arrival briefing. When the captain changed the autobrake setting to 1, the first officer (FO) accepted this deviation from the established autobrake SOP without further discussion, missing an opportunity to exhibit good crew resource management by discussing potential risks associated with this action. Lastly, a thorough arrival briefing could have identified and reminded the flight crew of a paved blast pad within the normal runway safety area (RSA) at the end of runway 27. This blast pad and RSA infrastructure provided an opportunity to decelerate to a safe taxi speed for full stop on paved and non-paved, obstacle-free surfaces instead of attempting to turn onto taxiway SC at high speed.

The captain was hired by United Airlines in April 1987 and was upgraded to captain in March 2007. His most recent training on landing performance and crew resource management was on February 26, 2024. He last completed recurrent ground school on January 2, 2024. His most recent Line Oriented Flight Training and Line Operating Evaluation were completed on August 6, 2023 and August 7, 2023, respectively. The FO was hired by United Airlines in October 2019. His most recent training on landing performance and crew resource management were on January 31, 2024. Additionally, his last Line Oriented Flight Training and Line Operating Evaluation were completed on January 31, 2024. He last completed recurrent ground school on November 19, 2023. On March 8, 2024, about 0758 central standard time (CST), United Airlines flight 2477, a Boeing 737-8, N27290, departed taxiway SC after turning off of runway 27 at high speed after landing at IAH (see figure 1). The left main landing gear departed the paved surface and impacted a concrete structure, that was recessed in the ground, resulting in its separation (see figures 2 and 3). None of the 6 crew and 160 passengers were injured and deplaned via airstairs. Flight 2477 operated as a Title 14 Code of Federal Regulations Part 121 scheduled domestic passenger flight from Memphis International Airport (MEM), Memphis, Tennessee to IAH. Figure 1. The accident airplane’s position data from ADS-B overlayed on a Google Earth image of runway 27 and taxiway SC. The green arrows show the airplane’s direction of travel. Figure 2. The accident airplane after the taxiway excursion. Figure 3. The concrete electrical manhole hit by the left main landing gear. According to the flight crew, the captain was the pilot flying and the FO was the pilot monitoring. The captain said he observed the reported runway surface condition codes when checking the automatic terminal information system (ATIS) via his electronic flight bag (EFB). Specifically, the captain recalled seeing a runway condition assessment matrix (RCAM) condition code of 3/3/3 for runways 26L and 26R and a condition code of 5/5/5 for runway 27. At the time of the accident, the RCAM code broadcast by the ATIS for runway 27 was 3/3/3, indicating the entire runway was “slippery when wet” and that braking deceleration would be noticeably reduced for the wheel braking effort applied or that directional control would be noticeably reduced. When the flight crew checked in with Houston Approach Control, they were told to expect a landing on runway 26L. The captain asked the FO to request a landing on runway 27 instead. The FO made, and the controller approved, this request, and issued instructions for the instrument landing system (ILS) approach to runway 27. The captain asked the FO to request approval to roll to the end of runway 27, which the FO stated he would do and the captain replied that, if approved, they would change the autobrakes setting from 2 to 1, which would reduce the deceleration rate for the autobrake system. About 7 miles from the runway 27 arrival threshold, the FO contacted Houston Tower and asked “how’s our spacing looking? Can we roll it all the way to the end?” to which Houston Tower responded “uh…keep your speed up. That’s approved.” The captain subsequently changed the autobrake setting from 2 to 1. The approach was conducted in instrument meteorological conditions (IMC) and, according to the flight crew, the airplane broke out of the clouds between 800 and 1,000 feet msl. They reported that visibility under the clouds was good, and the captain recalled that the runway appeared dry. The FO recalled that the runway appeared wet. The crew stated that the touchdown was uneventful, at an appropriate speed, and within the touchdown zone. The speedbrakes extended normally, and the thrust reversers were deployed to idle reverse thrust. The captain said that, shortly after touchdown, he disable the autobrakes by moving the speedbrake lever to its down and locked position, which also retracted the speedbrakes. He did not “slow too much initially” because the runway appeared dry, he wanted to expedite their time on the runway, and because he preferred decelerating gradually for passenger comfort. The captain recalled applying wheel brakes manually, about 6,000 feet from the end of the runway, but felt as if the deceleration was less than normal. He recalled hearing the runway awareness and advisory system (RAAS) alert indicating 1,000 ft of runway distance remaining. He became concerned and began applying more pressure to the brakes. As he approached the end of the runway, he elected to attempt to turn onto taxiway SC by utilizing the steering tiller and rudder pedals, while pushing aggressively on the brake pedals. The captain felt the fuselage and rudder/brake pedals begin to shake violently, as the aircraft turned onto the taxiway. He briefly released the brake pressure and the shaking ceased. He then reapplied aggressive brake pressure and the shaking resumed. The airplane departed taxiway SC and the left main landing gear tires and nose wheels tires entered the grass before the airplane came to a rest with its left wing low. Portions of the left main landing gear and its doors, as well as portions of the left wing flaps, partially separated from their normally installed locations on the airplane during the accident. The left main landing gear had rotated aft from its normal position and its tires were in contact with the inboard flap. The fuse pins for the forward trunnion bearing housing assembly of the left main landing gear had sheared. This bearing housing assembly remained attached to the outer cylinder of the left main landing gear. The aft trunnion pin of the left main landing gear had dislodged from the main landing gear beam and remained on the outer cylinder, with no damage found on the trunnion pin. The main landing gear beam aft trunnion spherical bearing remained installed in the main landing gear beam but was damaged and out of its normal position. The main landing gear beam exhibited gouging damage. Figure 4. The left main landing gear was displaced aft of its normal position. There was no visible damage to the forward and aft spars of the left wing structure. The integrity of the left wing fuel tank was not compromised. The lower-aft fuselage skin showed abrasion and deformation consistent with ground contact. The left engine nacelle exhibited abrasion damage to the fan cowl and thrust reverser consistent with ground contact. According to the Line Operations Safety Audit (LOSA) Collaborative, which developed the method in the early 2000s, a LOSA was a “peer-to-peer observational methodology based on the capture of qualitative and quantitative threat and error management (TEM) performance data of frontline personnel in their natural work conditions.” The LOSA Collaborative assisted major airlines with LOSA implementation that could take the form of either a “snapshot LOSA” or a “continuous LOSA.” A snapshot LOSA collected, validated, and analyzed observational data within a defined timeframe, typically six months, concluding with a report on the results. A continuous LOSA provided a constant stream of observational data over time that was managed by the airline. The operator stated that LOSAs were not evaluations and that the program collected de-identified data on crew compliance with the Flight Operations Manual (FOM) and the fleet-specific Flight Manual (FM) SOPs. Prior to 2023, United Airlines conducted snapshot LOSAs about every four years, with the most recent snapshot LOSAs conducted in 2016 and 2021. Each involved about 60 pilot-observers who were removed from the flight schedule for about 2.5 months to conduct observations full time. In mid-2023, United Airlines launched a continuous LOSA program in which a pool of about 50 trained pilot-observers performed about 25