Boeing 737 accident near Jacksonville, Florida, May 4, 2019

The NTSB's narrative final · quoted from the NTSB record

According to both pilots, the takeoff, climb, and cruise portions of the flight were uneventful. The No. 1 (left) thrust reverser was not operational and deferred for the flight in accordance with the airplane’s minimum equipment list. The captain was the pilot flying for the accident flight, and the first officer was the pilot monitoring. The captain was also performing check airman duties for the first officer who was in the process of completing operating experience training. During the approach to Jacksonville Naval Air Station (NIP), the flight crew had two runway change discussions with air traffic controllers due to reported weather conditions (moderate to heavy precipitation) near the field; the pilots ultimately executed the area navigation GPS approach to runway 10, which was ungrooved and had a displaced threshold 997 ft from the threshold, leaving an available landing distance of 8,006 ft. As the airplane descended through 1,390 ft mean sea level (msl), the pilots configured it for landing with the flaps set at 30º and the landing gear extended; however, the speedbrake handle was not placed in the armed position as specified in the Landing checklist. At an altitude of about 1,100 ft msl and 2.8 nm from the runway, the airplane was slightly above the glidepath, and its airspeed was on target. Over the next minute, the indicated airspeed increased to 170 knots (17 knots above the target approach speed), and groundspeed reached 180 knots, including an estimated 7-knot tailwind. At an altitude of about 680 ft msl and 1.6 nm from the threshold, the airplane deviated further above the 3° glidepath such that the precision approach path indicator (PAPI) lights would have appeared to the flight crew as four white lights and would retain that appearance throughout the rest of the approach. Eight seconds before touchdown, multiple enhanced ground proximity warning system alerts announced “sink rate” as the airplane’s descent rate peaked at 1,580 fpm. The airplane crossed the displaced threshold 120 ft above the runway (the PAPI glidepath crosses the displaced threshold about 54 ft above the runway) and 17 knots above the target approach speed, with a groundspeed of 180 knots and a rate of descent about 1,450 ft per minute (fpm). The airplane touched down about 1,580 ft beyond the displaced threshold, which was 80 ft beyond the designated touchdown zone as specified in the operator’s standard operating procedures (SOP). After touchdown, the captain deployed the No. 2 engine thrust reverser and began braking; he later reported, however, that he did not feel the aircraft decelerate and increased the brake pressure. The speedbrakes deployed about 4 seconds after touchdown, most likely triggered by the movement of the right throttle into the idle reverse thrust detent after main gear tire spin-up. The automatic deployment of the speedbrakes was likely delayed by about 3 seconds compared to the automatic deployment that could have been obtained by arming the speedbrakes before landing. The airplane crossed the end of the runway about 55 ft right of the centerline and impacted a seawall 90 ft to the right of the centerline, 9,170 ft beyond the displaced threshold, and 1,164 ft beyond the departure end of runway 10. After the airplane came to rest in St. Johns River, the flight crew began an emergency evacuation. The tailwind, the airplane’s excessive approach speed, and delayed speedbrake deployment increased the energy with which the airplane departed the runway and impacted the seawall, which contributed to the severity of the accident. However, postaccident landing performance calculations revealed that even if the airplane had landed on target speed within the operator’s specified touchdown zone, it would not have been able to stop before reaching the end of the paved runway surface due to the presence of standing water (with depths close to that defined as a flooded condition) on portions of the runway and the resulting viscous hydroplaning. Viscous hydroplaning is associated with the buildup of water pressure under the tire due to viscosity in a thin film of water between a portion of the tire footprint and the runway surface. The maximum wheel braking friction coefficient developed by the airplane during the landing ground roll was significantly less than the maximum wheel braking friction coefficient underlying the wet runway landing distances published in the airplane manufacturer’s flight crew operating manual (FCOM), computed by the operator’s onboard performance tool (OPT) application, and described in standards and models concerning landing performance in wet runway conditions. Conversely, had the airplane achieved the good braking action associated with a wet (but not flooded) runway published in the FCOM, it would have stopped on the runway even with the approach speed recorded before the accident landing, a 10-knot tailwind, and delayed speedbrake deployment. The operator’s guidance did not require flight crews to conduct en route landing performance calculations (landing distance assessment) under certain conditions, including reported braking action that is good or better, the use of maximum manual braking, and a tailwind of 5 knots or less. However, none of these criteria applied to the accident flight’s approach to NIP. No braking action reports were provided to or requested by the accident flight crew, the flight crew briefed using autobrakes rather than maximum manual braking, and the last wind report provided to the flight crew (240° heading at 10 knots) suggested that an estimated 7-knot tailwind component existed during the landing on runway 10. These considerations should have prompted the flight crew to perform updated landing performance calculations. However, had they done so, they still would have likely determined that the landing distance available on runway 10 was sufficient, under the conditions at the time, if they assumed good braking action (in the absence of reports indicating otherwise) and a merely wet (rather than flooded) runway condition. To address braking friction shortfalls observed during landings on wet runways, Safety Alert for Operators (SAFO) 15009 (current at the time of the accident) suggested that operators take appropriate action to address landing performance on wet runways such as “assuming a braking action of medium or fair when computing time-of-arrival landing performance or increasing the factor applied to the wet runway time-of-arrival landing performance data.” However, similar guidance was not included in the operator’s SOPs at the time of the accident. Had such guidance been included, the flight crew would have been obligated to assign a surface condition value indicating a condition worse than “good” because the runway was wet, which would have prohibited them from attempting the landing with the tailwind. To further clarify that advisory data for wet runway landings may not provide a safe stopping margin, especially in conditions of moderate or heavy rain on smooth runways, the Federal Aviation Administration issued SAFO 19003, which replaced SAFO 15009, 2 months after the accident. The new SAFO recommends that pilots verify, before initiating an approach, that the aircraft can stop within the landing distance available using a runway condition of medium-to-poor whenever there is the likelihood of moderate or greater rain on a smooth runway or heavy rain on a grooved/porous friction course runway. The operator’s SOPs would have prohibited landing if runway 10’s surface condition were assigned a value less than “good,” given the existing tailwind at the time of the accident; according to the operator’s SOPs, a “wet” runway is considered to have good braking action. Consequently, the flight crew’s ability to determine whether they could safely land on the runway was critically dependent on their ability to determine that the actual condition of the runway was worse than “good.” Notably, although not directly causal to the accident (because the worse-than-expected runway friction prevented the airplane from stopping on the runway), the airplane’s approach to NIP did not meet the operator’s stabilized approach criteria by the time the airplane descended to 1,000 ft agl, and several cues should have led the flight crew to call for a missed approach as required by SOPs. The airplane’s airspeed exceeded the target approach speed, it was above the glidepath, and its descent rate was greater than 1,000 fpm, which prompted multiple sink rate alerts that should have induced the flight crew to call for a missed approach. Additionally, the Miami Air Flight Operations Manual (FOM) required a flight crew to initiate a missed approach if the aircraft was not stabilized by 1,000 ft. At the time of the accident, the first officer had only 18 hours in the Boeing 737 and most of his previous experience was operating light aircraft. Thus, his lack of experience flying jet aircraft likely played a role in his inadequate monitoring of the approach (his lack of experience was also exemplified by his failure to note, as part of his monitoring duties, that the speedbrake handle had not been armed after calling the item as part of the Landing checklist). The captain’s continuation of the approach, contrary to the operator’s stabilized approach criteria, was likely due to a combination of factors. The first was plan continuation bias (an unconscious cognitive bias to continue with the original plan despite changing conditions). The captain’s bias may have been reinforced by a self-induced pressure to land because the flight was late due to an earlier maintenance delay and, the captain and the first officer were approaching the end of their legal duty day. A go-around or diversion to an alternate airport would have caused additional delays. Another factor was the captain’s increased workload during the approach. Flying and monitoring duties are typically divided to reduce workload for each crewmember. However, cockpit voice recorder data indicate that, rather than relay queries or responses to ATC through the first officer, the captain made multiple radio communications to the approach controller regarding the weather, despite the first officer being responsible for performing this task as part of his monitoring duties. In addition to performing some of the first officer’s radio duties, the captain was also performing check airman duties in a bad weather situation. Further, the captain’s failure to check that the speedbrake handle was armed, as part of the Landing checklist, was an oversight that was likely another result of his increased workload. Combined with plan continuation bias, the captain’s increased workload from performing additional tasks narrowed his attention and limited his ability to recognize and correctly respond to the cues of an unstabilized approach.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.