N752SW

HISTORY OF FLIGHTOn December 6, 2018, about 0903 Pacific standard time, Southwest Airlines (SWA) flight 278, a Boeing 737-7H4, N752SW, overran the end of runway 8 during the landing roll at Bob Hope Airport (BUR), Burbank, California, and came to rest in the engineered materials arresting system (EMAS) at the departure end of the runway. The 2 pilots, 3 flight attendants, and 112 passengers were not injured. The airplane sustained minor damage. The regularly scheduled domestic passenger flight was operating under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121. Instrument flight conditions prevailed at the time of the incident, and an instrument flight rules flight plan was filed.

The flight departed from Metropolitan Oakland International Airport, Oakland, California, about 0810. The captain was the pilot flying, and the first officer was the pilot monitoring.

About 0822, the flight crew requested, via the aircraft communications addressing and reporting system (ACARS), the weather at BUR and received automatic terminal information service (ATIS) information Hotel, which was issued at 0753. The ATIS information indicated that the wind was from 280° at 5 knots, visibility was 1 1/4 miles in heavy rain and mist, and the ceiling was broken clouds at 1,100 ft above ground level (agl).

About 0824, the crew received, via ACARS, a landing data report generated from the company’s performance weight and balance (PWB) system. The report was based on the reported wind from the most recent meteorological aerodrome report (290° at 5 knots) converted to bearing from magnetic north (278° at 5 knots), the airplane’s estimated landing weight (120,800 pounds), the planned flap setting (40°), and the reported runway condition (good). (Note: The wind direction in meteorological aerodrome reports and similar products is relative to true north, and the wind direction provided by air traffic control [ATC] and in ATIS reports is relative to magnetic north. At BUR, magnetic north is 12° east of true north.) The report indicated that maximum autobrakes should be used for landing on runway 8 (which was 5,802 ft in length) and that the stopping margin (that is, the distance between the location where the airplane should come to a stop, plus a 15% safety factor, and the end of the runway) would be 245 ft. The stopping margin calculation assumed, among other things, a touchdown at 1,500 ft from the runway threshold. According to the cockpit voice recorder (CVR), the flight crewmembers were concerned about the stopping distance given the wet runway, the tailwind conditions, and the runway length. Also, the captain and first officer discussed that, because of the runway conditions, the braking would be “pretty abrupt.”

At 0848:14, the CVR recorded a controller from the Los Angeles Air Route Traffic Control Center informing the flight crew about “moderate to heavy to extreme” precipitation between the airplane’s position at the time and BUR. The center controller transferred the flight to the next ATC facility, the Southern California Terminal Radar Approach Control; at 0851:27, the approach controller instructed the flight crew to descend the airplane to 8,000 ft and expect the “ILS [instrument landing system] Zulu” runway 8 approach to BUR. The first officer acknowledged the instructions and advised the controller that they had ATIS information Hotel. Upon reaching MIKEI, an initial approach fix for the approach, the controller cleared the flight crew to conduct the approach. Between 0854:37 and 0854:51, the controller advised the flight crew that, about 10 minutes earlier, the pilot of King Air airplane reported a 15-knot loss of airspeed on final approach to BUR and that a corporate jet had just conducted a goaround at BUR. About 2 minutes later, the controller informed the flight crew that the goaround occurred because of the wind. The first officer acknowledged this information.

According to the company’s PWB system, the reference landing speed was 126 knots (indicated airspeed), and the target speed was 131 knots. Flight data recorder (FDR) data showed that, about 0858, the airplane turned onto its final heading and captured the glideslope and localizer for the ILS approach. About 1 minute later, the flight crew selected a flap setting of 40°, and the airplane’s indicated airspeed was between 133 and 136 knots.

At 0858:54, the approach controller instructed the flight crew to contact the BUR ATC tower, and the first officer acknowledged this instruction and made initial contact with the tower at 0859:17. Between 0859:21 and 0859:36, the tower controller advised the flight crew about “moderate to heavy precipitation” between the flight’s position at the time and the airport, stated that the wind was 260° at 9 knots, and cleared the airplane to land on runway 8. The controller also advised the flight crew that, 10 minutes earlier, the pilot of a Boeing 737 airplane reported braking action as “good.” Less than 1 minute later, the controller further advised that heavy precipitation was directly over the airport. The first officer acknowledged each of the transmissions from the controller.

At 0900:43, the controller stated that the wind was from 270° at 10 knots. Five seconds later, the first officer stated to the captain that 10 knots “is the max,” referring to the 10-knot tailwind limitation for landing in the SWA B737NG Aircraft Operating Manual (AOM); the captain also stated “max” and noted that the autopilot “has got a handle on it” thus far. At 0901:33, the captain asked that the windshield wipers be set to high. Three seconds later, the controller stated that the wind was from 270° at 11 knots. At 0901:52, the first officer stated, “we got eleven knots. You want to call it good?” The captain replied, “yeah.” During postincident interviews, the captain stated that he and the first officer agreed that the tailwind component would be about 9 to 10 knots and thus within the limit, and the first officer described the 11-knot wind as being “right on the edge” of the tailwind limit.

During a postincident interview, the captain reported that, when the airplane was about 400 ft agl, the airplane exited the clouds, and he had a clear view of the runway. The captain also reported that, at the decision altitude of 1,007 ft mean sea level (about 280 ft agl), he disconnected the autothrottles and the autopilot and continued to descend using the precision approach path indicator lights as a descent path reference. (The CVR recorded the captain stating, “we need some kind of lights. I got some lights,” about that time.) The captain further reported that, during the landing flare (when the airplane was about 5 ft agl), the rain intensity “picked up and visibility decreased a little bit.”

The National Transportation Safety Board’s aircraft performance study for this incident found that the airplane crossed the runway threshold at an altitude of 54 ft agl and an indicated airspeed of 137 knots. (The ILS runway 8 approach procedure noted a threshold crossing height of 60 ft when following the 3° glideslope.) The captain reported (during a postincident interview) that he was aware of the 1,000ft markers as the airplane crossed the runway threshold. FDR data showed that the airplane touched down at 0902:35 at an indicated airspeed of 126 knots and a groundspeed of 151 knots.

During postincident interviews, the captain estimated that the airplane touched down between 1,300 and 1,500 ft from the runway threshold based on the timing from about 10 ft agl to touchdown (and not runway markings). The first officer stated that the airplane touched down within the touchdown zone, which he defined as 1,000 to 1,500 ft from the threshold, and was “pretty confident” that the airplane touched down by 1,500 ft. The aircraft performance study found that the airplane touched down 2,504 ft from the runway threshold. A controller in the BUR tower observed the airplane touch down near the taxiway D7 intersection with runway 8, which was about 2,600 ft from the runway threshold. This observation was consistent with the related finding from the aircraft performance study.

According to the FDR, the airplane’s autobrakes, auto speedbrakes, and ground spoilers were activated at touchdown. Both thrust reversers were fully deployed within 3 seconds of touchdown. Brake pressure reached its maximum of 3,000 psi in about 6 seconds. At 0902:45, the CVR recorded the first officer stating, “come on baby,” which was followed by the captain stating “whoa-ah” and then expletives. The CVR recorded sounds of impact at 0902:56.

The captain stated that, after touchdown, he used maximum reverse thrust and that he heard and felt the brakes “chattering.” He verified that the speedbrake handle was extended and started “blending in manual brakes after that” because the airplane was not slowing with reverse thrust and maximum autobrakes. The captain became concerned about the airplane stopping as it passed runway 15/33 (which intersected with runway 8 about 3,765 ft from the runway 8 threshold). The captain noted that, with 1,000 to 500 ft remaining on the runway, the airplane stopped decelerating. The captain thought that he might be able to make a turn onto taxiway D1 (which intersected runway 8 about 5,340 ft from the runway threshold), but, as he tried to turn using left rudder and the tiller, the airplane did not respond. The captain reported that the nosewheel was skidding and that he straightened it so that the airplane would enter the EMAS without the nosewheel turned sideways.

FDR data showed that, during the first 17 seconds after touchdown (between 0902:35 and 0902:52), the airplane reached and maintained a deceleration rate between about 0.3 and 0.4 G, and the airplane’s groundspeed decreased from 151 to 50 knots. During the next 5 seconds, the deceleration rate decreased to between 0.15 and 0.20 G as the airplane crossed over the le...