Final Report: 737 overruns runway as crew ignores destabilized approach and company procedure

 - May 8, 2008, 6:58 AM

BOEING 737-300, BURBANK, CALIF., MARCH 5, 2000–At about 1811 PST Southwest Airlines Flight 1455, a Boeing 737-300 (N668SW), overran the departure end of Runway 8 after landing at Burbank-Glendale-Pasadena Airport (BUR). The airplane touched down traveling approximately 182 kt, and about 20 sec later, traveling approximately 32 kt, collided with a metal blast fence and an airport perimeter wall. The Part 121 flight was on an IFR flight plan operating in VMC at twilight.

After penetrating the fence and perimeter wall, the airplane came to rest on a four-lane city street east of the airport. Tire marks in a gradual arcing right turn originated on the runway about 1,500 ft before the fence. The airplane’s structure remained intact and the entire airframe was accounted for at the accident site. Major damage was confined to the nose section (mainly on the left side and the nosewheel well area) and fuselage station BS 515, which collapsed circumferentially. The nose gear was severed from the drag brace and driven aft into the electronics bay after rotating the assembly 90 deg. A portion of the nose cone and left wingtip were severed from the airframe. The major damage to the left and right wings was confined to the leading-edge devices.

Of the 142 people on board, two passengers were seriously injured; 41 passengers and the captain sustained minor injuries; and 94 passengers, three flight attendants and the first officer were uninjured.

According to Southwest Airlines records, the accident occurred on the flight crew’s first flight of that trip and had originated at Las Vegas McCarran International Airport (LAS). The crew indicated the preflight inspection was normal and no maintenance discrepancies were noted, but records show the flight departed the gate more than two hours behind schedule. The crew testified that the takeoff and en route portions of the flight to BUR were normal and uneventful.

At 1802:52 the flight crew was advised by the Southern California approach control that they should expect an ILS approach for Runway 8. Thirty seconds later, when the airplane was about 20 nm north of the budde outer marker at an altitude of about 8,000 ft, the Woodland sector controller told them to turn left to a heading of 190 deg and descend to and maintain 6,000 ft. The first officer acknowledged the instructions.

At 1804:02, about 19 nm north of the BUDDE outer marker at about 7,800 ft, the controller said, “Southwest 1455, maintain 230 [kt] or greater until advised please.“ The captain acknowledged the airspeed adjustment assignment. The Woodland controller indicated in a post-accident interview that he imposed the speed restriction as part of sequencing the flight between Southwest Flight 1713 and Executive Jet Flight 278.

At 1804:42 the first officer told the captain that the target airspeed for the approach would be 138 kt and that the wind was “down to six knots.“ A few seconds later he confirmed that aircraft were landing at BUR on Runway 8. At 1805:08, when the airplane was about 16 nm north of the outer marker at about 6,000 ft, the controller instructed the crew to “turn left heading 160.“ At 1805:13 the captain indicated to the first officer that ATC “wants 230 knots or greater, for a while.“

At 1805:54 the Woodland controller cleared the crew to descend to and maintain 5,000 ft and advised them they were following company traffic [Southwest Airlines Flight 1713] at their “one o’clock and 12 miles [ahead of them] turning onto the final out of 4,600.“ The FO acknowledged the clearance.

At 1807:43 the Woodland controller cleared Flight 1455 to descend to and maintain 3,000 ft. The FO acknowledged the clearance and a few seconds later he notified ATC he had the Southwest traffic in sight. At 1808:19 the controller issued an altitude restriction: “Cross Van Nuys at or above 3,000, cleared visual approach runway 8.“ The first officer acknowledged the clearance. At 1808:36, as the airplane was descending through about 3,800 ft, the captain began turning to the left for the final approach.

According to the CVR, at 1809:28, when the airplane was at an indicated airspeed of about 220 kt, the captain called for “flaps five“ and a few seconds later the captain called for “gear down.“ He later told the NTSB at that point in the flight, he noted a 20-kt tailwind indication on the flight management system screen. At 1809:53, the BUR tower controller stated, “Southwest 1455, wind, uh…210 at six [knots], Runway 8, cleared to land.“ Simultaneously, the captain called for “flaps 15.“ At 1810:01 the captain again called for “flaps…15“ and “[flaps] 25.“

From 1810:24 until 1810:59 GPWS alerts were being continuously broadcast in the cockpit, first as “sink rate“ and then, at 1810:44, switching to “whoop, whoop, pull up.“ At 1810:29, the captain stated, “Flaps 30, just put it down.“ At 1810:33 the captain stated, “Put it to [flaps] 40. [I]t won’t go, I know that. [I]t’s all right. [F]inal descent checklist.“ After the GPWS “pull up“ alert sounded at 1810:47, the captain stated, “That’s all right.“ A final “sink rate“ warning was recorded at 1810:55.

The first officer stated in a post-accident interview that instead of reading the final-descent checklist, he visually confirmed the checklist items and remembered seeing the captain arm the ground spoilers. The first officer also stated that when the captain called for flaps 40, the airspeed was about 180 kt and went as high as 190 kt during the approach. The first officer indicated that he pointed to his airspeed indicator to alert the captain of the flap-limit speed of 158 kt at flaps 40.

The captain told Safety Board investigators that he remembered hearing the “sink rate“ warning from the GPWS but that he did not react to the warning because he did not feel that he had to take action. He said that he did not remember any other GPWS warnings during the approach. The first officer indicated in a post-accident interview that he heard both the “sink rate“ and the “pull up“ GPWS warnings, though he believed the captain was correcting.

The first officer indicated to investigators that he selected the “progress“ page on the FMS cockpit display unit but that he could not recall what the wind values were during the approach. He told investigators that he was concerned that the groundspeed was faster than normal but added that he did not verbalize his concern to the captain. The first officer said he believed the approach was stabilized and that they were in a position to land.

The captain told the NTSB he was aware that Southwest Airlines’ standard procedure was for the captain and first officer to call “1,000 [feet agl], airspeed and sink rate“ when descending through 1,000 ft. However, no such callouts were recorded by the CVR. He also stated he visually perceived that the airplane was “fast“ as it crossed the approach end of Runway 8. CVR and FDR data indicate that the airplane touched down at 1810:58 with flaps extended to 30 at about 182 kt; flaps then extended to 40 during the ground roll at about 145 kt.

The captain told the NTSB that after touchdown the end of the runway appeared to be closer than it should have been and that he thought they might hit the blast-fence wall. The captain indicated that he braked “pretty good“ while attempting to stop the airplane. FDR data indicate that the captain unlocked the thrust reversers 3.86 sec after touchdown and that the thrust reversers deployed 4.91 sec after touchdown.

When investigators asked the captain in a post-accident interview whether he was within company operating guidelines at 1,000 and 500 ft, the captain responded, “No.“ He said that the airport looked normal at 500 ft but that he was not “in the slot“ because his airspeed was too high. When Board investigators questioned the captain about whether Southwest Airlines had guidance concerning the abandonment of an approach, the captain stated that if the airplane was not set up at 1,000 ft, with flaps at five degrees, gear extended and on glideslope, a go-around maneuver should be performed. He indicated that he became “fixated on the runway,“ and he could not explain why he did not perform a go-around maneuver.

The first officer told investigators that the captain applied the wheel brakes before the airplane had decelerated to 80 kt and that as the airplane passed the Southwest Airlines passenger boarding gates he joined the captain in applying the brakes as hard as he could. The captain indicated that as the airplane neared the end of the runway he initiated a right turn using only the nosewheel steering tiller (not the rudder pedals). At 1811:20, the cockpit microphone recorded impact sounds.

The airplane departed the right side of the runway about 30 deg from the runway heading, penetrated a metal blast fence and an airport perimeter wall, and came to a stop on a city street off the airport property. An emergency evacuation ensued, and all crewmembers and passengers exited the airplane.

The 52-year-old captain held an ATP license issued in 1979, with the ratings and limitations of airplane multi-engine land; commercial privileges for airplane single-engine land; and type ratings for the 737, Gulfstream G-159 and Convair CV-240, -340 and -440. At the time of the accident, he had approximately 11,000 hr TT. He had flown 737s for Southwest Airlines for a total of 9,870 hr, 5,302 of which were as pilot-in-command. His first-class medical was current.

At the time of the accident, the 43-year-old first officer held an ATP certificate issued in 1995 with the ratings and limitations of airplane multi-engine land; commercial privileges for airplane single-engine land; and 737 type rating. He had been hired by Southwest Airlines in 1996 and had about 5,022 hr TT at the time of the accident. He had 2,522 hr in 737s at Southwest. His first-class medical certificate was current. Neither pilot tested positive for drugs or alcohol.

Weather conditions reported about the time of the accident were wind from 250 deg at six knots, visibility 10 statute miles, ceiling overcast at 9,500 ft, temperature 9 deg C, dew point 0 deg C and altimeter 29.66 in. BUR reported that 0.77 in. of rain had fallen in the eight hours before the accident and that a wind shift associated with a cold frontal passage had occurred. Runway 8 was wet at the time of the accident.

Runway 8, at 6,032 ft long and 150 ft wide, is configured for precision instrument landings and equipped with high-intensity runway-edge lights, distance-to-go markers and a medium-intensity approach lighting system with runway alignment indicator lights. A precision approach path indicator (PAPI) is located 1,520 ft from the approach end of Runway 8 on the left side.

The NTSB determined that the probable cause was the flight crew’s excessive airspeed and flight-path angle during the approach and landing and its failure to abort the approach when stabilized approach criteria were not met. Contributing to the accident was the controller’s positioning of the airplane in such a manner as to leave no safe options for the flight crew other than a go-around maneuver.