AOPA Pilot Magazine - April 2012 - 76

SAFETYPILOT
About 10 minutes earlier, the tower had decided to change runways because of shifting winds from the nearby storms. The pertinent parts of the ATIS noted a temperature of 88 degrees Fahrenheit, winds 300 degrees at 17 knots, and lowlevel wind-shear advisories. However, the flight’s dispatch package had been based on using Runway 21L or 21R, and Runway 3 Center was the shortest of the three parallels at 8,500 feet. The captain asked the FO to verify that they could use that runway because of the high ambient temperature and the full load. The captain then missed the turn onto taxiway Charlie and had to be redirected. Ground control, again, provided the new ground frequency to the captain while the FO was looking up the departure requirements. At 8:42:11, the flight taxied into position on Runway 3C and waited. ATC advised to expect a three-minute delay to establish “in-trail separation behind traffic just departing” and at 8:44:04 takeoff clearance was issued. That would have been a great time to make one last check of the critical items. The cockpit voice recorder (CVR) showed engine power increasing at 8:44:21 p.m. At 8:44:45 the FO called 100 knots and “Rotate,” 12 seconds later at 8:44:57. Eight seconds after that, the stall-warning stick shaker activated. It continued until impact, with continuous aural tones and voice warnings. However, at no time during the takeoff did the takeoff warning system activate that would

have indicated that the airplane was not configured properly. Witnesses agreed that Flight 255’s takeoff roll was longer than normal and the aircraft rotated about 1,200 to 1,500 feet from the departure end of the runway. The pitch angle was noticeably higher than that of other DC–9s, and the tail came close to striking the runway. Only a few witnesses recalled any details about the wing configuration, and most believed the flaps and leading edge slats were extended. Once airborne, the DC–9 began rolling, about 35 degrees left and right. After striking a light pole 2,760 feet beyond the end of the runway, the aircraft rolled left and continued across several rental-car parking lots, striking a second light pole and the roof of a building. It continued rolling, hitting a road and striking a railroad embankment, disintegrating as it went. Numerous fires erupted. One passenger survived; 148 passengers and six crewmembers were killed. On the ground, there were two fatalities, one serious injury, and four minor injuries. The crew The 57-year-old captain was properly qualified with more than 20,000 hours of flight time and more than 1,400 in the DC–9-82. He was described as capable and competent—a pilot who used checklists regularly and “flew by the book.” The 35-year-old FO had more than 8,000 hours and had been flying for the airlines for more than eight years. He had more than 1,600 hours in DC–9-82s. He, likewise, was described as capable

and competent. There were no indications prior to the accident that the crew was less than professional, nor did their training records reveal any weaknesses. The aircraft The DC–9-82 was manufactured in 1981. According to the NTSB, “Examination of the airplane flight and maintenance logbooks did not reveal any discrepancies or malfunctions that would have contributed to the accident.” Its takeoff configuration, under the existing conditions, required the flaps to be set at 11 degrees. The leading-edge slats are automatically extended to an intermediate position, and this configuration was required to provide enough lift for the aircraft to become airborne. The aircraft was equipped with multiple automated systems. According to the NTSB report, “The takeoff warning system is powered by power supply two and is programmed to provide a modulating horn for one second, followed by a voice warning identifying the system or systems, control or controls not properly configured for takeoff. Thus, if the slats are not set for takeoff and the slat takeoff light is not illuminated, the warning system will state the word slats; if the flap handle is not in agreement with the value set in the flap window of the takeoff condition computer, the warning system will state the word flaps.” At the time of the accident, Northwest Airlines procedure required the crew, upon first receiving the aircraft, to test the takeoff warning system. The accident crew received the aircraft in
Height above ground in feet

Flight takeoff paths

800

600

The aircraft was not configured properly for takeoff, which resulted in inadequate takeoff performance.
Plot start at 6,520

Normal takeoff path

400

200 Accident takeoff path 8,000 feet 10,000 feet 41

6,000 feet

Distance from brake release (in feet)
AOPA PILOT •

76 • APRIL 2012

AOPA Pilot Magazine - April 2012

Table of Contents for the Digital Edition of AOPA Pilot Magazine - April 2012