Event Details


Title:Loss of roll control, Ozark Air Lines, Inc., Douglas DC-9-15, N974Z, Sioux City Airport, Sioux City, Iowa, December 27, 1968
Micro summary:This Douglas DC-9-15 lost roll control due to ice accretion and eventually crashed.
Event Time:1968-12-27 at 0711 CST
File Name:1968-12-27-US.pdf
Publishing Agency:National Transportation Safety Board (NTSB)
Publishing Country:USA
Report number:NTSB-AAR-1970-20
Pages:42
Site of event:SUX, RWY 35
Departure:Sioux Gateway Airport, Sioux City, Iowa, USA
Destination:Chicago O'Hare International Airport, Chicago, Illinois, USA
Airplane Type(s):Douglas DC-9-15
Flight Phase:Takeoff
Registration(s):N974Z
Operator(s):Ozark Air Lines
Type of flight:Revenue
Occupants:68
Fatalities:0
Serious Injuries:13
Minor/Non-Injured:55
Other Injuries:0
Executive Summary:At approximately 0711 CST on December 27, 1968, Ozark Air Lines Flight 982, a Douglas DC-9, crashed while taking off from the Sioux City Airport, Sioux City, Iowa. There were no fatalities. Among the 64 passengers and four crewmembers, 10 passengers were hospitalized with minor injuries and three crewmembers received serious injuries. The aircraft was destroyed in the crash. There was no fire.

Flight 982 began its takeoff on Runway 35 with the flightcrew aware that ice was present on the wings. The aircraft lifted off and the landing gear was selected to the up position by the first officer. The captain began turning off the landing and taxi lights. As the landing gear began to retract, the aircraft rolled abruptly and violently to the right to an angle of bank estimated by the flightcrew to have reached 900. The captain applied additional power and left rudder in an attempt to level the wings. When no immediate response was noted, he then applied left aileron. With the application of left aileron, the right wing came up; however, the roll continued to the left until the left wing contacted the runway. At this point, the captain discontinued the takeoff. He succeeded in leveling the wings prior to final ground contact, approximately 110 feet beyond the departure threshold of Runway 35. The aircraft came to rest in a grove of trees approximately 1,181 feet beyond the departure end of Runway 35.

At 0657 CST, the surface weather observation at Sioux City was reported as 800 feet overcast with visibility 3 miles. Fog was present and a light, freezing drizzle was falling. The temperature was 22F., the dew point was 20F. and the wind was from 360 at a velocity of 10 knots. At 0714 CST, the only changesreported were that the ceiling had become 700 feet overcast and the wind had shifted to 20 at 13 knots.

The Safety Board determines that the probable cause of this accident was a stall near the upper limits of ground effect, with subsequent loss of control as a result of the aerodynamic and weight penalties of airfoil icing. The flightcrew failed to have the airfoil ice removed prior to the attempted takeoff from Sioux City. The Board also finds that the crew selected an improper takeoff thrust for the existing gross weight condition of the aircraft.

As a result of the investigation of this accident, the Board forwarded three recommendations to the Federal Aviation Administra- tion reemphasizing a previous Board recommendation that flight crewmembers wear shoulder harnesses during all takeoffs and landings, that the security and attachment points of the forward stewardess seat be strengthened in order to reduce the possibility of stewardess injury, and that any potential injurious environmental hazard result- ing from protruding fixtures on equipment in the area of this seat be minimized by relocation or protective padding with high energy absorption material.
Learning Keywords:Operations - Icing
Operations - Uncontrolled Flight into Terrain
Operations - Upset - Uncommanded or excessive Roll
Consequence - Hull Loss

 




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