|Title:||Landed short, Eastern Air Lines, Inc., Boeing 727-100, N8168G, Flight 9701, Atlanta, Georgia, December 21, 1971|
|Micro summary:||This Boeing 727-100's autopilot contributed to an unstabilized approach and collision with the approach lights short of the runway.|
|Event Time:||1971-12-21 at 0448 EST)|
|Publishing Agency:||National Transportation Safety Board (NTSB)|
|Site of event:||Short final, approach lights, runway 9R|
|Departure:||Charlotte-Douglas International Airport, Charlotte, North Carolina, USA|
|Destination:||William B. Hartsfield International Airport, Atlanta, Georgia, USA|
|Airplane Type(s):||Boeing 727-100|
|Operator(s):||Eastern Air Lines|
|Type of flight:||Revenue|
|Executive Summary:||Eastern Air Lines, Inc., Flight 9701 of December 21, 1971, a Boeing 727-100, N8168G, was a scheduled cargo flight from Charlotte, North Carolina, to Atlanta, Georgia. The flight was routine until the aircraft arrived over the outer marker of the instrument landing system serving Runway 9 Right at the William B. Hartsfield Atlanta International Airport.|
An instrument landing system approach to Category II minima was initiated with the automatic pilot and approach coupler engaged. The landing flaps were extended to the 30' position when the aircraft passed over the outer marker. During flap extension, the aircraft deviated from the glide-slope centerline and did not again become stabilized on the glide-slope until it was at an altitude of approximately 800 feet above ground level. At 225 feet above ground level, the aircraft again deviated from the glide slope and began a descent that continued until the landing gear struck the Nos. 18, 17, 16, and 15 bars of the approach light system. The aircraft remained airborne, however, and it was landed successfully on Runway 9 Right.
Contact with the light system structure ruptured the left main landing gear tires, and caused minor damage to the left wing flaps. The approach light system was rendered inoperative because of substantial damage to the four light bars.
The National Transportation Safety Board determines that the probable cause of this incident was an unexpected and undetected divergence of the aircraft from the glide-slope centerline induced by a malfunction of the automatic pilot. This divergence occurred at an altitude from which a safe recovery could have been made. However, both the pilot and the first officer were preoccupied at the time with establishing outside visual reference under visibility conditions which precluded adequate altitude assessment from external clues. Consequently, the pilot did not recognize the divergence from the glide-slope in time to avoid contact with the approach lights.
|Learning Keywords:||Operations - Crew Resource Management|
|Operations - In-flight Collision with Ground Structure|
|Operations - Runway Underrun|
|Systems - Autopilot/Autothrottle|
|Systems - Flight Controls - Spoilers - Slats - Flaps|
|Systems - Landing Gear|
|Systems - Landing Gear - Tires|
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