Accident McDonnell Douglas DC-9-32 N3329L,

ASN Wikibase Occurrence # 331007

Date:	Tuesday 8 September 1970
Time:	21:14
Type:	McDonnell Douglas DC-9-32
Owner/operator:	Delta Air Lines
Registration:	N3329L
MSN:	47108/251
Year of manufacture:	1968
Total airframe hrs:	7601 hours
Cycles:	914 flights
Engine model:	Pratt & Whitney JT8D-7
Fatalities:	Fatalities: 0 / Occupants: 94
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Louisville-Standiford Field, KY (SDF) - United States of America
Phase:	Landing
Nature:	Passenger - Scheduled
Departure airport:	Chicago-O'Hare International Airport, IL (ORD/KORD)
Destination airport:	Louisville-Standiford Field, KY (SDF/KSDF)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Delta Air Lines Flight 439 was a scheduled flight from Chicago to Atlanta with intermediate stops at Louisville and Lexington. The DC-9 departed Chicago at 20:13 on an Instrument Flight Rules (IFR) flight plan. At 21:01, Louisville Approach Control established radar contact with Flight 439. Vectors and altitude information were given the crew until the flight was turned to a heading that would intercept the inbound ILS localizer course to runway 29. The flight was subsequently cleared for an ILS approach. Landing weight had been computed to be 92,000 pounds, which established an approach reference airspeed of 123 knots. Flaps had been extended to 50 degrees. When Flight 439 made the approach which terminated in the accident, the high intensity runway lights were set at step 3, medium bright, and the reported flight visibility was 7 miles. Runway 29 did not have a prepared underrun/overrun area. The ground leading to the threshold slopes upward 2deg 44, a gradient of approximately 5 percent. Flight 439 made initial ground contact on this incline 156 feet short of the threshold of the runway, rolled forward 73 feet, and became airborne. The aircraft then contacted the runway 262 feet beyond the threshold and continued to roll/skid on the runway before it came to rest 4,457 feet beyond the threshold. Wreckage examination showed that the fuselage had fractured and buckled in the area between fuselage stations 737 and 794. The tail cone rested on the runway.

PROBABLE CAUSE: "The National Transportation Safety Board determines that the probable cause of this accident was the pilots misjudgment of altitude due to the absence of sufficient lights in the approach area, misleading information produced by deceptive sloping terrain, and that the pilot did not position the aircraft on the ILS glide slope while he was establishing the final approach profile."

Accident investigation: