52 Years ago today: On 9 September 1969 an Allegheny Airlines DC-9 collided with a Piper PA-28 and crashed near Shelbyville, killing all 82 occupants of the DC-9 and the Piper pilot.

Date:Tuesday 9 September 1969
Time:15:29
Type:Silhouette image of generic DC93 model; specific model in this crash may look slightly different
McDonnell Douglas DC-9-31
Operator:Allegheny Airlines
Registration:N988VJ
MSN:47211/357
First flight:1968
Total airframe hrs:3170
Engines:Pratt & Whitney JT8D-7
Crew:Fatalities: 4 / Occupants: 4
Passengers:Fatalities: 78 / Occupants: 78
Total:Fatalities: 82 / Occupants: 82
Collision casualties:Fatalities: 1
Aircraft damage:Destroyed
Aircraft fate:Written off (damaged beyond repair)
Location:6,5 km (4.1 mls) NW of Fairland, IN (   United States of America)
Phase:En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Cincinnati/Northern Kentucky Airport, KY (CVG/KCVG), United States of America
Destination airport:Indianapolis-Weir Cook Municipal Airport, IN (IND/KIND), United States of America
Flightnumber:853

Narrative:
Allegheny Airlines Flight 853 was a regularly scheduled flight from Boston, Massachusetts, to St. Louis, Missouri, with intermediate stops at Baltimore, Maryland, Cincinnati, Ohio, and Indianapolis, Indiana. The flight proceeded routinely to Cincinnati from where it departed at 15:15 hours local time.
An IFR clearance was received to Indianapolis via airway V-97 at an altitude of 10,000 feet.
At 15:22 the Indianapol1s Air Route Traffic Control Center (ARTCC) controller advised, “Allegheny e1ght fifty three is in radar contact, cross Shelbyville (VOR) at and maintain six thousand and your position now thirty-two miles (unintelligible) … southeast of Shelbyville.”
Approximately 3 minutes later, the flight reported leaving 10,000 feet, and during its descent, was instructed to contact Indianapolis Approach Control. At 15:27, the approach controller advised,
“Allegheny eight five three roger, squawk ident heading two eight zero radar vector visual approach three one left.” Allegheny 853 acknowledged the vector and was, almost immediately instructed to descend to 2,500 feet. The flight acknowledged at 15:27:29, “Eight five three cleared down two thousand five hundred and report reaching.” This was the last recorded transmission from the flight.
At the same time a Piper PA-28-140, N7374J, was operating in the area on a solo training flight from Brookside Airpark, Indiana, to Bakalar Air Force Base. The aircraft was on a VFR flight plan indicating a cruising altitude of 3,500 feet. The pilot advised the Indianapolis Flight Service Station at 15:21 that he had departed Brookside, requesting activation of his flight plan. This was the last known communication with N7374J.
The approach controller did not notice any conflicting traffic in the area of Allegheny 853. Yet both aircraft were on a converging course, with the DC-9 descending towards the altitude of the PA-28.
After the DC-9 broke through the clouds, both flights had a window of 14 seconds to see and avoid. The NTSB determined that the captain, from his position, was unable to see the Piper. The first officer was likely monitoring the altimeter in preparation for a 3500 feet altitude call. Two seconds after this call, both aircraft collided. The initial impact between the two aircraft occurred at the forward upper right side of the vertical fin just below the horizontal stabilizer, of the DC-9, and the left forward side of the PA-28, just forward of the left wing root.
The horizontal stabilizer of the DC-9 broke off and the aircraft impacted the ground inverted, almost wings-level, in a nose-down attitude. The Piper broke up and crashed about 4500 feet from the DC-9. All 82 occupants of the DC-9 and the pilot of the PA-28 were killed.

Probable Cause:

PROBABLE CAUSE: “The deficiencies in the collision avoidance capability of the Air Traffic Control (ATC) system of the Federal Aviation Administration in a terminal area wherein there was mixed Instrument Flight Rules (IFR) and Visual Flight Rules (VFR) traffic. The deficiencies included the inadequacy of the see-and-avoid concept under the circumstances of this case; the technical limitations of radar in detecting all aircraft; and the absence of Federal Aviation Regulations which would provide a system of adequate separation of mixed VFR and IFR traffic in terminal areas.”