Flight 710 was a regularly scheduled flight departing Minneapolis-St. Paul to Miami with a stop at Chicago Midway Airport. Radio contact with the Indianapolis Control Center was made at approximately 3:00 pm local time. About 15 minutes later, witnesses reported seeing the airplane break into two pieces with the right wing falling as one piece and the remainder of the craft plunging to earth near Cannelton in southern Indiana. At the time, investigators organized by the Civil Aeronautics Board worked on three major theories:
That a bomb blew up the plane and its passengers and crew members as they passed over southern Indiana on a Chicago-to-Miami flight.
That violent air turbulence could have destroyed the craft, the first Electra purchased by Northwest and in service only seven months. Such turbulence was reported over southern Indiana at about the time of the crash.
That the plane disintegrated through metal fatigue which had recently caused other crashes of high-speed airliners. The crash was the third Electra disaster in a little more than a year and the third unexplained accident in four months. It came within days of the Washington hearings on the death of 34 people in a National Airlines plane crash near Bolivia, North Carolina.
"Obviously, this plane broke up in the air," CAB spokesman Edward Slattery said at the time. "It is too early to tell the cause of the tragedy, but we will investigate all possibilities, including a bomb." The New York Times reported that at 5:44 P.M., an hour and a half after news of the crash in the snow-covered Indiana-Kentucky border country, an anonymous caller told the Chicago police that a bomb had been placed aboard a plane at Midway Airport. The police searched the airport, but found nothing and said that they were convinced the call was a prank. The operator said she thought the caller was a young teenager. The craft's fuselage plunged into an Ohio River country farm at a speed of over 600 miles per hour and disintegrated. The Federal Bureau of Investigation sent agents to the scene to determine whether there was any violation of federal law. Such an investigation would include the possibility of sabotage. State Police Sgt. Joe O'Brien said that the plane was last heard from over Scotland, Indiana, about from the crash site. He said the pilot, Capt. Edgar LaParle, had reported rumble and the weather was very muggy and cloudy. So much wreckage rained over a wide area, as the plane came apart in the air, that it was first believed that two planes had collided. However, the Federal Aviation Agency and the State Police said that all the pieces they could find were from one plane — Northwest's Lockheed Electra Flight 710. A wing and two engines of the wrecked turboprop were found about five miles from the place where the plane's fuselage hit. Almost nothing was left of the craft. Hours after the crash, a column of blue-gray smoke still rose from the crater, about deep and wide. NASA, Boeing and Lockheed engineers determined that the probable cause for the accident was in-flight separation of the right wing while cruising at due to flutter caused by unexplained reduced stiffness of the engine mounts. This was subsequently defined as "whirl mode." Six months earlier, a Braniff International Airways L-188 Electra, Flight 542, disintegrated over Buffalo, Texas at, killing all on board. This second similar crash moved the Federal Aviation Administration to immediately issue a reduced cruise speed directive while investigators tried to determine the cause of the fatal crashes.
The citizens of Perry County and the Cannelton Kiwanis Club raised funds for a memorial at the site of the 1960 crash. Dedicated in 1961, the Kiwanis Electra Memorial marks the site. It is located on Millstone Road, which may be reached via Indiana highways 66 and 166, eight miles east of Cannelton in Tobin Township. Cannelton newspaper editor and civic booster Bob Cummings wrote the words which are inscribed on the memorial along with the names and symbols of the religious faiths of those who died aboard the plane. The inscription reads: "This memorial, dedicated to the memory of 63 persons who died in an airplane crash at this location, March 17, 1960, was erected by public subscription in the hope that such tragedies will be eliminated."
