Everglades National Park, Florida: In the early afternoon on a stormy February day, Northwest Orient Airlines Flight 705, registration N724US, fell into the Everglades roughly thirty-seven miles southwest of Miami International Airport. The Boeing 720 was the first 720 to have been involved in an accident, sending officials from the NTSB (National Transportation Safety Board) into a frenzy to find out if something was wrong with the relatively new plane.
The Boeing 720 was equipped with a CVR (cockpit voice recorder) so piecing the day’s events back together proved to be fairly simple, right up until the point of the crash. There were severe thunderstorms in the area that day, so air traffic controllers vectored the jet airliner out on a southerly route, instructing the flight to fly south, then loop over the storms, seeking out a stable route through the storm. Pilots radioed that they did indeed see a pathway through the storms, but advised the ATC to offer other flights a different route, as the one that they chose was closing quickly.
The FDR along with the transmissions from the crew pieced together a roller-coaster ride for the flight before it plummeted to the swamp below, taking all 43 souls with it. The flight data recorder measured climbs at a rate of 9,000 feet per minute and g-forces ranging from 1.5 to -2.8. When the plane suddenly dove below 10,000 feet, the forward fuselage broke free from the rest of the plane from the incredible stresses that had been put upon the airframe. The forward fuselage broke upward, peeling back along the top of the cabin, while the vertical stabilizer broke free and fell of the port side of the craft. Investigators found that all four engines had broken free during the fall and were scattered around the debris zone.
The NTSB finally reported that the plane came down because of the interaction between the plane and severe vertical air drafts and large longitudinal control displacements, also known as severe turbulence.