[6] Prior to departing from Miami in the early afternoon, the Northwest Orient flight crew questioned the ground controller at the airport about the departure routes being used, and the controller replied that most flights were departing "either through a southwest climb or a southeast climb and then back over the top of it.

"[7] After the Boeing 720 lifted off from Runway 27L, helmed by captain Roy Almquist,[8] it made a left turn, based on radar vectors from Miami Departure Control, to avoid areas of anticipated turbulence associated with thunderstorm activity.

While maintaining 5,000 feet (1,500 m) and a heading of 300 degrees, Flight 705 contacted controllers and requested clearance to climb to a higher altitude.

There were communication difficulties, although after the jet was provided with a different frequency to use, the flight crew established contact with Miami ARTCC.

This caused the airspeed to drop from 270 to 215 knots (311 to 247 mph; 500 to 398 km/h), which prompted the captain to apply full nose down elevator and trim.

All four engines generally separated before the debris of the aircraft fell in an unpopulated area of the Everglades National Park, 37 miles (60 km) west-southwest of Miami International Airport.

The negative Gs caused by the pitchdown would have lifted the pilots from their seats, blurring their vision and making them unable to hold the yoke, which was in the full forward position due to the increased sensitivity.