"The oscillation of roughly 15 to 20 seconds is a telltale sign that suggests the M.C.A.S. system may have been involved, said R. John Hansman Jr., a professor of aeronautics and astronautics at the Massachusetts Institute of Technology.
"Planes like the Boeing 737 oscillate naturally, he said, because of turbulence and and other effects. But those swings have different time spans: either between five and eight seconds, or a minute or longer. The variations in the intermediate range of 15 or so seconds have no other obvious explanation, he said."
Both planes porpoised with periods of~20 seconds during their flight.
"Planes like the Boeing 737 oscillate naturally, he said, because of turbulence and and other effects. But those swings have different time spans: either between five and eight seconds, or a minute or longer. The variations in the intermediate range of 15 or so seconds have no other obvious explanation, he said."
Both planes porpoised with periods of~20 seconds during their flight.