“after circling over the Atlantic...”
Well, their left turn signal was stuck in the “On” position, what else were they supposed to do?
A flight to Rio from Newark is full of fuel.
They circled to burn and dump fuel, making the plane much lighter before emergency landing. Reduce risk of fire on landing less stress on the plane.
Plus if it was a hydraulic problem possible landing gear or flaps/ speed brakes won’t work properly on landing.