It may seem obvious that a long-haul flight has caused the condition to develop in a passenger on such a flight, but there are other factors that can have an adverse effect on the circulation.

BBC: Your comments on Economy Class Syndrome

Fortunately, during our flight, that condition stabilized, and we ended up with a situation where all the winds were going in the same direction, all heading east.

ENGADGET: Art Thompson, Red Bull Stratos' technical project director, talks circuit breakers, wind shear and biomedical data

For those who have not, it is a condition of flight in which lift is reduced to such an extent that normal flight ceases and the aircraft becomes a brick.

FORBES: Fiscal Cliff or Not, Is The Economy Already Stalling?

Authorities said the cockpit and flight data recorders were recovered in excellent condition and information from both recorders was consistent with previous reports of the plane hitting a flock of birds before losing power in both engines.

CNN: Investigators find feather, other evidence on downed plane

They will be flown to U.S. facilities in Europe, the official said, and their condition will be assessed on the flight.

CNN: STORY HIGHLIGHTS