Off the coast of Brazil, search teams continue to hunt for the wreckage of Air France Flight 447. They have recovered 41 bodies so far, with 187 still not accounted for. The cause of the crash remains a mystery, but investigators are focusing on what could have been faulty speed sensors.

The scene was somber as Brazilian helicopters began shuttling bodies recovered from the crash.

First to a Brazilian island and then to the mainland.

Investigators will now begin the difficult process of identifying the victims and studying their injuries. This could give clues to what caused the May 31 crash that killed all 228 people onboard.

Meantime, a labor union representing some Air France pilots urged colleagues to refuse to fly unless their planes are equipped with new and improved speed sensors.

"We have asked our colleagues to make sure that on the Airbus, long flights, to make sure before taking off that at least two out of the three sensors have been modified," said Bruno Sinatti, Alter Union President.

Another pilots' union said Tuesday that Air France has agreed to that.

The older sensors on flight 447 fed inconsistent information on speed to the plane's computers, possibly causing the aircraft to break apart over the Atlantic.

Air France had begun replacing the older sensors on some of its Airbuses, but not on Flight 447.

"The only question we have is why these sensors that showed signs of weakness a while ago, why the improvements which were proposed by the manufacturer were not done by Air France," added Mr. Sinatti. "Only Air France can respond to that."  

In the vast Atlantic, the search for bodies and debris continues. A large piece of the plane's tail, just recovered, may steer searchers closer to the all-important data recorders that could provide crucial information.

The US navy is sending two sonar devices that could pick up the pings made by the so called black boxes.  

A French nuclear submarine will also search for the data recorders.

In just three weeks, the beacons on the boxes will begin to fade.