For two years, the cause of crash of Air France flight 447 eluded investigators.
It went down off the coast of Brazil, on its way from Rio de Janeiro to Paris, killing all 228 people on board, in June 2009.
French authorities released a report Friday based on readings from the "black box" flight recorders found on the ocean's floor.
The report describes "the last 3 minutes 30 seconds of that flight as the plane drops from 38,000 feet in that period of time directly onto the ocean," CBS News Travel Editor Peter Greenberg said on "The Early Show" Friday.
"Now," he told co-anchor Chris Wragge, "what's happening is they're flying initially at their regular flight altitude of 35,000 feet when they encounter some turbulence. At this point, the plane is on auto-pilot, but their flight sensors ... which actually tell the pilots how fast they're going, apparently are frozen. They're not working. They're defective.
"So what do the pilots do? What pilots normally do: They try to slow the plane down, they disengage the autopilot, they disengage their auto-thrust, and they basically slow the plane down. Now they're in trouble, because they're slowing the plane down, slower than it really should be flying at all, and they put it into a high-speed stall. The nose goes up to about 16 degrees, and the plane starts climbing. But at that altitude and that speed, it loses speed very quickly and -- guess what? At 38,000 feet, it starts to drop, and it's dropping at some points up to 10,000 feet a minute."
So, Wragge surmised, "It's these speed sensors that really threw the pilots (off), because they were getting incorrect speed readings?"
"From the beginning. Yes," Greenberg confirmed.
Is this a systemic problem with Airbus A-330s?
"The investigators have been looking at these speed sensors for quite some time" Greenberg pointed out. "In fact, this past March, Air France was charged in a French court with manslaughter in the deaths of these 228 people. That investigation is continuing. Now, they've since fixed those and they've since adjusted those. But ... the charge was, did Air France know they were defective when that plane was already flying?"
The report says the pilot wasn't in the cockpit when the trouble began, but Greenberg says that's "not relevant at all to the situation because, in any flight that's of this duration, you always have relief pilots, and the main pilot was doing his crew rest (getting rest). He did come in. (He) never took (the) controls again, because they were already in control of the plane. At least they thought they were. And at that point, all they could do was try to get speed up. Because they were losing speed and losing altitude. They tried to put the nose down, but they couldn't control the descent and, 3 minutes 30 seconds later, they impacted the ocean."
And what was happening to the plane itself during all this?
"Very little at this point that we know of. We just know that, with those instruments frozen, all their instruments in the cockpit were no longer of use to them. They were not getting any relevant readings that they could do anything about."
The investigation is far from closed, Greenberg stressed. "There's one open area. And that's the location and the condition of the tail of that plane. That tail of that plane was found many, many, many miles away from the main debris field and it was found intact. The real question is -- did that tail come off before the plane hit the water? And when did it come off if it came off at all? That's what they're going to look at now."