The Air France Flight 447 crash, considered one of the worst aviation disasters in history, could have been avoided, a top-ranking aviation safety expert said.
"Absolutely, this accident didn't have to happen," said William Voss, the president and CEO of the Flight Safety Foundation.
BEA, the French government's official accident investigators, conducted a three-year investigation into the crash, which killed all 228 people on board, including one married couple from Louisiana, when the Airbus A330 slammed into the Atlantic Ocean off the coast of Brazil in 2009.
In the agency's final report, which was released today, investigators determined that a combination of technical failures and mistakes made by inadequately trained pilots was responsible for the crash. They recommended that pilots be better trained to manually fly commercial aircraft at high altitudes and called for stricter plane certification rules.
"Our investigation is a no-blame investigation. It is just a safety investigation," Jean-Paul Troadec, the director of BEA, told ABC News. "What appears in the crew behavior is that most probably, a different crew should have done the same action. So, we cannot blame this crew. What we can say is that most probably this crew and most crews were not prepared to face such an event."
But the report went on to say that there were at least 12 other instances where pilots encountered this issue and the flights continued normally without problems. Voss said the Air France pilots didn't seem prepared for the situation they found themselves in the night of the crash.
"[The pilots] seemed to have trouble looking past the automation they were accustomed to and not really able to continue with the old raw information that pilots used to depend on," he said. "Clearly the report shows that there was a lot of difficult communication on the flight deck, a lot of incomplete thoughts, a lot of confusion."
According to the report, a speed sensor on board the plane, called a pitot tube, stopped functioning after becoming clogged with ice at high-altitude while the plane was flying through a thunderstorm. This caused the auto-pilot to disengage and shift the controls back to the pilots. While flying in heavy turbulence, the pilots failed to properly diagnose the severity of the problem because the pitot tube, a critical piece of equipment to the aircraft, was sending inaccurate data to the cockpit, the report said. The pilots put the plane into a devastating stall and it fell rapidly from the sky, before pancake-ing into the ocean.
"Despite these persistent symptoms, the crew never understood that they were stalling and consequently never applied a recovery maneuver," the report said.
Investigators noted that there was no possibility of surviving the accident.
"The crew's failure to diagnose the stall situation and consequently a lack of inputs that would have made it possible to recover from [the accident]" was a contributing factor, it concluded.
Airbus said in a statement to ABC News that it has been working to improve the pitot tubes and is taking measures to avoid such accidents in the future. Air France also has stressed the equipment problems and insisted the pilots "acted in line with the information provided by the cockpit instruments and systems. .... The reading of the various data did not enable them to apply the appropriate action."
Air France Flight 447 was en route from Rio de Janeiro to Paris on May 31, 2009 on an overnight trip when it vanished. The plane crashed into the Atlantic Ocean in the early morning hours of June 1, 2009 -- nearly four hours after take-off.
As "Nightline" previously reported, black box tapes recovered from the wreckage in April 2011 revealed that almost four hours into the flight, the plane was 800 miles off the coast of Brazil, and Captain Marc Dubois left the cockpit for a scheduled nap. At the time, the plane was about to fly into a thunderstorm, one that other flights that night had steered around.
According to the tapes, First Officer Cedric Bonin, a 32-year-old pilot who had fewer than 5,000 flight hours under his belt, was at the controls but had never been in this situation before at high-altitude. Bonin made the fatal mistake of pulling the plane's nose up, which caused it to go into a deep stall.
As Flight 447 went deeper into its catastrophic stall, the stall alarm cut in and out intermittently, the black box tapes revealed. Airbus had previously claimed the stall alarm on Flight 447 "was performing as designed," but critics charged the pilots would have been confused by the mixed signals.
It was not until the final three seconds before the plane hit the Atlantic that the pilots even realized they were going to crash, the black box tapes revealed.
About 180 victims' family members have sued Air France and Airbus over the crash. The family of one of the victims, Eithna Walls, has settled its lawsuit.
The A330, considered among the safest in the skies, has flown over 800 million passengers across the world and there are 865 planes in operation today, according to Airbus's website. But in modern aviation, large commercial jets almost fly themselves. Voss said that on any given flight, pilots are manually flying the plane for only three minutes -- one minute and 30 seconds each for take-off and landing.
"The fact is there aren't many opportunities for a pilot to hand fly the aircraft anymore," he said. "The truth is it's only a few minutes during each flight, maybe until they climb up to altitude. Many airplanes don't even allow the hand flying for that long."
At the heart of the heated debate over so-called "automation addiction," which is when pilots are overly dependent on computers to fly their planes, is the question of whether pilots are actually learning how to properly fly large commercial aircraft.
"Because of this sophistication and the ability of airplane to fly themselves, they don't have as many people to actually fly the airplane, to actually exercise their stick and rudder capabilities," Bill Bozin, the vice president of safety and technical affairs at Airbus, told "Nightline" in June.
In the wake of the Air France crash, Voss said "many airlines" were retraining their pilots on flying manually, but that much more needs to be done to overhaul pilot training programs around the world.
"I think there's a training gap that still exists," he said. "There have been hundreds of incremental changes to the way we fly aircraft but there haven't been any changes in the training program that reflect that."
"The fact is aircraft are going to become more automated," Voss added. "There's no way to even tell how many lives have been saved by the automation that are in aircraft. So it's a good thing and it's going to continue to progress. What we have to continue to do is keep the human side up to speed with what the automation is doing."