Faulty Pitot tubes—speed sensors that are crucial for auto-pilot navigation—surfaced as one of the leading theories explaining why Air France 447 crashed in 2009. The latest black box analysis confirms that invalid readings were provided right before the plane crashed.

According to CNN, France's Bureau of Investigation and Analysis says the sensors gave readings inconsistent with the plane's standby sensors, causing the Airbus A330 to stall at 38,000 feet and fall from the sky. And though both pilots were in the cockpit at the time of the stall, investigators are confused why they tried to pull the nose up, instead of down, to recover from the stall. [CNN]