Blocked static port

A blocked static port is a more serious situation because it affects all pitot-static instruments.[6] One of the most common causes of a blocked static port is airframe icing. A blocked static port will cause the altimeter to freeze at a constant value, the altitude at which the static port became blocked. The vertical speed indicator will become frozen at zero and will not change at all, even if vertical airspeed increases or decreases. The airspeed indicator will reverse the error that occurs with a clogged pitot tube and cause the airspeed be read less than it actually is as the aircraft climbs. When the aircraft is descending, the airspeed will be over-reported. In most aircraft with unpressurized cabins, an alternative static source is available and can be toggled from within the cockpit of the airplane.[6]

The French Bureau of Investigations and Analysis said the memory unit of the flight data recorder was found early Sunday and brought to the surface, although it will be more than a week before it can be examined.

Investigators were initially disheartened last week when an underwater drone located the recorder’s protective housing without the cylindrical memory module attached.

But on Sunday, the mood at the bureau’s headquarters was charged with anticipation.

“This is a very happy surprise,” Jean-Paul Troadec, the bureau’s director, said in an interview.

Investigators had said the memory unit was probably dislodged from the housing when the plane hit the water, making it less likely that it would be found amid the rest of the wreckage, on a sandy plane nearly two and a half miles below the surface. “We had been expecting a lengthy search,” Mr. Troadec said.

Photos of the memory module showed that it had suffered little exterior corrosion, he said, though it was not clear whether the memory chip inside had been damaged. If it is still readable, it could provide critical information on the plane’s position, speed, altitude and direction when it ran into trouble.

“First we need to know if we can read it,” he said.

An Air France jet that crashed into the Atlantic Ocean two years ago stalled three times before plunging into the sea, killing all 228 people on board, information from the plane's flight recorders shows.

French investigators said on Friday that data from the devices, known as black boxes, revealed the final minutes of the air disaster, with two co-pilots struggling to regain control of the Airbus jet.

The emergency began with a stall warning two and a half hours into flight 447 between Rio de Janeiro and Paris on June 1 2009.

The captain was on a routine break at the time and was summoned back to the cockpit by the second and third in command, but did not retake the controls.

The co-pilots wrestled with the plane's controls for three and a half minutes as it descended rapidly, falling 3,350 metres per minute, rolling from left to right and finally plunging into the Atlantic.

"There was an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS), the French Bureau of Inquiry and Analysis (BEA), said.

"This lasted for less than one minute".

However the investigators said it is still too early to give the causes of the crash, and a full report is expected to be released this summer.

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