Air France Airbus A330-200 crash: Wreckage, sensory equipment recovered on local shores

Jul 17, 2009 News

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By Gary Eleazar
Dennis Baksh, a farmer from Ann’s Grove, East Coast Demerara, knew that he had stumbled on to something valuable last Friday whilst on the Hope Beach.
Baksh had found what is believed to be a part of the fuselage and a component believed to be the first piece of sensory equipment recovered from Air France Airbus A330-200 that crashed into the Atlantic Ocean after leaving neighbouring Brazil en route to France on June 1.
According to Baksh, he immediately realized that what he had found was not a part of a boat and as such made arrangements to have a tractor haul the piece of debris to his home, some distance inland.
“I see it pun deh seawall and when a go and check I say that this got to be a part of a plane,” said Baksh, yesterday.

The man who made the important discovery said that he did not see any other piece of debris in the area.
The sensory component that was attached to the fuselage is a three-axis Inertial Measurement Unit (IMU) which is cylindrical in shape and is mounted on a flat base with electrical wiring protruding from within it. It bears the trademark ‘Sensorex.’
Baksh attempted to open the device but only managed to break into the cylindrical case; the cube within was impenetrable to Baksh.
A GCAA official said that he noted the numbers on the fuselage and on the equipment marked Sensorex and that he would be forwarding these to the relevant authorities.
Another aviation official explained that the piece of equipment marked Sensorex might be the first piece of sensory equipment retrieved from the crashed plane. He explained that it sends signals to the flight panel and this might be the piece of malfunctioning equipment that caused the crash.
An Inertial Measurement Unit (IMU) is the main component of inertial guidance systems used in air, space, and watercraft, including guided missiles.
An IMU works by sensing motion including the type, rate, and direction of that motion using a combination of accelerometers and gyroscopes.
The data collected from these sensors allows a computer to track a craft’s position, using a method known as dead reckoning.
The IMU works by detecting the current rate of acceleration, as well as changes in rotational attributes, including pitch, roll and yaw.
The data is then fed into a computer, which calculates the current speed and position, given a known initial speed and position.
For example, if an IMU installed in an airplane were to detect that the craft accelerated westward, resulting in a calculated, constant speed of 500 miles per hour, and detected no other accelerations for one hour, then the guidance computer would deduce that the plane must be 500 miles west of its initial position.
When combined with a computerized system of maps, the guidance system could use this method to show a pilot where the plane is located geographically, similar to a GPS navigation system but without the need to communicate with any outside components, such as satellites.
The term IMU is widely used to refer to a box containing three accelerometers and three gyroscopes. The accelerometers are placed such that their measuring axes are orthogonal to each other. They measure inertial acceleration, also known as G-forces.
Three gyroscopes are placed in a similar orthogonal pattern, measuring rotational position in reference to an arbitrarily chosen coordinate system.
IMUs are primarily used in vehicle-installed inertial guidance systems. Today almost every commercial or military water-going vessel has one.
Most aircraft are also equipped with IMUs.

When Baksh found the piece of fuselage, he said that there was also a thick foam-like material attached to the inside of the piece of fuselage but this he removed given that while it was water soaked it made the already heavy piece of debris almost immovable.
The Police and the Guyana Civil Aviation Authority were subsequently contacted with the latter confirming that the piece of debris was definitely from a large aircraft and that the component bearing the trademark Sensorex was indeed a piece of sensory equipment used on aircrafts.
The Brazilian Embassy was also contacted.
At present, it is still unclear what caused the crash that killed 228 persons aboard.
The aircraft was flying in turbulent weather at the time but some international analysts have said it is unlikely that the weather contributed to the crash but are not ruling it out completely.
Chief Air France spokesman Francois Brousse had suggested the plane could have been struck by lightning but most experts say lightning doesn’t usually bring down a modern airliner, unless it coincides with other factors that contribute to the accident.
“Planes are built with lightning strikes in mind and are struck reasonably frequently,” according to Patrick Smith, a U.S. commercial pilot and aviation writer.
Aviation safety statistics indicate that each large passenger jet such as the Airbus A330 is struck by lightning about once every three years on average.

Regional aircraft, however, which fly at lower altitudes, are hit more frequently, about once a year.
About seven hours after taking off and flying through the night over the mid-Atlantic, the pilots of the Air France Airbus reported that they had encountered an area of intense cumulonimbus activity, part of the massive thunderstorms that regularly batter the region
Air France reported that the aircraft’s ACARS (Aircraft Communications and Addressing System) a digital datalink that automatically transmits service messages from the aircraft to ground stations messaged the company’s headquarters regarding a problem with the aircraft’s electrical and pressurization systems.
The French aircraft accident investigation agency, the Bureau d’Enquetes et d’Analyses (BEA) had announced that an examination of structural components of the aircraft recovered from the surface of the ocean revealed that they were deformed from the bottom to the top.
This according BEA suggests that the aircraft hit the sea “in the direction of flight and with a sharp vertical acceleration”. This, in turn, indicates that the aircraft was “not destroyed in flight”. The aeroplane’s speed sensors were “a factor but not the cause” of the disaster.
The investigators had also determined that no distress call was made, either to air traffic control or to other aircraft.
The most direct evidence of the cause of the accident is the presence of suspected aircraft debris on the ocean surface and a series of 24 automatically generated maintenance messages that were transmitted from the plane shortly before the crash.
Investigators also said that messages indicated that cabin pressure was lost and there was some kind of electrical system failure.
Following the crash a massive search was launched by the Brazilian Military as well as from France.

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