Thursday, June 4, 2009

Air france tragedy

As we have all heard by now, Air France went down in Atlantic few days back on its way to Paris from Rio. 228 people all dead. Was it bad weather... complete failure of electrical systems, it seems no one will ever know as from the media reports it appears that it is highly unlikely to locate the black box considering that it may be at the bottom of the Atlantic Ocean or stuck in the mountainous region in that part part of the Atlantic. This made me think why don't they make black box to be floatable. I googled it and came across the following:

Particularly, I found following reply from a person named "propman" quite relevant:

Cockpit Voice Recorders (CVR) and Flight Data Recorders (FDR) would certainly be easier to locate if they floated but there are serious engineering problems to overcome. The recorders are usually located in the rearmost compartment, near the centerline of the fuselage and as such is surrounded by the structure of the aircraft. This is done to provide the recorders with as much mechanical protection as possible in a crash. The recorders can also record up to several dozen (in the case of FDRs) channels of information. This means the electrical connectors are very large and require a bit of work sometimes to disconnect. The recorders are also big and heavy. 

In order to separate the recorder from the aircraft would require some mechanical means to eject the unit from the aircraft during the beginning of the impact event, before the tail structure became distorted. The “Launching Charge” must not present any danger of starting a fire and be powerful enough to push the recorder a safe distance from the plane. Think of an scaled down ejection seat, only pushing against a heavy steel box. The box would still be heavy since it would need to suvive the crash in case it didn't eject. The electrical connectors must also release instantly, completely and reliably. Perhaps just cutting the wires with a squib charge.

Now we have to get the box to float. Floatation foam is simple enough, but the shear volume required would make an already unwieldy box even more difficult. Perhaps a self inflating bag, like a life vest? That may work. And if the box is floating, an Emergency Locator Beacon (ELT) would assist in locating it. The recorders are already fitted with a device for finding it if it sinks. This device is called an Underwater Locator Beacon (ULB) and is NOT part of the recorder but is separate and located on the outside of the recorder case attached by brackets.

There we have it: Recorders that jettison from aircraft during impact and float.

So why don’t we have them?

The answer is MONEY.

To design such a system and maintain it would not only cost a large amount of money, but that cost would provide a disproportionate cost-benefit. That is to say it’s not worth it. The purpose of the recorders is to assist in crash investigation but they are not the only source of information and as such are nice to have but not absolutely necessary.. Besides, there have been recorders that have been recoverable in water crashes by other means. Very few have been ‘lost’.

Perhaps in the future we may have a palm sized combination CVR-FDR that weighs mere ounces and be mounted on top of the rudder under plastic film.... 

Hmmmm……Maybe……..But not today.


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