AF447: Should the flight recorder be in the fin?

As a new search effort for the wreck of flight AF447 prepares to set out this week, one of Flight International‘s readers poses the following question in our latest issue:

When I saw a picture of the floating vertical tail of the Air France flight 447 Airbus A330-200 in the Atlantic Ocean, I started wondering if the vertical tail is not a better position for the flight data recorder rather than the rear fuselage?

The reasoning seems sound: in photographs of aircraft wreckage the vertical fin often appears relatively undamaged.

So what’s the catch?

Since recorders are almost always located during accidents on land, vertical fin installation would only really be beneficial if, during a loss at sea, the fin could be located and recovered easily. If the fin sinks with the rest of the wreckage, you’re back to square one.

Retrieved fins make striking media images – think of the Gulf Air, Armavia and XL Airways accidents at sea – and reinforce the impression of fin recoverability, an impression skewed by the absence, obviously, of pictures of unrecovered fins. So the question becomes: how often is the fin usefully retrieved?

French investigation agency BEA, as part of the AF447 inquiry, set up a technical working group which considered the feasibility of installing a lightweight flight recorder – complying with the ED-155 standard – in the vertical fin.

It looked at 26 underwater recovery operations but identified only 20% as having floating tail debris. This led to a crucial conclusion: “The increase probability for retrieving flight and voice data is low.”

fins.JPGIn other words, putting the recorder in the fin is unlikely to improve the chances of recovering it. While the necessary technical maturity exists, said the working group, the proposal also scored poorly in terms of additional costs and weight because the lightweight recorder would complement, rather than replace, those already carried.

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3 Responses to AF447: Should the flight recorder be in the fin?

  1. Paul 12 March, 2011 at 12:03 pm #

    One of the reasons the tail floats is because it is usually largely made from honeycomb material which keeps air in and thus its density low.

    The tail will break off with high velocity impacts, not with fairly ‘controlled’ landings in water. With the second locating the wreckage is usually not that difficult, as the emergency beacons are intact and working and you have a large object to spot. The first one is the one you want the extra recorder for.

  2. Layman 14 March, 2011 at 1:02 pm #

    A better solution would be real-time downloading of the telemetry from the airplane along with GPS information to an airline based groundstation. The advances that have been made over the last decade in terms of broadband speeds, along with data compression technology makes it a more feasible solution.

  3. Gregory Eckersley 28 April, 2011 at 5:31 am #

    Why not put many small hermetically sealed memory chips (eg, flash chips, SD cards or USB sticks) all round the plane (some with plastic foam flotation devices)?

    There seems no reasonable excuse not to have the in-flight data totally and cheaply retrievable in almost any circumstance short of a nuclear bomb.

    It could only be that some vested interests do not want the data to be readily available. Even if there is some valid reason for secrecy, then it could be achieved by encryption rather than by the current armour-plated and nonsensical approach.

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