From: firstname.lastname@example.org (Mark Brader) Organization: SoftQuad Inc., Toronto, Canada Date: 07 Mar 96 02:04:43 References: 1 2 Followups: 1 2
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Robert Ashcroft (rna@gsb-birr.Stanford.EDU) wrote: > > News item in the newspaper today (Feb 16) said that the flight > > recorder from the Alas/Birgenair 757 had been located on the seabed... John Bay (email@example.com) writes: > Would it be possible to make a flight recorder that would transmit all > its stored data upon request, thereby eliminating the necessity to > physically recover the box? This is unlikely to be an issue for a crash on land, so I assume we're talking about the ocean (or a big lake), as with this particular crash. In that case, the same problems would be faced that submarines have in communicating when submerged. Water is practically opaque to radio waves, and while it will transmit sound waves, they get distorted over long distances. I wonder if it might be feasible, though, to attach something to the recorders to make them easier to recover in case of a crash into water. I'm thinking of two possibilities. One is a sonic beacon, to be audible from a passing submarine, or a hydrophone on a surface ship; that ought to cut the search time quite a bit. To activate it in the case of a crash into water, a pressure-sensitive switch could be used -- to trip when the ambient pressure reaches, say, 3 atmospheres, indicating that the device is about 65 feet (20 m) underwater. But the beacon would need battery power, and to be heard at a sufficient distance, maybe more power than it's feasible to provide. The second idea is a float. Attach to the recorder a sturdy, brightly colored balloon and a bottle of a suitable compressed gas. Again trip on a high ambient pressure, being sure to provide enough gas to inflate the balloon against that presssure. This apparatus could be entirely mechanical, so power is not an issue. A drawback is that it might not work -- the crash must destroy the plane sufficiently that the recorder and balloon can float free. (I have no idea how firmly the recorders are fastened down in normal operation, I must admit.) But if they don't, well, we're no worse off than we would be today. -- Mark Brader \ "The occasional accidents had been much overemphasized, firstname.lastname@example.org \ and later investigations ... revealed that nearly 90% SoftQuad Inc., Toronto \ ... could have been prevented." --Wiley Post, 1931 My text in this article is in the public domain.