3 ms·

Battery life ... I think the 30 days figure is the minimum spec, but in reality it can go on longer, depending on age of battery, i.e. when it was last replaced

by damian2000 12y ago

Battery life ... I think the 30 days figure is the minimum spec, but in reality it can go on longer, depending on age of battery, i.e. when it was last replaced.

cnvogel 12y ago
This video has a teardown of an old flight data recorder (tape based), with a ultrasound pinger/locator beacon(at about 3 minutes into the video). http://youtu.be/mQehX0rVYuY?t=3m48s http://youtu.be/mQehX0rVYuY?t=3m48s Here's some technical information about this particular beacon. http://www.sea-avionics.com/lc/cart.php?target=productDetails&model=DK-100&substring=DK-100 http://www.sea-avionics.com/lc/cart.php?target=productDetail... It says that the shelf-life of the battery is only 6 years (which probably means that it will lose some significant part of its total capacity over 6 years). Having a device operate for "decades" surely will need different power sources. (even if cutting down on average power consumption drasticly, by only emitting one ping per week or so...)
- leoc 12y ago
  Sure, but exponential slowdown over maybe six months seems achievable, and would likely have been very useful in the case of MH370.
  - mikeash 12y ago
    I think it just comes down to this being an extremely conservative field, and these systems get implemented based on past experience. Before MH370, basically nobody anticipated having to search for a commercial airliner with no idea where it went besides that it was vaguely somewhere within a continent-sized patch of ocean. The 30-day period was considered to be enough. Even with MH370 it could have been enough if the Malaysian authorities hadn't been so unbelievably incompetent as to waste an entire week searching the wrong ocean when they had data which definitively showed it went elsewhere. It's similar to the question of why airliners don't periodically report their position using GPS and satellite data, since they basically have the capability already. The answer is that nobody really thought it was necessary, since tracking airplanes through other means worked fine right up until it didn't.

Battery life ... I think the 30 days figure is the minimum spec, but in reality it can go on longer, depending on age of battery, i.e. when it was last replaced.

cnvogel 12y ago

This video has a teardown of an old flight data recorder (tape based), with a ultrasound pinger/locator beacon(at about 3 minutes into the video). http://youtu.be/mQehX0rVYuY?t=3m48s http://youtu.be/mQehX0rVYuY?t=3m48s Here's some technical information about this particular beacon. http://www.sea-avionics.com/lc/cart.php?target=productDetails&model=DK-100&substring=DK-100 http://www.sea-avionics.com/lc/cart.php?target=productDetail... It says that the shelf-life of the battery is only 6 years (which probably means that it will lose some significant part of its total capacity over 6 years). Having a device operate for "decades" surely will need different power sources. (even if cutting down on average power consumption drasticly, by only emitting one ping per week or so...)

leoc 12y ago
Sure, but exponential slowdown over maybe six months seems achievable, and would likely have been very useful in the case of MH370.
- mikeash 12y ago
  I think it just comes down to this being an extremely conservative field, and these systems get implemented based on past experience. Before MH370, basically nobody anticipated having to search for a commercial airliner with no idea where it went besides that it was vaguely somewhere within a continent-sized patch of ocean. The 30-day period was considered to be enough. Even with MH370 it could have been enough if the Malaysian authorities hadn't been so unbelievably incompetent as to waste an entire week searching the wrong ocean when they had data which definitively showed it went elsewhere. It's similar to the question of why airliners don't periodically report their position using GPS and satellite data, since they basically have the capability already. The answer is that nobody really thought it was necessary, since tracking airplanes through other means worked fine right up until it didn't.