As I noted above, a nuclear submarine can move fairly quickly (15+ kts) unhampered by high seas on the surface. And they are already equipped with a sonar suite of great power.(even one as old as the Tireless).

It's possible the US would be hesitant to use our subs in the area where the Chinese are searching for the wreckage using ASW planes. That could let the Chinese learn some things we don't want them to know if they get a track on one of our boats.

Arney,

Doppler shift still only gives speed toward or away from the satellite. It cannot give a vector because it cannot determine speed laterally (tangential direction). The later data appears to have come from additional analysis of the time delays from other aircraft taking similar paths in the same area.

Respectfully,

Jerry

The various satellites have different orbits and different altitudes. One constellation may do better with TDOA and others may be better with doppler. Different techniques are not mutually exclusive and actually tend to augment each other. The problem isn't the satellites or techniques (math is math) it is the sporadic nature of the target.

The fact that at this late date they haven't gotten the search area much smaller than it is tells me something stinks about the entire evolution, starting at Day One. There's a lot we're not being told, governments can be so secretive... But that's just my opinion.

Russ,

Unfortunately there was only one satellite. The INMARSAT system depends on a very few (11) satellites in geosynchronous orbit. The one in question is just north of the center of the Indian Ocean. My understanding is that the path of the aircraft never contacted another INMARSAT satellite, at least after it turned SW. It may have been in contact with the one located over New Guinea in the beginning, but even with more, since they are all in a straight line, still would not give anything but a set of arcs.

Respectfully,

Jerry

Thanks for the clarification, Jerry.

Finally a sub, shudda done that 2 weeks ago, maybe they did?
Still the pinger's are near end of life, why?
Sure batteries only last for a limited time, 30-45 days we are told. Again, why?
I can understand the expense aspect along with testing but I wonder why the first thought is just about the batteries.
Regardless of what batteries are used in any generation of device why
not install a timer circuit as a quick, perhaps easier to test and prove alternative?
IE Set a timer to offer different ping rates as battery life declines.
7 day's normal rate, 8-20 days 50% rate, 20-40 days 25% rate,
40- end of life 10% just to put a number there.
How long could the current gen. of batteries operate using this ping regime?
Perhaps that is how the current boxes are wired, I don't know but if not
why not? Would this be an easier fix to accomplish than trying to rebuild
the device with newer better and perhaps physically larger batteries?

I am not techologically literature in this field, but here is my idea. I would add a backup battery to start working when the first one dies. The 2nd system should remain in a hybernation mode until some radar/sonar ping is received from a search vessel nearby activates this battery to give pings for only half an hour and then "sleeps" again. I think such device would last much longer.

I was told the engine reporting system, the one that gave the satellite pings which told the searchers that the plane flew for hours after it was lost, was quite capable of reporting the planes speed and location as well as engine condition.
I was also told the cost of this service was only $10 a flight which the airline had declined as a cost saving measure.
($10 a flight, not $10 a ticket)

Maybe somebody more informed about avionics could explain this part of the story a bit better.

I considered a semi-passive system, ie listen for a signal and turn on but was concerned that whatever was done should have a chance of fitting into
the current recorder housing. Any major design changes will require extensive " destructive/survivability testing ". The current housing works, so do the batteries the question is how to make them last longer without external design change.

Why not require the recorders to fit in the skin of the aircraft and separate on impact? IIRC, I saw a comment on one of the news channels that this was the way some military aircraft were already set up. If so, the basic system is already designed, they just need to design the mounting to the aircraft.

P.S. If they separate, make them float & trigger a 406Mhz beacon.