Originally Posted by SLFplatine
-After 10 days of SAR no wreckage has been found
-Thus the second possibility is most likely
Let me offer the view of someone with experience of North Atlantic open sea SAR (10 years).
It doesn't surprise me that they haven't found anything yet, because the search area is enormous, and the further away in time we go, the higher the uncertainty. Also, finding stuff in the sea is very difficult, even with Radar, IR, etc. It depends on weather, sea state, what sensor you are using, what you are looking for, etc. Remember than in the AF case there was a relatively good fix on their estimated position, here we are talking about searching (almost) a whole ocean. If the a/c flew for 7 hours, we don't have any idea of where it went, the uncertainty is huge, it's a nightmare from a SAR point of view.
Also, you have to understand something called "Coverage Factor".
When you do SAR, be it with airplanes, helis, or even ships, each Search Unit has a "view range" (it can be visual, radar, IR, whatever), over which it won't be able to detect anything - the technical name is "sweep width".
Now, when you have a small search area, you get the SAR vehicle to cover it with a given pattern (there are several types), in such a way that its track guarantees that the whole area is covered by the area "drawn" by the sweep width as you move along:
http://navyflightmanuals.tpub.com/P-553/P-5530149im.jpg
That's the figure to the right, which has a coverage factor of 1.0.
In the previous picture, notice the pattern on the left, because in that one, the coverage factor isn't 1.0, it's probably 0.5 or something like that.
When you cover huge areas (such as this case of MH370), if you aim for a CF of 1.0 you need lots and lots (and lots and lots!!!) of search units, which costs lots and lots of $$$, so what is usually done is simply to use math and get CF of between 0.5 and 1.0, according to several factors. You actually don't cover the whole area, you go through it with "gaps" to make sure you pass over it as quickly as possible, because as time goes by, the search area increases (due to uncertainty caused by the wind, sea currents, etc). So I'm sure they aren't using CF of 1.0 to cover the whole Indian Ocean, I think maybe not even 0.5...
If you realize that they are now searching in an ocean area that goes from India almost to Antactica, it's no surprise that they haven't found the a/c yet, assuming that it crashed into the ocean after 7 hours of flight, and it's also the reason why the conspiracy theories are growing.
Call me a pessimist, but as time goes by, the odds of finding debris go down, and with a search area this big, I find it possible (not very likely, but possible) that they'll never find anything... That is assuming, as I do, that the a/c had an emergency that incapacitated the pilots and the plane flew for hours until it ran out of fuel (I don't buy the media hype, sorry, if you have a strong electrical fire and you start to shutdown systems, your priority is not talking to ATC).
Either way, this is only me speculating on the limited information we have so far, and most of it filtered by the media.