It is thought that one of the newly discovered "four large objects", found by an Indonesian navy ship's sonar, could be the vital tail section of the plane.
Bambang Soelistyo, search and rescue agency chief, told the BBC that the larger of the newly discovered objects was 10x5m (32ft by 16dt).
Salvage expert David Mearnes told the BBC: "They know there are two objects down there, but they do not know exactly which pieces they are.They have indicated that one could be the tail section. That would be incredibly important."
Mearnes commented how the tail section will have appeared as a distinctive "acoustic shape and shadow on the sunbed" when it appears on the ship's sonar.
"The cross made by the horizon and vertical stabilisers gives a very special acoustic shape and shadow on the seabed, using their instruments. That is why they might know they have got the tail section."
"Importantly, two black boxes are located in the tail section. So if they have already found that tail section, the black boxes shouldn't be that far away."
When asked why the search operators have struggled to find the black boxes, Mearns said that the black boxes' tracking system was "not infalliable" and that "it works most of the time but not all of the time".
"There could be a number of reasons. First, the system is not infallible, so certain times the pingers don't initiate.
"Also the pingers are physically attached to the black box by two brackets. Sometimes those brackets break during the crash and the pinger and the black box get separated. The pinger could be in a completely different location far away.
"This is going to take a while. They are progressing quite quickly when you consider they lost a couple of days to weather."