It's rumoured that the ATSB and Fugro people are concerned that there are "shadows" and "holes" in the sonar results produced by the Fugro ships from the current search area, that are possibly hiding the wreckage of MH370.
These shadows and holes are produced by areas of the seabed in the search area that contain major deep depressions, ravines and canyons. Nowhere is this problem more obvious, than in the Northern arc of the search zone, where it approaches Broken Ridge - an underwater feature that contains the Diamantina Trench.
The Diamantina Trench is a canyon that contains the deepest section of the Indian Ocean currently known, the Diamantina Deep (at 35°S and 104°E) - measured by the Australian ocean research ship of the same name in 1961, at 8047 metres.
No-one knows exactly how deep the Diamantina Trench is in the region of the search arc. The entire current search zone falls within the Northern Kerguelen Plateau to the Broken Ridge formation, which fortunately for the searchers, is mostly flattish or mildly sloping terrain ranging from 800 to 3000 metres.
The Diamantina Trench is not a vertical-sided trench, it is a canyon with steeply-sloping walls - imagine one with slopes it would be difficult to drive a car up.
There is a need for the searchers to now try and examine the shadows and holes found in the current search, and to try and get a picture of what may lie in the Diamantina trench, and any other minor trenches in the extended search zone.
Accordingly, the rumour is that a Kongsberg HUGIN AUV has been acquired just prior to the Australian Winter and it has been sitting in Fremantle awaiting the smoother Indian Ocean wave and swell states of Spring and Summer, to deploy it.
The Winter wave and swell conditions of the Southern Indian Ocean are apparently conditions that are too risky to operate in, with the HUGIN AUV.
It is no doubt, an expensive piece of kit. It is apparently fitted with Kongsbergs proprietary SAS (Synthetic Aperture Sonar) system, which produces stunningly clear images of seabed objects utilising multiple sonar beams aimed at slightly different angles, along with powerful computing processors, to produce an excellent final image.
The HUGIN AUV with SAS has the ability to cover up to 200M each side of the AUV, at a tow rate of up to 6 Knots.
The HUGIN AUV until recently, only had a depth capacity of 3000 metres. However, an improved model now has a capacity of 4500 metres, and this is the model currently on hand in Fremantle.
It's rumoured that the ATSB and Fugro hope the HUGIN AUV fitted with the SAS sensor system will be the right product that will unlock the secrets of the deep Indian Ocean, and with some luck and more time and effort, it may be the device that finally reveals the resting place of any wreckage from MH370.
HUGIN AUV Brochure and Specification
KONGSBERG HISAS 1030 Brochure