Seachers for lost Malaysia Airlines flight MH370 have always been concerned that wreckage might have come to rest in complex canyons or slopes or ‘holes’ in the south Indian Ocean sea floor search zones where it might escape detection by towed deep water sonar scanning devices.
Those concerns, and the blanks left unprobed during the current systematic sweeps of the sea bed, are to be addressed by a large autonomous underwater vehicle or AUV deployed from an additional search vessel, the Fugro Supporter, from later this month.
Fugro Supporter will join the other contracted ships, the Fugro Equator and Fugro Discovery and the GO Phoenix, which have been involved in the search effort to date.
It means that by May, when the primary ocean search should have been completed, any doubts that a piece of wreckage has been missed ought to have been removed.
It would make a decision to abandon the Australian managed search possibly easier to justify to the aggrieved relatives of the victims of the MH370 disappearance, although no one at an official level has done anything more than hint that May might be when the curtain is drawn over this baffling mystery.
The search areas, as shown in the map below, lie along the so called seventh arc of possible locations from which an Inmarsat satellite parked in equatorial geosynchronous orbit over the Indian Ocean near the east coast of Africa heard the last pings coming from a computer server on board the 777, which was carrying 239 people on a flight from Kuala Lumpur to Beijing when it suddenly disappeared over the Gulf of Thailand on 8 March last year.
It is possible that MH370 struck the ocean with such force that it was torn into small fragments that may in turn be buried under silt or hidden in crevices on the sea floor, which in places is as deep as about 6000 metres, and in others, as relatively shallow as 600 metres.
However the two engines and some of the heavier sections of the jet, such as the wheel structures and any metallic cargo containers or other underfloor objects are expected to have sunk comparatively intact making them easier to detect. The frames of seat racks may have settled in sufficient concentrations to create an anomalous return on the various scanners being used to examine the selected strips of sea floor.
The Kongsberg HUGIN 4500 AUV about to go down on the black holes will be the second such device deployed in the search for MH370. Last year the US Navy loaned a sophisticated but smaller AUV, a Bluefin-21, for use in the early unsystematic period of the sea floor search, in which it investigated areas where pings from MH370’s two black boxes had mistakenly been thought to have been heard.
The JACC describes its role as follows:
The AUV will be used to scan those portions of the search area that cannot be searched effectively by the equipment on the other search vessels. It is not connected to the ship by cable, but is rather deployed with a pre-programmed area of the sea floor to investigate. After each underwater mission, the AUV will ascend automatically and return to the Fugro Supporter in order for the gathered data to be downloaded and the AUV’s batteries to be changed out with a spare charged set.
This larger device, made by Norwegian firm Kongsberg Marine, is not only more capable in its instrumentation and performance specifications, but has the advantage of targeting areas identified by a detailed bathymetic survey of what is otherwise unknown or little mapped parts of the ocean floor.
These surveys have allowed the towed sonar scanning devices currently doing the systematic search to avoid hazardous obstacles like unmapped sea mounts that might otherwise destroy them. This work is critical to the success of the Kongsberg device in being able to enter and search the most difficult to see parts of the ocean floor terrain.
Whether use of this device finds MH370, or helps consign it to the forgetfulness of the future, is yet to be determined.