The search area for Malaysia Airlines flight MH370 needs to be significantly reduced for the black box pinger detector to do its job, said a United States navy officer in charge of the sophisticated equipment.
Captain Mark Matthews said it was critical to find the surface debris so that the area, where the underwater search would be conducted, could be reduced.
"Right now the search area is basically the size of the Indian Ocean, which would take an untenable amount of time to search," he was quoted by The Telegraph.
Another US navy official, Commander William Marks, told CBS News: "You have to wonder if the debris is even out there."
Dr Todd Curtis, an aviation expert and former Boeing engineer, told The Telegraph that the hunt for the plane could turn into a "Titanic"-style quest that could last for years.
He said the black box was unlikely to be found before its 30-day pinger – which helps searchers locate both the box and the plane – runs out of battery life in about a week.
"The likelihood of finding the plane quickly, especially given the pinger will soon end, is going down astronomically," he told the daily.
"Even if they found the debris today, there is the problem of estimating where it drifted over the past three weeks and then estimating the new area. It all has the potential to take much more than two years."
Curtis warned that the search was likely to be "very prolonged" and may end in failure, at least in the short term.
"There is a chance they will never find the plane," he said. "If it is not found, it will turn into a Titanic-type search – something that won't be forgotten by either the general public or the countries involved."
The search for MH370, which disappeared on March 8 with 239 people on board, has entered the fourth week with no concrete clues to the location of the missing aircraft.
Several satellite sightings of possible objects, as well as a number of objects retrieved from the ocean, turned out to be not related to the missing plane.
The Australian Maritime Safety Authority had said in a statement that the objects had been examined on the ships and were described as fishing equipment and other flotsam.
An Australian military aircraft has also spotted four orange objects at sea, once again raising hopes that they might be linked to flight MH370.
"We were able to rule a few out as fishing buoys and fishing nets, however, of interest today we did encounter an area within approximately five nautical miles which included at least four orange coloured objects greater than approximately two metres in size each," said Flight Lieutenant Russell Adams, who leads the Australian P-3 Orion crew.
Senior US lawmakers said yesterday that investigators found no evidence of terrorism in the disappearance of the plane.
"I have seen nothing yet that comes out of the investigation that would lead me to conclude that (this was) ... anything other than a normal flight that something happened and something went wrong," House Intelligence Committee Chairman Mike Rogers told "Fox News Sunday".
The lack of concrete leads had been hard for the families of passengers and crew, with many saying they need proof that the flight had indeed ended in the Indian Ocean as announced by Prime Minister Datuk Seri Najib Razak last Monday.
Some of the families, especially those from China, had accused Malaysian authorities of withholding information. – March 31, 2014.