He said the task was “very complex”, “very demanding” because the teams had no hard information to work from.
Houston said no time frame had been set for the search to end, but that a new approach would be needed if nothing showed up.
“Over time, if we don't find anything on the surface, we're going to have to think about what we do next, because clearly it's vitally important for the families, it's vitally important for the governments involved that we find this airplane,” he told ABC news.
Yesterday, Malaysian authorities released the full transcript of the communications between flight MH370 and air traffic control, revising its earlier account of the final words from the cockpit.
The transcript shows the last voice transmission from the doomed Boeing 777-200 plane was “Good night Malaysian three-seven-zero,” not the “All right, good night” transmission authorities had previously used.
