AUSTRALIAN pilot Russell Adams, who was captaining the Australian AP-3C Orion plane, told reporters at Pearce air base on Saturday afternoon that while the weather was good and visibility about 4km or more, "the crew had a bit of difficulty discerning the differences between objects and white caps".

White cap is a wave with a crest of foam.

He and his colleagues did not, however, manage to spot anything significant during their 10-hour flight.

Various aircraft have spotted objects potentially linked to MH370 in the search area in recent days though they have yet to be relocated and identified.

Flight Lieutenant Adams described the process by which his colleagues would try to mark an object for relocation once it was spotted.

"Everybody on board the aircraft would hear the 'mark mark mark' call," he said.

"Up the front from the flight station we will drop a smoke buoy, a flare which emits smoke for about 45 minutes. At the same time the tactical coordinator uses a button on the aircraft system that would drop a GPS point.

"We would then attempt to maintain visual contact with that object…and reposition the aircraft to get photographs of it."

These photographs would then be sent for analysis, he said.