The search co-ordinator insisted the latest developments should be treated as unverified "until such time as we can provide an unequivocal determination"."We are working in a very big ocean and within a very large search area, and so far since the aircraft went missing we have had very few leads which allow us to narrow the search area," he said.
I have checked it in Longman and I have my doubts whether its meaning has to do with second or third definition. Here is the link to Longman. Could you simplify it? http://www.ldoceonline.com/dictionary/determination