That's right Irv, there were 3 planes of the same type. I wondered if they were briefed to look for signs of airplane/wreckage on any of the islands they were tasked to overfly so, concentrated on the land, not the reef. They might have mistakenly assumed that the Gardner reef was always submerged in water, as it was when they overflew it? and, were unaware that at low tide it was comparitively dryish and inviting for a plane low on gas to put down so, didn't consider the possibility that there could be a plane mixed in with the surf? Just a possibility IMHO