What damages their credibility for you? Why would they be lying? The accounts corroborate each other and were all reported to the police station on the same day. There is absolutely zero evidence they made anything up. What evidence do you have of it being a helicopter? How is it possible that all the eyewitnesses mistook a helicopter for a silver sphere with lights underneath it? A helicopter makes quite a distinctive and unmistakeable noise. Why did they not recognize it as a helicopter? Was there a bush fire happening near there on that day?