Another proposed explanation is that Valentich became disoriented and was flying upside down. If this were the case, the lights he thought he saw would be his own aircraft's lights, reflected in the water; he would then have crashed into the water. However, the model Cessna he was piloting could not have flown inverted for long as it has a gravity feed fuel system, meaning that its engine would have cut out very quickly. Yet another proposed possibility is suicide. However, interviews with doctors and colleagues who knew him virtually eliminated this possibility.