WASHINGTON (AP) — The pilots of two Alaskan sightseeing planes that collided in midair couldn’t see the other aircraft because airplane structures or a passenger blocked their views. They also didn’t get electronic alerts about close aircraft because safety systems weren’t working properly. That’s what the staff of the National Transportation Safety board found in their investigation of the May 2019 crash, which killed six people. Ten others were injured when the aircraft converged at 3,350 feet (1,021 meters). The Ketchikan-based floatplanes carrying passengers from the same cruise ship, the Royal Princess, were returning from tours of Misty Fjords National Monument. The planes collided just after noon over the west side of George Inlet.