On August 21, 2010, 28-year-old Neal Joseph Spradlin boarded a de Havilland DHC-2 Beaver floatplane at Swikshak Bay in Katmai National Park, Alaska, with his 20-year-old brother Seth, a 26-year-old colleague Mason McLeod, and pilot 47-year-old Marco Alletto. The aircraft departed around 1:45 p.m. en route to Brooks Camp and King Salmon but never arrived, and no radio or emergency locator transmissions were received.

A massive search followed, with the U.S. Coast Guard, Alaska Air National Guard, National Park Service, Alaska State Troopers and others flying over the vast park. Teams covered more than 60,000 miles across mountainous terrain, river valleys and coastline, but found no trace until September 28, 2010, when fragmented wreckage including a tail piece with identifying numbers was seen on a beach about 10 miles northwest of Sukoi Bay. The damage suggested a high-impact collision with the ocean and there was no indication of survivors.

The National Transportation Safety Board investigated but, because recovered wreckage was limited and fragmented, could not determine a definitive cause. Does anyone have information about the flight, the maintenance crew’s work schedule, or observations from that August day that could shed light on what happened?