"The float plane carrying former Sen. Ted Stevens that crashed in Alaska this week was equipped with a technology meant to alert the pilot that dangerous terrain was ahead, the National Transportation Safety Board's chairwoman said Friday. But it's not clear if the system was working just before the plane hit a steep, rugged mountainside, killing Stevens — the longest-serving Republican senator in U.S. history — and four others, chairwoman Deborah Hersman said at a news conference in Anchorage. The five victims died from blunt-force trauma, state medical examiner Dr. Katherine Raven said. Four people survived, and investigators interviewed two of them on Friday. Hersman said one of the survivors described Monday afternoon's crash by saying: ""They were flying along, and they just stopped flying."" The same survivor said he didn't notice any changes in the plane's pitch or hear any unusual engine sounds right before the plane went down about 20 miles north of Dillingham in southwest Alaska. Hersman didn't identify the survivors who spoke with officials on Friday. She did not say why she wasn't naming the two who were interviewed."