(CNN) -- Searchers looking for the airplane that slammed into the side of a tree-covered Alaskan mountainside earlier this month couldn't detect an emergency locator signal after the impact damaged the craft's transmitter, according to a federal report released on Wednesday.
The National Transportation Safety Board issued a preliminary report about the August 9 accident that killed five people, including former Sen.Ted Stevens, R-Alaska, and injured four others.
"No emergency locator transmitter (ELT) signal was detected during the aerial search," the report said, "Examination of the wreckage revealed that the ELT had separated from its mounting bracket during impact, and the antenna cable was found separated from the ELT."
Weather conditions at the time of the accident were "not known," the report said, but Alaska Air National Guard rescuers were hampered by poor weather and terrain -- slogging for hours through rain, fog and wind to reach the rugged mountainside in southwestern Alaska.
The closest weather reporting station, at Dillingham Airport, about 18 miles south of the accident site, reported light rain and mist in cloudy and overcast conditions, with winds gusting to more than 26 mph just 10 minutes after the accident took place.
"At the time of the accident, marginal visual meteorological conditions were reported at the Dillingham Airport," the report said.
The four survivors included Willy Phillips Jr., 13. His father, former Stevens staffer Bill Phillips Sr., was among the five people killed in the crash.
The other survivors were former NASA administrator Sean O'Keefe and his 19-year-old son, Kevin, and Jim Moorhard of Alexandria, Virginia.
Along with Stevens, 86, and Bill Phillips, the others who died were pilot Terry Smith, 62, of Eagle River, Alaska; Dana Tindall, 48, of Anchorage, Alaska; and Corey Tindall, 16, of Anchorage, Alaska.
Autopsies on the five victims found the deaths were the result of blunt force trauma, injuries consistent with this type of crash, state officials said.
The report said the de Havilland DHC-3T Otter -- a single-engine, turbine-powered, amphibious float-equipped craft -- "sustained substantial damage" when it crashed about 10 miles northeast of Aleknagik about 2:45 p.m. Alaska Daylight Time.
it said the airplane was registered to and operated by General Communication Corporation in Anchorage and the flight "originated from a GCI-owned remote fishing lodge on the southwest shoreline of Lake Nerka" about 2:30 p.m.
It was headed to a "remote sport fishing camp on the banks of the Nushagak River, located about 52 miles southeast of the lodge." No flight plan had been filed.
A GCI representative said the pilot telephoned people at the camp to say the plane would arrive there, but a couple of hours later the plane had not arrived.
"The GCI lodge manager then initiated a phone and radio search to see if the airplane had diverted to Dillingham, Alaska or if it was en route back to the GCI lodge. Unable to locate the airplane, GCI lodge personnel initiated an aerial search along the pilot's anticipated route," the report said. Volunteers flying planes and helicopters joined in the search.
About 8:05 p.m., air searchers spotted the wreckage "along the anticipated flight route, about 900 feet above mean sea level in the Muklung Hills, in steep, heavily wooded terrain, about 19 miles southeast of the GCI lodge."
Searchers reached the accident site by helicopter and "confirmed that the pilot and four passengers died at the scene, and four passengers sustained serious injuries."
More rescue crew members were prevented from reaching the site at the time by "poor weather and dark night conditions" But the next morning, Coast Guard and Air National Guard helicopters evacuated everyone from the site.