The US passenger plane that crashed in Buffalo, New York, two days ago killing all 49 people onboard and another on the ground "was on autopilot", an aviation official has said.
Steve Chealander, a National Transportation Safety Board (NTSB) member, told the AP news agency on Sunday that preliminary investigations indicated the autopilot was still on when the plane crashed.
However, investigators are waiting to examine information from the plane's flight data recorder, also known as a black box, before confirming whether the autopilot was still engaged at the time of the crash.
Chealander said that the NTSB recommends pilots fly manually in icy conditions.
"You [the pilot] may be able to sense something sooner than the autopilot can sense it," Chealander said.
"You may be able to sense something sooner than the autopilot can"
Steve Chealander, US aviation official, on why pilots are advised to fly manually in icy weather
US federal investigators recovered the black box recorders from the smouldering wreckage on Friday.
The Colgan Air Bombardier Dash Q400 had crashed into a residential area en route to a local airport in the city of Buffalo earlier during the day.
Air traffic control radio messages reportedly indicated that although conditions were hampered by fog and some wind, there were no indications of problems and no "mayday call".
The aircraft is believed to have been approaching Buffalo Niagara International airport amid snow and fog when it came down on a suburban street at around 10:10pm (0310 GMT).
A county official said "the plane simply dropped off the radar screen".
Alison Des Forges, a prominent writer and human rights expert on Rwanda, was among those killed, David Patterson, the New York governor, said.
Barack Obama, the US president, said he offered his "thoughts and prayers" to those affected by the "terrible tragedy".
Witnesses described their horror as the jet descended over the neighbourhood before crashing into a house, killing one of the inhabitants.
"We heard a very low humming sound, like a buzz. It was something I have never heard before. Then there was dead silence," a local resident told Fox News.
"After that dead silence, the whole building shook. At that point, you heard a terrifying boom, like a crash."
"It was terrifying. [And] when you got to the scene, [the fire] was so intense that there was no hope. You knew that there were not going to be any survivors."
The plane was the first fatal commercial airline crash in the United States since August 27, 2006, when 49 people were killed after a Comair jetliner mistakenly attempted to take off from a Kentucky runway that was too short.