Pilot Error or Mechanical Failure Most Likely Caused Plane Crash in Russia, Investigators Say

All 62 people on board were killed in the crash.

— -- Investigators are looking at pilot error or mechanical failure as possible causes of a FlyDubai flight's deadly crash in Russia, a representative from Russia's Investigative Committee said in a briefing today.

Investigators suggested earlier that bad weather could have been the primary cause, but now they say that if the crash wasn't caused by a mechanical failure, it may have been caused by the pilot not handling the weather conditions properly.

"Two theories of the plane crash are being explored... The first one is pilot error in acting in difficult meteorological conditions, and the second is mechanical failure," said Oksana Kovrizhnaya, a spokeswoman for the Investigative Committee's Southern Transport Investigative Department.

Kovrizhnaya also said that wind speed at the time of the crash was reaching 18 meters per second -- roughly 40 miles per hour, which could have caused the pilot error.

"Winds in and of themselves should not bring an airplane down. So perhaps it was a contributing factor," ABC News aviation consultant Col. Stephen Ganyard said.

"I think something else went wrong," Ganyard said. "Perhaps pilot disorientation. Perhaps this pilot was looking out the window trying to find the airport at night. And when you have night, and you've lost horizon, it's not hard to get visually disoriented and lose track of which way is up.

"I think we're going to find something that indicates that this was human error," he said.

Russian investigators have not said they are pursuing terrorism as a main theory.

Investigators are now looking at radio exchanges between the pilots and the air traffic controllers.

Boeing, which made the aircraft, and the Federal Aviation Administration are also participating, according to the NTSB.

A U.S. official briefed on the investigation told ABC News that the request for U.S. assistance is "unusual" but not unprecedented. It also reinforces that all signs point to the cause being accidental as opposed to terrorism or a criminal act.

All 62 people on board were killed when the flight crashed in Southern Russia, according to Russia's Emergencies Ministry,

The victims included 55 passengers and seven crew members.