* Witnesses describe pulling people from wreckage
* Investigators point to pilot error
* Authorities say no passengers were aboard, only crew
By Alissa de Carbonnel
MOSCOW, Dec 29 (Reuters) - A Russian airliner flying without passengers broke into pieces after it slid off the runway and crashed onto a highway outside Moscow upon landing on Saturday, killing four of the eight crew on board and leaving smoking chunks of fuselage on the icy road.
The crash during peak holiday travel ahead of Russia's New Year's vacation, which runs from Sunday through Jan. 9, cast a spotlight on the country's poor air-safety record despite President Vladimir Putin's calls to improve controls.
Television footage showed the Tupolev Tu-204 jet with smoke billowing from the tail end and the cockpit broken clean off the front.
Some witnesses told state channel Rossiya-24 they saw a man thrown from the plane as it rammed into the barrier of the highway outside Vnukovo airport, just southwest of the capital, and another described pulling other people from the wreckage.
"The plane split into three pieces," Yelena Krylova, chief spokeswoman for the airport, said in televised comments.
Police spokesman Gennady Bogachyov said: "The plane went off the runway, broke through the barrier and caught fire."
The pilot, co-pilot, flight engineer and a flight attendant were killed and the other four crew members aboard - all flight attendants - were in a serious condition in hospital with head injuries, the Emergency Situations Ministry said.
Officials said earlier that there were 12 crew on board.
The mid-range Tu-204 was operated by Russian airline Red Wings and was travelling from the Czech Republic, Krylova said.
Wreckage from the crash was scattered across the highway and the plane's wings were torn from the fuselage, witnesses said.
"We saw how the plane skidded off the runway ... The nose, where business class is, broke off and a man fell out," a witness, who gave his name as Alexei, said. "We helped him get into a mini-bus to take him to the hospital."
Another witness described pulling four people from the wreckage when he arrived at the scene before emergency service workers. "We could not get the pilot out of the cockpit but we saw a lot of blood," he told Rossiya-24.
Russian investigators said preliminary findings pointed to pilot error as the cause of the crash.
Russia's aviation authority said it had sent state-owned Tupolev a warning ordering it to fix problems that may have caused a Tu-204 with 70 aboard to go off a Siberian runway on Dec. 21 after suffering engine and brake trouble on landing. It said similar problems had occurred before.
The billionaire owner of Red Wings, Alexander Lebedev, said the airline had already carried out the order on its Tu-204s. Red Wings' website said it operated nine of the aircraft.
Lebedev said the Tu-204 in Saturday's crash was built in 2008 and that the pilot was experienced, with 14,500 hours of flying time. He offered condolences to the victims' families and promised financial compensation and other help.
Russia and other former Soviet republics had some of the world's worst air-traffic safety records last year, with a total accident rate almost three times the world average, the International Air Transport Association said.
A passenger jet crashed and burst into flames after takeoff in Siberia in April, killing 31 people, and an airliner slammed into a riverbank in September 2011, wiping out the Lokomotiv Yaroslavl ice hockey team in a crash that killed 44 people.
The Russian-built Tu-204, which is comparable in size to a Boeing 757 or Airbus A321, is a Soviet-era design that was produced in the mid-1990s but is no longer being made. There have been no major accidents reported involving Tu-204s.