COPENHAGEN, Denmark -- Investigators sifted through wreckage and personal effects Saturday in hopes of determining what caused a Norwegian charter plane to crash into the sea Friday, killing all 55 aboard.
Search vessels trawling off the Danish coast found only small bits of wreckage in their search for the flight recorder of the 36-year-old, American-built Convair CV-580 Metropolitan turboprop owned by the Norwegian Partnair company.
The aircraft was flying from Norway to West Germany with 50 employees of Norway's Wilhelmsen shipping line when it fell from an altitude of 22,000 feet.
The employees had won a company lottery for the 50 seats in the aircraft that was taking them to a christening ceremony in Hamburg for Wilhelmsen's new ship, Topaz.
In Norway, flags flew at half-staff Saturday at all public buildings and there were emotional scenes at Wilhelmsen Line's Oslo offices where relatives sought aid.
Norwegian Prime Minister Gro Harlem Brundtland, who flew in the twin-engine plane two weeks ago during an election tour of Norway, announced party leaders had canceled all further campaigning for Monday's general election.
'This is a major tragedy. The only decent thing to do is to stop campaigning,' said Brundtland.
By Saturday morning, the bodies of 10 women and 21 men had been recovered and 24 others, including five crew members, were presumed dead in the worst air tragedy ever to hit Scandinavia. Three of those killed carried British passports and the remaining 52 were Norwegians.
'We found 31 bodies on Friday evening but have not found any of the others,' Danish Air Force spokesman Hugo Stigsen told United Press International.
He said Danish and Norwegian flight investigators were in the small Danish fishing port of Hirtshals, on the Kattegat waterway some 20 miles from the scene of the crash, sifting through wreckage and personal effects ferried in by a chain of trawlers helping search for debris and bodies.
Stigsen said 15 ships and three helicopters were taking part in the search off northern Denmark and attempts were made to trawl the seabed for wreckage in water 60 to 270 feet deep.
'We have found a lot of small bits of wreckage and it is all being pieced together,' Stigsen said. 'We desperately want to find the flight recorder in order to find out what happened.'
Rescue personnel said search conditions were becoming difficult because of choppy seas and reduced visibility.
Search vessels initially criss-crossed the area using sonar to try to locate wreckage on the sea bed. That effort tapered off Saturday as searchers began concentrating on finding items on the surface.
Rescuers said further exploration of the sea-bed would be delayed until a specially equipped Norwegian vessel arrived Sunday to search for larger wreckage and the flight recorder.
West German ships conducting NATO exercises in the area initially led the search effort but returned Saturday morning to Kiel and turned the search over to the Danish coast guard.
Airport authorities declined further comment as to the cause of the crash. Friday, a spokesman for Oslo's international airport said a heavy explosion seemed the most likely cause.
'The plane was flying at 22,000 feet and suddenly disappeared from radar screens. It seems only a major explosion could have caused that,' said the spokesman.
But Danish flight investigators in Hirtshals said metal fatigue could have been a factor, causing a major part of the aircraft to detach in mid-flight.
Norway's main national daily Aftenposten reported Saturday the plane was involved in a serious incident July 3, 1978, while it was owned by SAHSA, an airline in Honduras.
The newspaper quoted data from the Airline Production List, produced by a U.S. organization, Aviation Data Center, but gave no details of the incident.
According to Partnair, the operators of the aircraft, the plane was given a full inspection in Canada a week ago.
