The Austrian-registered Cessna 551 aircraft was flying from Jerez in southern Spain, from where it took off at 1256 GMT without a set destination, according to FlightRadar24 website.
It turned twice, at Paris and Cologne, before heading straight out over the Baltic, passing near the Swedish island of Gotland. At 1737 GMT it was listed on the flight tracker as rapidly losing speed and altitude.
“We’ve learned that the plane has crashed [in the ocean] northwest of the town of Ventspils in Latvia,” a spokesperson for Sweden’s rescue service said. “It has disappeared from the radar.”
German and Danish war planes had earlier been sent to inspect the aircraft as it passed through those countries’ airspace, but were unable to make contact, said Johan Wahlstrom of the Swedish Maritime Administration.
“They could not see anyone in the cockpit,” he said.
German newspaper Bild reported that the plane was carrying the pilot, a man, a woman and a person it described as a daughter, without sourcing the information.
A Lithuanian air force helicopter was dispatched to the crash site for search and rescue at neighbouring Latvia’s request, a Lithuanian air force spokesperson said. Latvia said it had sent ships to the scene.
“Our ships are on the way to the position where the plane crash happened,” said Liva Veita, spokesperson of the Latvian navy.
A Stena Line ferry travelling from Ventspils to Norvik in Sweden was also redirected to the crash site, according to the MarineTraffic website. The website showed a Swedish search and rescue helicopter and airplane at the site as well.
The Lithuanian air force spokesperson said earlier that fighter aircraft from the Nato Baltic Air Police mission in Amari airfield in Estonia had taken off to follow the plane, without giving any more details.
The company listed as the aircraft’s owner in Austria’s aircraft register, Cologne-registered GG Rent, could not immediately be reached for comment.
(Reporting by Andrius Sytas, Terje Solsvik, Tomas Escritt; Writing by Philippa Fletcher; Editing by Frances Kerry and Hugh Lawson.)