The business publication Forbes.ru has estimated Fileva's fortune at $600 million. Russian news reports said Fileva, who co-owned S7 with her husband, was traveling with her father. German police have said there were two Russian citizens on board but haven't provided any positive identification of the victims yet.
The plane took off from the Mediterranean city of Cannes, a popular holiday destination for rich Russians on the glitzy French Riviera. The cause of the crash remained unclear on Monday. Knut Happel, a spokesman for prosecutors in Darmstadt, said investigators hope for evidence from witnesses and the burnt-out wreckage itself but, given the state of the plane, it will probably take "some time" to establish.
The Moscow-based Interstate Aviation Committee, which investigates crashes involving planes from Russia and other ex-Soviet nations, said in a statement that it sent a group of experts to help the German investigation.
With a base at Moscow's Domodedovo Airport, S7 is part of the Oneworld alliance and flies to 150 destinations in 35 countries, using 56 Airbus planes and 23 aircraft from Boeing. Fileva's husband, Vladislav Filev, is chair of the company's board of directors, according to the company's third-quarter 2018 financial statement.
Epic Aircraft, a Bend, Oregon-based company that developed the Epic LT, didn't immediately respond to a request for comment.