Holidaymaker Maria Ivleva would have been killed instantly by the huge explosion just centimetres beneath her.
Reports in Russia say the device - which killed 224 people on October 31 - was likely to have been planted under seat 31A, where Miss Ivleva was sitting.
The teenager from St Petersburg had been on holiday in Sharm El Sheikh with her 44-year-old mother Marina, who was sitting in seat 31B.
There is no suggestion that any of the Russian tourists were suicide bombers.