Islamic State militants claim they downed a Russian jet killing all 224 people on board.
The wreckage was found in an area where Egyptian forces are fighting I.S. insurgents.
The Metrojet service was en route from Sharm el-Sheikh to in Russia when it came down over the Sinai desert.
However security sources in Egypt think a technical fault is probably to blame – with reports the pilot wanted to make an emergency landing before losing contact.
Sherif Ismail, the Egyptian prime minister, says they’ve already recovered the black box.