Jet like object with an outer disc traveling south east at approx. 11,000 meters and flew under my plane whilst traveling from prauge to the uk. our heading and altitude was 297w at 11,511 meters and the object was heading 112â°se at approx. 11, 000 when it came from under our plane at a slower than average plane speed (around 200mph). the object was grey/lead in colour with a black disc and looked like someone had attached an outer disc to a military jet as the wings were fixed at 45â° backwards. i was unable to get a picture but i went over the flight logs and got the exact time, direction, altitude and location that i first saw the object. due to our heading and the direction the object was flying, it was out of sight within no more than 20 seconds as it was skimming the clouds in the upper atmosphere (probably as cover). i have been to numerous raf bases in the uk and know my shit about everything military aircraft related and have never been a believer in ufo's until today!!